1.
Alkali metal
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The alkali metals are a group in the periodic table consisting of the chemical elements lithium, sodium, potassium, rubidium, caesium, and francium. Indeed, the alkali metals provide the best example of trends in properties in the periodic table. The alkali metals are all shiny, soft, highly reactive metals at standard temperature and pressure and they can all be cut easily with a knife due to their softness, exposing a shiny surface that tarnishes rapidly in air due to oxidation by atmospheric moisture and oxygen. Because of their reactivity, they must be stored under oil to prevent reaction with air. Caesium, the alkali metal, is the most reactive of all the metals. All the alkali metals react with water, with the alkali metals reacting more vigorously than the lighter ones. Experiments have been conducted to attempt the synthesis of ununennium, which is likely to be the member of the group. Most alkali metals have different applications. One of the applications of the pure elements is the use of rubidium and caesium in atomic clocks, of which caesium atomic clocks are the most accurate. A common application of the compounds of sodium is the sodium-vapour lamp, table salt, or sodium chloride, has been used since antiquity. The physical and chemical properties of the alkali metals can be explained by their having an ns1 valence electron configuration. Hence, all the metals are soft and have low densities, melting and boiling points, as well as heats of sublimation, vaporisation. They all crystallise in the cubic crystal structure, and have distinctive flame colours because their outer s electron is very easily excited. The ns1 configuration also results in the alkali metals having very large atomic and ionic radii, most of the chemistry has been observed only for the first five members of the group. The chemistry of francium is not well established due to its radioactivity, thus. What little is known about francium shows that it is close in behaviour to caesium. The physical properties of francium are even sketchier because the element has never been observed. The alkali metals are more similar to other than the elements in any other group are to each other
2.
Lithium
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Lithium is a chemical element with the symbol Li and atomic number 3. It is a soft, silver-white metal belonging to the metal group of chemical elements. Under standard conditions, it is the lightest metal and the least dense solid element, like all alkali metals, lithium is highly reactive and flammable. For this reason, it is stored in mineral oil. When cut open, it exhibits a metallic luster, but contact with moist air corrodes the surface quickly to a silvery gray. Because of its reactivity, lithium never occurs freely in nature, and instead, appears only in compounds. Lithium occurs in a number of minerals, but due to its solubility as an ion, is present in ocean water and is commonly obtained from brines. On a commercial scale, lithium is isolated electrolytically from a mixture of lithium chloride, the nucleus of the lithium atom verges on instability, since the two stable lithium isotopes found in nature have among the lowest binding energies per nucleon of all stable nuclides. Because of its relative instability, lithium is less common in the solar system than 25 of the first 32 chemical elements even though the nuclei are very light in atomic weight. For related reasons, lithium has important links to nuclear physics, the transmutation of lithium atoms to helium in 1932 was the first fully man-made nuclear reaction, and lithium-6 deuteride serves as a fusion fuel in staged thermonuclear weapons. These uses consume more than three quarters of lithium production, Lithium is found in variable amounts in foods, primary food sources are grains and vegetables, in some areas, the drinking water also provides significant amounts of the element. Human dietary lithium intakes depend on location and the type of foods consumed, traces of lithium were detected in human organs and fetal tissues already in the late 19th century, leading to early suggestions as to possible specific functions in the organism. However, it took another century until evidence for the essentiality of lithium became available, in studies conducted from the 1970s to the 1990s, rats and goats maintained on low-lithium rations were shown to exhibit higher mortalities as well as reproductive and behavioral abnormalities. Lithium appears to play an important role during the early fetal development as evidenced by the high lithium contents of the embryo during the early gestational period. The available experimental evidence now appears to be sufficient to accept lithium as essential, the lithium ion Li+ administered as any of several lithium salts has proven to be useful as a mood-stabilizing drug in the treatment of bipolar disorder in humans. Like the other metals, lithium has a single valence electron that is easily given up to form a cation. Because of this, lithium is a conductor of heat and electricity as well as a highly reactive element. Lithiums low reactivity is due to the proximity of its electron to its nucleus
3.
Sodium
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Sodium is a chemical element with symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal, Sodium is an alkali metal, being in group 1 of the periodic table, because it has a single electron in its outer shell that it readily donates, creating a positively charged atom—the Na+ cation. Its only stable isotope is 23Na, the free metal does not occur in nature, but must be prepared from compounds. Sodium is the sixth most abundant element in the Earths crust, Sodium was first isolated by Humphry Davy in 1807 by the electrolysis of sodium hydroxide. Among many other useful compounds, sodium hydroxide is used in soap manufacture, and sodium chloride is a de-icing agent. Sodium is an element for all animals and some plants. Sodium ions are the major cation in the fluid and as such are the major contributor to the ECF osmotic pressure. Loss of water from the ECF compartment increases the sodium concentration, isotonic loss of water and sodium from the ECF compartment decreases the size of that compartment in a condition called ECF hypovolemia. In nerve cells, the charge across the cell membrane enables transmission of the nerve impulse—an action potential—when the charge is dissipated. The melting and boiling points of sodium are lower than those of lithium but higher than those of the alkali metals potassium, rubidium. All of these high-pressure allotropes are insulators and electrides.3 nm, spin-orbit interactions involving the electron in the 3p orbital split the D line into two, at 589.0 and 589.6 nm, hyperfine structures involving both orbitals cause many more lines. Twenty isotopes of sodium are known, but only 23Na is stable, 23Na is created in the carbon-burning process in stars by fusing two carbon atoms together, this requires temperatures above 600 megakelvins and a star of at least three solar masses. Two nuclear isomers have been discovered, the one being 24mNa with a half-life of around 20.2 milliseconds. Sodium atoms have 11 electrons, one more than the stable configuration of the noble gas neon. This process requires so little energy that sodium is oxidized by giving up its 11th electron. In contrast, the ionization energy is very high, because the 10th electron is closer to the nucleus than the 11th electron. As a result, sodium usually forms ionic compounds involving the Na+ cation, the most common oxidation state for sodium is +1. It is generally less reactive than potassium and more reactive than lithium, Sodium metal is highly reducing, with the reduction of sodium ions requiring −2.71 volts, though potassium and lithium have even more negative potentials
4.
Potassium
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Potassium is a chemical element with symbol K and atomic number 19. It was first isolated from potash, the ashes of plants, in the periodic table, potassium is one of the alkali metals. Potassium in nature only in ionic salts. It is found dissolved in sea water, and is part of many minerals, naturally occurring potassium is composed of three isotopes, of which 40K is radioactive. Traces of 40K are found in all potassium, and it is the most common radioisotope in the human body, Potassium is chemically very similar to sodium, the previous element in Group 1 of the periodic table. They have a similar energy, which allows for each atom to give up its sole outer electron. That they are different elements combine with the same anions to make similar salts was suspected in 1702. Most industrial applications of potassium exploit the high solubility in water of potassium compounds, heavy crop production rapidly depletes the soil of potassium, and this can be remedied with agricultural fertilizers containing potassium, accounting for 95% of global potassium chemical production. Potassium ions are necessary for the function of all living cells, fresh fruits and vegetables are good dietary sources of potassium. Potassium is the second least dense metal after lithium and it is a soft solid with a low melting point, and can be easily cut with a knife. Freshly cut potassium is silvery in appearance, but it begins to tarnish toward gray immediately on exposure to air, in a flame test, potassium and its compounds emit a lilac color with a peak emission wavelength of 766.5 nanometers. Neutral potassium atoms have 19 electrons, one more than the stable configuration of the noble gas argon. This process requires so little energy that potassium is readily oxidized by atmospheric oxygen, in contrast, the second ionization energy is very high, because removal of two electrons breaks the stable noble gas electronic configuration. Potassium therefore does not readily form compounds with the state of +2 or higher. Potassium is an active metal that reacts violently with oxygen in water. With oxygen it forms potassium peroxide, and with water potassium forms potassium hydroxide, the reaction of potassium with water is dangerous because of its violent exothermic character and the production of hydrogen gas. Hydrogen reacts again with atmospheric oxygen, producing water, which reacts with the remaining potassium and this reaction requires only traces of water, because of this, potassium and the liquid sodium-potassium — NaK — are potent desiccants that can be used to dry solvents prior to distillation. Because of the sensitivity of potassium to water and air, reactions with other elements are only in an inert atmosphere such as argon gas using air-free techniques
5.
Rubidium
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Rubidium is a chemical element with symbol Rb and atomic number 37. Rubidium is a soft, silvery-white metallic element of the metal group. Elemental rubidium is highly reactive, with similar to those of other alkali metals. German chemists Robert Bunsen and Gustav Kirchhoff discovered rubidium in 1861 by the developed technique. Rubidiums compounds have various chemical and electronic applications, rubidium metal is easily vaporized and has a convenient spectral absorption range, making it a frequent target for laser manipulation of atoms. Rubidium is not a nutrient for any living organisms. However, rubidium ions have the charge as potassium ions. Rubidium is a soft, ductile, silvery-white metal. It is the second most electropositive of the alkali metals. Similar to other metals, rubidium metal reacts violently with water. As with potassium and caesium, this reaction is vigorous enough to ignite the hydrogen gas it produces. Rubidium has also reported to ignite spontaneously in air. It forms amalgams with mercury and alloys with gold, iron, caesium, sodium, and potassium, rubidium has a very low ionization energy of only 406 kJ/mol. Rubidium and potassium show a very similar purple color in the flame test, rubidium silver iodide has the highest room temperature conductivity of any known ionic crystal, a property exploited in thin film batteries and other applications. Rubidium forms a number of oxides when exposed to air, including rubidium monoxide, Rb6O, rubidium forms salts with halides, producing rubidium fluoride, rubidium chloride, rubidium bromide, and rubidium iodide. Although rubidium is monoisotopic, rubidium in the Earths crust is composed of two isotopes, the stable 85Rb and the radioactive 87Rb, natural rubidium is radioactive, with specific activity of about 670 Bq/g, enough to significantly expose a photographic film in 110 days. Twenty four additional rubidium isotopes have been synthesized with half-lives of less than 3 months, Rubidium-87 has a half-life of 48. 8×109 years, which is more than three times the age of the universe of ×109 years, making it a primordial nuclide. It readily substitutes for potassium in minerals, and is fairly widespread
6.
Caesium
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Caesium or cesium is a chemical element with symbol Cs and atomic number 55. It is a soft, silvery-gold alkali metal with a point of 28.5 °C. Caesium is a metal and has physical and chemical properties similar to those of rubidium and potassium. The metal is extremely reactive and pyrophoric, reacting with water even at −116 °C, Caesium is one of the most reactive elements of all, even more reactive than fluorine, the most reactive nonmetal. It is the least electronegative element, with a value of 0.79 on the Pauling scale and it has only one stable isotope, caesium-133. Caesium is mined mostly from pollucite, while the radioisotopes, especially caesium-137, the German chemist Robert Bunsen and physicist Gustav Kirchhoff discovered caesium in 1860 by the newly developed method of flame spectroscopy. The first small-scale applications for caesium were as a getter in vacuum tubes, since then, caesium has been widely used in highly accurate atomic clocks. The radioactive isotope caesium-137 has a half-life of about 30 years and is used in applications, industrial gauges. Although the element is only toxic, the metal is a hazardous material. It is a ductile, pale metal, which darkens in the presence of trace amounts of oxygen. When in the presence of oil, it loses its metallic lustre and takes on a duller. It has a point of 28.4 °C, making it one of the few elemental metals that are liquid near room temperature. Mercury is the elemental metal with a known melting point lower than caesium. In addition, the metal has a low boiling point,641 °C. Its compounds burn with a blue or violet colour, Caesium forms alloys with the other alkali metals, gold, and mercury. At temperatures below 650 °C, it does not alloy with cobalt, iron, molybdenum, nickel, platinum, tantalum and it forms well-defined intermetallic compounds with antimony, gallium, indium, and thorium, which are photosensitive. It mixes with all the alkali metals, the alloy with a molar distribution of 41% caesium, 47% potassium. A few amalgams have been studied, CsHg 2 is black with a metallic lustre, while CsHg is golden-coloured
7.
Francium
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Francium is a chemical element with symbol Fr and atomic number 87. It used to be known as eka-caesium and actinium K and it is the second-least electronegative element, behind only caesium, and is the second rarest naturally occurring element. Francium is a radioactive metal that decays into astatine, radium. As an alkali metal, it has one valence electron, bulk francium has never been viewed. Obtaining such a sample is highly improbable, since the heat of decay would immediately vaporize any viewable quantity of the element. Francium was discovered by Marguerite Perey in France in 1939 and it was the last element first discovered in nature, rather than by synthesis. Outside the laboratory, francium is extremely rare, with trace amounts found in uranium and thorium ores, as little as 20–30 g exists at any given time throughout the Earths crust, the other isotopes are entirely synthetic. The largest amount produced in the laboratory was a cluster of more than 300,000 atoms, Francium is one of the most unstable of the naturally occurring elements, its longest-lived isotope, francium-223, has a half-life of only 22 minutes. All isotopes of francium decay into astatine, radium, or radon, francium-223 also has a shorter half-life than the longest-lived isotope of each synthetic element up to and including element 105, dubnium. Francium is an alkali metal whose chemical properties resemble those of caesium. A heavy element with a valence electron, it has the highest equivalent weight of any element. Liquid francium—if created—should have a surface tension of 0.05092 N/m at its melting point, franciums melting point was calculated to be around 27 °C. The melting point is uncertain because of the extreme rarity and radioactivity. Thus, the boiling point value of 677 °C is also uncertain. Francium should also have an electron affinity than caesium and the Fr− ion should be more polarizable than the Cs− ion. The CsFr molecule is predicted to have francium at the end of the dipole. Francium superoxide is expected to have a covalent character than its lighter congeners. Francium coprecipitates with caesium salts, such as caesium perchlorate
8.
Alkaline earth metal
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The alkaline earth metals are six chemical elements in column 2 of the Periodic table. They are beryllium, magnesium, calcium, strontium, barium, the elements have very similar properties, they are all shiny, silvery-white, somewhat reactive metals at standard temperature and pressure. All the discovered alkaline earth metals occur in nature, experiments have been conducted to attempt the synthesis of element 120, the next potential member of the group, but they have all met with failure. The chemistry of radium is not well-established due to its radioactivity, thus, the alkaline earth metals are all silver-colored and soft, and have relatively low densities, melting points, and boiling points. In chemical terms, all of the alkaline metals react with the halogens to form the earth metal halides. All the alkaline earth metals except beryllium also react with water to form strongly alkaline hydroxides and, thus, the heavier alkaline earth metals react more vigorously than the lighter ones. The second ionization energy of all of the metals is also somewhat low. Beryllium is an exception, It does not react with water or steam, all compounds that include beryllium have a covalent bond. Even the compound beryllium fluoride, which is the most ionic beryllium compound, has a low melting point and a low electrical conductivity when melted. The alkaline earth metals all react with the halogens to form ionic halides, such as calcium chloride, calcium, strontium, and barium react with water to produce hydrogen gas and their respective hydroxides, and also undergo transmetalation reactions to exchange ligands. The table below is a summary of the key physical and atomic properties of the alkaline earth metals, calcium-48 is the lightest nuclide to undergo double beta decay. The natural radioisotope of calcium, calcium-48, makes up about 0. 1874% of natural calcium, barium-130 makes up approximately 0. 1062% of natural barium, and, thus, barium is weakly radioactive, as well. The alkaline earth metals are named after their oxides, the alkaline earths, whose old-fashioned names were beryllia, magnesia, lime, strontia and these oxides are basic when combined with water. Earth is an old term applied by early chemists to nonmetallic substances that are insoluble in water, the realization that these earths were not elements but compounds is attributed to the chemist Antoine Lavoisier. In his Traité Élémentaire de Chimie of 1789 he called them salt-forming earth elements, later, he suggested that the alkaline earths might be metal oxides, but admitted that this was mere conjecture. The calcium compounds calcite and lime have been known and used since prehistoric times, the same is true for the beryllium compounds beryl and emerald. The other compounds of the alkaline earth metals were discovered starting in the early 15th century, the magnesium compound magnesium sulfate was first discovered in 1618 by a farmer at Epsom in England. Strontium carbonate was discovered in minerals in the Scottish village of Strontian in 1790, the last element is the least abundant, radioactive radium, which was extracted from uraninite in 1898
9.
Beryllium
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Beryllium is a chemical element with symbol Be and atomic number 4. It is a rare element in the universe, usually occurring as a product of the spallation of larger atomic nuclei that have collided with cosmic rays. Within the cores of stars beryllium is depleted as it is fused and it is a divalent element which occurs naturally only in combination with other elements in minerals. Notable gemstones which contain beryllium include beryl and chrysoberyl, as a free element it is a steel-gray, strong, lightweight and brittle alkaline earth metal. Beryllium improves many physical properties when added as an element to aluminium, copper, iron. Beryllium does not form oxides until it reaches high temperatures. Tools made of copper alloys are strong and hard and do not create sparks when they strike a steel surface. The high thermal conductivities of beryllium and beryllium oxide have led to their use in thermal management applications, Beryllium is a steel gray and hard metalloid that is brittle at room temperature and has a close-packed hexagonal crystal structure. It has exceptional stiffness and a high melting point. The modulus of elasticity of beryllium is approximately 50% greater than that of steel, the combination of this modulus and a relatively low density results in an unusually fast sound conduction speed in beryllium – about 12.9 km/s at ambient conditions. Other significant properties are high specific heat and thermal conductivity, which make beryllium the metal with the best heat dissipation characteristics per unit weight, in combination with the relatively low coefficient of linear thermal expansion, these characteristics result in a unique stability under conditions of thermal loading. Naturally occurring beryllium, save for slight contamination by cosmogenic radioisotopes, is essentially pure beryllium-9, Beryllium has a large scattering cross section for high-energy neutrons, about 6 barns for energies above approximately 10 keV. The single primordial beryllium isotope 9Be also undergoes a neutron reaction with neutron energies over about 1.9 MeV, to produce 8Be, thus, for high-energy neutrons, beryllium is a neutron multiplier, releasing more neutrons than it absorbs. Beryllium also releases neutrons under bombardment by gamma rays.8 seconds, β− is an electron, tritium is a radioisotope of concern in nuclear reactor waste streams. As a metal, beryllium is transparent to most wavelengths of X-rays and gamma rays, making it useful for the windows of X-ray tubes. Both stable and unstable isotopes of beryllium are created in stars, primordial beryllium contains only one stable isotope, 9Be, and therefore beryllium is a monoisotopic element. Radioactive cosmogenic 10Be is produced in the atmosphere of the Earth by the cosmic ray spallation of oxygen, 10Be accumulates at the soil surface, where its relatively long half-life permits a long residence time before decaying to boron-10. The production of 10Be is inversely proportional to activity, because increased solar wind during periods of high solar activity decreases the flux of galactic cosmic rays that reach the Earth
10.
Magnesium
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Magnesium is a chemical element with symbol Mg and atomic number 12. Magnesium is the ninth most abundant element in the universe and it is produced in large, aging stars from the sequential addition of three helium nuclei to a carbon nucleus. When such stars explode as supernovas, much of the magnesium is expelled into the medium where it may recycle into new star systems. Magnesium is the eighth most abundant element in the Earths crust and the fourth most common element in the Earth, making up 13% of the planets mass and it is the third most abundant element dissolved in seawater, after sodium and chlorine. Magnesium occurs naturally only in combination with elements, where it invariably has a +2 oxidation state. The free element can be produced artificially, and is highly reactive, the free metal burns with a characteristic brilliant-white light. The metal is now obtained mainly by electrolysis of magnesium salts obtained from brine, Magnesium is less dense than aluminium, and the alloy is prized for its combination of lightness and strength. Magnesium is the eleventh most abundant element by mass in the body and is essential to all cells. Magnesium ions interact with polyphosphate compounds such as ATP, DNA, hundreds of enzymes require magnesium ions to function. Magnesium compounds are used medicinally as common laxatives, antacids, elemental magnesium is a gray-white lightweight metal, two-thirds the density of aluminium. Magnesium has the lowest melting and the lowest boiling point 1,363 K of all the alkaline earth metals, Magnesium reacts with water at room temperature, though it reacts much more slowly than calcium, a similar group 2 metal. When submerged in water, hydrogen bubbles form slowly on the surface of the metal—though, if powdered, the reaction occurs faster with higher temperatures. Magnesiums reversible reaction with water can be harnessed to store energy, Magnesium also reacts exothermically with most acids such as hydrochloric acid, producing the metal chloride and hydrogen gas, similar to the HCl reaction with aluminium, zinc, and many other metals. Magnesium is highly flammable, especially when powdered or shaved into thin strips, flame temperatures of magnesium and magnesium alloys can reach 3,100 °C, although flame height above the burning metal is usually less than 300 mm. Once ignited, such fires are difficult to extinguish, with combustion continuing in nitrogen, carbon dioxide, Magnesium may also be used as an igniter for thermite, a mixture of aluminium and iron oxide powder that ignites only at a very high temperature. When burning in air, magnesium produces a light that includes strong ultraviolet wavelengths. Magnesium powder was used for illumination in the early days of photography. Later, magnesium filament was used in electrically ignited single-use photography flashbulbs, Magnesium powder is used in fireworks and marine flares where a brilliant white light is required
11.
Calcium
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Calcium is a chemical element with symbol Ca and atomic number 20. Calcium is a soft grayish-yellow alkaline earth metal, fifth-most-abundant element by mass in the Earths crust, the ion Ca2+ is also the fifth-most-abundant dissolved ion in seawater by both molarity and mass, after sodium, chloride, magnesium, and sulfate. Free calcium metal is too reactive to occur in nature, Calcium is produced in supernova nucleosynthesis. Calcium is a trace element in living organisms. It is the most abundant metal by mass in animals, and it is an important constituent of bone, teeth. In cell biology, the movement of the calcium ion into, Calcium carbonate and calcium citrate are often taken as dietary supplements. Calcium is on the World Health Organizations List of Essential Medicines, Calcium has a wide variety of applications, almost all of which are associated with calcium compounds and salts. Calcium metal is used as a deoxidizer, desulfurizer, and decarbonizer for production of ferrous and nonferrous alloys. In steelmaking and production of iron, Ca reacts with oxygen, Calcium carbonate is used in manufacturing cement and mortar, lime, limestone and aids in production in the glass industry. It also has chemical and optical uses as mineral specimens in toothpastes, Calcium hydroxide solution is used to detect the presence of carbon dioxide in a gas sample bubbled through a solution. The solution turns cloudy where CO2 is present, Calcium arsenate is used in insecticides. Calcium carbide is used to make acetylene gas and various plastics, Calcium chloride is used in ice removal and dust control on dirt roads, as a conditioner for concrete, as an additive in canned tomatoes, and to provide body for automobile tires. Calcium citrate is used as a food preservative, Calcium cyclamate is used as a sweetening agent in several countries. In the United States, it has been outlawed as a suspected carcinogen, Calcium gluconate is used as a food additive and in vitamin pills. Calcium hypochlorite is used as a swimming pool disinfectant, as an agent, as an ingredient in deodorant. Calcium permanganate is used in rocket propellant, textile production, as a water sterilizing agent. Calcium phosphate is used as a supplement for animal feed, fertilizer, in production for dough and yeast products, in the manufacture of glass. Calcium phosphide is used in fireworks, rodenticide, torpedoes, Calcium sulfate is used as common blackboard chalk, as well as, in its hemihydrate form, Plaster of Paris
12.
Strontium
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Strontium is a chemical element with symbol Sr and atomic number 38. An alkaline earth metal, strontium is a soft silver-white or yellowish metallic element that is highly reactive chemically, the metal forms a dark oxide layer when it is exposed to air. Strontium has physical and chemical properties similar to those of its two neighbors in the periodic table, calcium and barium. It occurs naturally in the minerals celestine, strontianite, and putnisite, natural stable strontium, on the other hand, is not hazardous to health. Strontium was first isolated as a metal in 1808 by Humphry Davy using the then-newly discovered process of electrolysis, the production of sugar from sugar beet was in the 19th century the largest application of strontium. At the peak of production of cathode ray tubes, as much as 75 percent of strontium consumption in the United States was used for the faceplate glass. With the displacement of cathode ray tubes by other display methods, Strontium is a divalent silvery metal with a pale yellow tint whose properties are mostly intermediate between and similar to those of its group neighbors calcium and barium. It is softer than calcium and harder than barium and its melting and boiling points are lower than those of calcium, barium continues this downward trend in the melting point, but not in the boiling point. The density of strontium is similarly intermediate between those of calcium and barium, three allotropes of metallic strontium exist, with transition points at 235 and 540 °C. The standard electrode potential for the Sr2+/Sr couple is −2.89 V, Strontium is intermediate between calcium and barium in its reactivity toward water, with which it reacts on contact to produce strontium hydroxide and hydrogen gas. Strontium metal burns in air to produce both strontium oxide and strontium nitride, but since it does not react with nitrogen below 380 °C, at room temperature, it forms only the oxide spontaneously. Besides the simple oxide SrO, the peroxide SrO2 can be made by oxidation of strontium metal under a high pressure of oxygen. Strontium hydroxide, Sr2, is a base, though it is not as strong as the hydroxides of barium or the alkali metals. Due to the size of the heavy s-block elements, including strontium. Organostrontium compounds contain one or more strontium–carbon bonds and they have been reported as intermediates in Barbier-type reactions. Organostrontium compounds tend to be similar to organoeuropium or organosamarium compounds due to the similar ionic radii of these elements. Most of these compounds can only be prepared at low temperatures, because of its extreme reactivity with oxygen and water, this element occurs naturally only in compounds with other elements, such as in the minerals strontianite and celestine. It is kept under a liquid such as mineral oil or kerosene to prevent oxidation
13.
Barium
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Barium is a chemical element with symbol Ba and atomic number 56. It is the element in Group 2, a soft silvery metallic alkaline earth metal. Because of its chemical reactivity, barium is never found in nature as a free element. Its hydroxide, known in history as baryta, does not occur as a mineral. The most common naturally occurring minerals of barium are barite and witherite, the barium name originates from the alchemical derivative baryta, from Greek βαρύς, meaning heavy. Baric is the form of barium. Barium was identified as a new element in 1774, but not reduced to a metal until 1808 with the advent of electrolysis, historically, it was used as a getter for vacuum tubes. It is a component of YBCO and electroceramics, and is added to steel, Barium compounds are added to fireworks to impart a green color. Barium sulfate is used as an additive to oil well drilling fluid, as well as in a purer form. The soluble barium ion and soluble compounds are poisonous, and have used as rodenticides. Barium is a soft, silvery-white metal, with a slight golden shade when ultrapure, the silvery-white color of barium metal rapidly vanishes upon oxidation in air yielding a dark gray oxide layer. Barium has a specific weight and good electrical conductivity. Ultrapure barium is very difficult to prepare, and therefore properties of barium have not been accurately measured yet. At room temperature and pressure, barium has a cubic structure, with a barium–barium distance of 503 picometers. It is a soft metal with a Mohs hardness of 1.25. Its melting temperature of 1,000 K is intermediate between those of the strontium and heavier radium, however, its boiling point of 2,170 K exceeds that of strontium. The density is again intermediate between those of strontium and radium, Barium is chemically similar to magnesium, calcium, and strontium, but even more reactive. It always exhibits the oxidation state of +2, except in a few rare, reactions with chalcogens are highly exothermic, the reaction with oxygen or air occurs at room temperature, and therefore barium is stored under oil or in an inert atmosphere
14.
Radium
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Radium is a chemical element with symbol Ra and atomic number 88. It is the element in group 2 of the periodic table. Pure radium is silvery-white, but it combines with nitrogen on exposure to air. All isotopes of radium are highly radioactive, with the most stable isotope being radium-226, when radium decays, ionizing radiation is a product, which can excite fluorescent chemicals and cause radioluminescence. Radium, in the form of chloride, was discovered by Marie. They extracted the radium compound from uraninite and published the discovery at the French Academy of Sciences five days later, Radium was isolated in its metallic state by Marie Curie and André-Louis Debierne through the electrolysis of radium chloride in 1911. In nature, radium is found in uranium and thorium ores in trace amounts as small as a seventh of a gram per ton of uraninite. Radium is not necessary for living organisms, and adverse effects are likely when it is incorporated into biochemical processes because of its radioactivity. Today, these applications are no longer in vogue because radiums toxicity has since become known. Radium is the heaviest known alkaline earth metal and is the only member of its group. Its physical and chemical properties most closely resemble its lighter congener barium, pure radium is a volatile silvery-white metal, although its lighter congeners calcium, strontium, and barium have a slight yellow tint. Its color rapidly vanishes in air, yielding a layer of radium nitride. Its melting point is either 700 °C or 960 °C and its point is 1,737 °C. Both of these values are lower than those of barium. Like barium and the metals, radium crystallizes in the body-centered cubic structure at standard temperature and pressure. Radium has a density of 5, Radium, like barium, is a highly reactive metal and always exhibits its group oxidation state of +2. It forms the colorless Ra2+ cation in aqueous solution, which is highly basic, the values for barium and radium are almost exactly the same as those of the heavier alkali metals potassium, rubidium, and caesium. Solid radium compounds are white as radium ions provide no specific coloring, insoluble radium compounds coprecipitate with all barium, most strontium, and most lead compounds
15.
Transition metal
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Many scientists describe a transition metal as any element in the d-block of the periodic table, which includes groups 3 to 12 on the periodic table. In actual practice, the lanthanide and actinide series are also considered transition metals and are called inner transition metals. Cotton and Wilkinson expand the brief IUPAC definition by specifying which elements are included, as well as the elements of groups 4 to 11, they add scandium and yttrium in group 3 which have a partially filled d subshell in the metallic state. These last two elements are included even though they do not seem to possess the properties which are so characteristic of the transition metals in general. Lanthanum and actinium in Group 3 are however classified as lanthanides and actinides respectively and these elements are now known as the d-block. In the d-block the atoms of the elements have between 1 and 10 d electrons, Sc and Y in Group 3 are also generally recognized as transition metals. However the elements La–Lu and Ac–Lr and Group 12 attract different definitions from different authors, many chemistry textbooks and printed periodic tables classify La and Ac as Group 3 elements and transition metals, since their atomic ground-state configurations are s2d1 like Sc and Y. The elements Ce-Lu are considered as the series and Th-Lr as the actinide series. The two series together are classified as elements, or as inner transition elements. Some inorganic chemistry textbooks include La with the lanthanides and Ac with the actinides, a third classification defines the f-block elements as La-Yb and Ac-No, while placing Lu and Lr in Group 3. This is based on the Aufbau principle for filling electron subshells, in which 4f is filled before 5d, zinc, cadmium, and mercury are generally excluded from the transition metals as they have the electronic configuration d10s2, with no incomplete d shell. In the oxidation state +2 the ions have the electronic configuration d10, however, these elements can exist in other oxidation states, including the +1 oxidation state, as in the diatomic ion Hg2+2. The group 12 elements Zn, Cd and Hg may therefore, under certain rules, however, it is often convenient to include these elements in a discussion of the transition elements. Another example occurs in the Irving-Williams series of stability constants of complexes, although meitnerium, darmstadtium, and roentgenium are within the d-block and are expected to behave as transition metals, this has not yet been experimentally confirmed. The general electronic configuration of the elements is d1, 10n s1,2. The period 6 and 7 transition metals also add f1,14 electrons and this rule is however only approximate – it only holds for some of the transition elements, and only then in their neutral ground state. The d-sub-shell is the next-to-last sub-shell and is denoted as d -sub-shell, the number of s electrons in the outermost s sub-shell is generally one or two except palladium, with no electron in that s-sub shell in its ground state. The s-sub-shell in the shell is represented as the ns sub-shell
16.
Scandium
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Scandium is a chemical element with symbol Sc and atomic number 21. A silvery-white metallic d-block element, it has historically been classified as a rare earth element, together with yttrium. It was discovered in 1879 by spectral analysis of the minerals euxenite and gadolinite from Scandinavia, Scandium is present in most of the deposits of rare earth and uranium compounds, but it is extracted from these ores in only a few mines worldwide. Because of the low availability and the difficulties in the preparation of metallic scandium, the positive effects of scandium on aluminium alloys were discovered in the 1970s, and its use in such alloys remains its only major application. The global trade of scandium oxide is about 10 tonnes per year, the properties of scandium compounds are intermediate between those of aluminium and yttrium. A diagonal relationship exists between the behavior of magnesium and scandium, just as there is between beryllium and aluminium, in the chemical compounds of the elements in group 3, the predominant oxidation state is +3. Scandium is a metal with a silvery appearance. It develops a slightly yellowish or pinkish cast when oxidized by air and it is susceptible to weathering and dissolves slowly in most dilute acids. It does not react with a 1,1 mixture of acid and 48% hydrofluoric acid. Scandium turnings ignite in air with a brilliant yellow flame to form scandium oxide, in nature, scandium is found exclusively as the isotope 45Sc, which has a nuclear spin of 7/2. Thirteen radioisotopes have been characterized with the most stable being 46Sc, which has a half-life of 83.8 days, 47Sc,3.35 days, the positron emitter 44Sc,4 h, and 48Sc,43.7 hours. All of the radioactive isotopes have half-lives less than 4 hours. This element also has five meta states, with the most stable being 44mSc, the isotopes of scandium range from 36Sc to 60Sc. The primary decay mode at masses lower than the stable isotope, 45Sc, is electron capture. The primary decay products at atomic weights below 45Sc are calcium isotopes, in Earths crust, scandium is not rare. Estimates vary from 18 to 25 ppm, which is comparable to the abundance of cobalt, Scandium is only the 50th most common element on Earth, but it is the 23rd most common element in the Sun. However, scandium is distributed sparsely and occurs in trace amounts in many minerals, rare minerals from Scandinavia and Madagascar such as thortveitite, euxenite, and gadolinite are the only known concentrated sources of this element. Thortveitite can contain up to 45% of scandium in the form of scandium oxide, the stable form of scandium is created in supernovas via the r-process
17.
Titanium
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Titanium is a chemical element with symbol Ti and atomic number 22. It is a transition metal with a silver color, low density. Titanium is resistant to corrosion in sea water, aqua regia, titanium was discovered in Cornwall, Great Britain, by William Gregor in 1791, and it is named by Martin Heinrich Klaproth for the Titans of Greek mythology. The metal is extracted from its principal mineral ores by the Kroll, the most common compound, titanium dioxide, is a popular photocatalyst and is used in the manufacture of white pigments. Other compounds include titanium tetrachloride, a component of smoke screens and catalysts, and titanium trichloride, the two most useful properties of the metal are corrosion resistance and strength-to-density ratio, the highest of any metallic element. In its unalloyed condition, titanium is as strong as some steels, there are two allotropic forms and five naturally occurring isotopes of this element, 46Ti through 50Ti, with 48Ti being the most abundant. Although they have the number of valence electrons and are in the same group in the periodic table. As a metal, titanium is recognized for its high strength-to-weight ratio and it is a strong metal with low density that is quite ductile, lustrous, and metallic-white in color. The relatively high melting point makes it useful as a refractory metal and it is paramagnetic and has fairly low electrical and thermal conductivity. Commercial grades of titanium have ultimate tensile strength of about 434 MPa, equal to that of common, low-grade steel alloys, titanium is 60% denser than aluminium, but more than twice as strong as the most commonly used 6061-T6 aluminium alloy. Certain titanium alloys achieve tensile strengths of over 1400 MPa, however, titanium loses strength when heated above 430 °C. Titanium is not as hard as some grades of heat-treated steel, it is non-magnetic, machining requires precautions, because the material might gall unless sharp tools and proper cooling methods are used. Like steel structures, those made from titanium have a limit that guarantees longevity in some applications. The metal is an allotrope of an hexagonal α form that changes into a body-centered cubic β form at 882 °C. The specific heat of the α form increases dramatically as it is heated to this transition temperature but then falls, similar to zirconium and hafnium, an additional omega phase exists, which is thermodynamically stable at high pressures, but metastable at ambient pressures. This phase is usually hexagonal or trigonal and can be considered to be due to a soft longitudinal acoustic phonon of the β phase causing collapse of planes of atoms, like aluminium and magnesium, titanium metal and its alloys oxidize immediately upon exposure to air. Titanium readily reacts with oxygen at 1,200 °C in air and it is, however, slow to react with water and air at ambient temperatures because it forms a passive oxide coating that protects the bulk metal from further oxidation. When it first forms, this layer is only 1–2 nm thick but continues to grow slowly
18.
Vanadium
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Vanadium is a chemical element with symbol V and atomic number 23. It is a hard, silvery grey, ductile, and malleable transition metal, the elemental metal is rarely found in nature, but once isolated artificially, the formation of an oxide layer stabilizes the free metal somewhat against further oxidation. Four years later, however, he was convinced by other scientists that erythronium was identical to chromium, both names were attributed to the wide range of colors found in vanadium compounds. Del Rios lead mineral was later renamed vanadinite for its vanadium content, in 1867 Henry Enfield Roscoe obtained the pure element. Vanadium occurs naturally in about 65 different minerals and in fossil fuel deposits and it is produced in China and Russia from steel smelter slag, other countries produce it either from the flue dust of heavy oil, or as a byproduct of uranium mining. It is mainly used to produce specialty steel alloys such as high-speed tool steels, the most important industrial vanadium compound, vanadium pentoxide, is used as a catalyst for the production of sulfuric acid. Large amounts of ions are found in a few organisms. The oxide and some salts of vanadium have moderate toxicity. Particularly in the ocean, vanadium is used by life forms as an active center of enzymes. Vanadium was discovered by Andrés Manuel del Río, a Spanish-Mexican mineralogist, Del Río extracted the element from a sample of Mexican brown lead ore, later named vanadinite. He found that its salts exhibit a variety of colors. Later, Del Río renamed the element erythronium because most of the salts turned red upon heating, Del Río accepted Collet-Descotils statement and retracted his claim. In 1831, the Swedish chemist Nils Gabriel Sefström rediscovered the element in a new oxide he found working with iron ores. Later that same year, Friedrich Wöhler confirmed del Ríos earlier work, Sefström chose a name beginning with V, which had not been assigned to any element yet. He called the element vanadium after Old Norse Vanadís, because of the many beautifully colored chemical compounds it produces, in 1831, the geologist George William Featherstonhaugh suggested that vanadium should be renamed rionium after del Río, but this suggestion was not followed. The isolation of vanadium metal proved difficult, in 1831, Berzelius reported the production of the metal, but Henry Enfield Roscoe showed that Berzelius had in fact produced the nitride, vanadium nitride. Roscoe eventually produced the metal in 1867 by reduction of chloride, VCl2. In 1927, pure vanadium was produced by reducing vanadium pentoxide with calcium, the first large-scale industrial use of vanadium was in the steel alloy chassis of the Ford Model T, inspired by French race cars
19.
Chromium
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Chromium is a chemical element with symbol Cr and atomic number 24. It is the first element in Group 6 and it is a steely-grey, lustrous, hard and brittle metal which takes a high polish, resists tarnishing, and has a high melting point. The name of the element is derived from the Greek word χρῶμα, chrōma, meaning color, Chromium metal is of high value for its high corrosion resistance and hardness. A major development was the discovery that steel could be highly resistant to corrosion and discoloration by adding metallic chromium to form stainless steel. Stainless steel and chrome plating together comprise 85% of the commercial use, trivalent chromium ion is an essential nutrient in trace amounts in humans for insulin, sugar and lipid metabolism, although the issue is debated. While chromium metal and Cr ions are not considered toxic, hexavalent chromium is toxic and carcinogenic, abandoned chromium production sites often require environmental cleanup. Chromium is remarkable for its properties, it is the only elemental solid which shows antiferromagnetic ordering at room temperature. Above 38 °C, it changes to paramagnetic, Chromium metal left standing in air is passivated by oxidation, forming a thin, protective, surface layer. This layer is a structure only a few molecules thick. It is very dense, and prevents the diffusion of oxygen into the underlying metal and this is different from the oxide that forms on iron and carbon steel, through which elemental oxygen continues to migrate, reaching the underlying material to cause incessant rusting. Passivation can be enhanced by short contact with oxidizing acids like nitric acid, passivated chromium is stable against acids. Passivation can be removed with a reducing agent that destroys the protective oxide layer on the metal. Chromium metal treated in this way readily dissolves in weak acids, Chromium, unlike such metals as iron and nickel, does not suffer from hydrogen embrittlement. However, it suffer from nitrogen embrittlement, reacting with nitrogen from air. Chromium is the 22nd most abundant element in Earths crust with a concentration of 100 ppm. Chromium compounds are found in the environment from the erosion of chromium-containing rocks, Chromium is mined as chromite ore. About two-fifths of the ores and concentrates in the world are produced in South Africa, while Kazakhstan, India, Russia. Untapped chromite deposits are plentiful, but geographically concentrated in Kazakhstan, although rare, deposits of native chromium exist
20.
Manganese
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Manganese is a chemical element with symbol Mn and atomic number 25. It is not found as an element in nature, it is often found in minerals in combination with iron. Manganese is a metal with important industrial metal alloy uses, particularly in stainless steels, by the mid-18th century, Swedish chemist Carl Wilhelm Scheele had used pyrolusite to produce chlorine. Scheele and others were aware that pyrolusite contained a new element, johan Gottlieb Gahn was the first to isolate an impure sample of manganese metal in 1774, which he did by reducing the dioxide with carbon. Manganese phosphating is used for rust and corrosion prevention on steel, ionized manganese is used industrially as pigments of various colors, which depend on the oxidation state of the ions. The permanganates of alkali and alkaline earth metals are powerful oxidizers, Manganese dioxide is used as the cathode material in zinc-carbon and alkaline batteries. In biology, manganese ions function as cofactors for a variety of enzymes with many functions. Manganese enzymes are essential in detoxification of superoxide free radicals in organisms that must deal with elemental oxygen. Manganese also functions in the complex of photosynthetic plants. The element is a trace mineral for all known living organisms but is a neurotoxin. In larger amounts, and apparently with far greater effectiveness through inhalation, Manganese is a silvery-gray metal that resembles iron. It is hard and very brittle, difficult to fuse, Manganese metal and its common ions are paramagnetic. Manganese tarnishes slowly in air and oxidizes like iron in water containing dissolved oxygen, naturally occurring manganese is composed of one stable isotope, 55Mn. Eighteen radioisotopes have been isolated and described, the most stable being 53Mn with a half-life of 3.7 million years, 54Mn with a half-life of 312.3 days, and 52Mn with a half-life of 5.591 days. All of the radioactive isotopes have half-lives of less than three hours, and the majority of less than one minute. Manganese also has three meta states, Manganese is part of the iron group of elements, which are thought to be synthesized in large stars shortly before the supernova explosion. 53Mn decays to 53Cr with a half-life of 3.7 million years, because of its relatively short half-life, 53Mn is relatively rare, produced by cosmic rays impact on iron. Manganese isotopic contents are combined with chromium isotopic contents and have found application in isotope geology
21.
Iron
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Iron is a chemical element with symbol Fe and atomic number 26. It is a metal in the first transition series and it is by mass the most common element on Earth, forming much of Earths outer and inner core. It is the fourth most common element in the Earths crust, like the other group 8 elements, ruthenium and osmium, iron exists in a wide range of oxidation states, −2 to +6, although +2 and +3 are the most common. Elemental iron occurs in meteoroids and other low oxygen environments, but is reactive to oxygen, fresh iron surfaces appear lustrous silvery-gray, but oxidize in normal air to give hydrated iron oxides, commonly known as rust. Unlike the metals that form passivating oxide layers, iron oxides occupy more volume than the metal and thus flake off, Iron metal has been used since ancient times, although copper alloys, which have lower melting temperatures, were used even earlier in human history. Pure iron is soft, but is unobtainable by smelting because it is significantly hardened and strengthened by impurities, in particular carbon. A certain proportion of carbon steel, which may be up to 1000 times harder than pure iron. Crude iron metal is produced in blast furnaces, where ore is reduced by coke to pig iron, further refinement with oxygen reduces the carbon content to the correct proportion to make steel. Steels and iron alloys formed with metals are by far the most common industrial metals because they have a great range of desirable properties. Iron chemical compounds have many uses, Iron oxide mixed with aluminium powder can be ignited to create a thermite reaction, used in welding and purifying ores. Iron forms binary compounds with the halogens and the chalcogens, among its organometallic compounds is ferrocene, the first sandwich compound discovered. Iron plays an important role in biology, forming complexes with oxygen in hemoglobin and myoglobin. Iron is also the metal at the site of many important redox enzymes dealing with cellular respiration and oxidation and reduction in plants. A human male of average height has about 4 grams of iron in his body and this iron is distributed throughout the body in hemoglobin, tissues, muscles, bone marrow, blood proteins, enzymes, ferritin, hemosiderin, and transport in plasma. The mechanical properties of iron and its alloys can be evaluated using a variety of tests, including the Brinell test, Rockwell test, the data on iron is so consistent that it is often used to calibrate measurements or to compare tests. An increase in the content will cause a significant increase in the hardness. Maximum hardness of 65 Rc is achieved with a 0. 6% carbon content, because of the softness of iron, it is much easier to work with than its heavier congeners ruthenium and osmium. Because of its significance for planetary cores, the properties of iron at high pressures and temperatures have also been studied extensively
22.
Cobalt
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Cobalt is a chemical element with symbol Co and atomic number 27. Like nickel, cobalt is found in the Earths crust only in chemically combined form, the free element, produced by reductive smelting, is a hard, lustrous, silver-gray metal. In 1735, such ores were found to be reducible to a new metal, today, some cobalt is produced specifically from various metallic-lustered ores, for example cobaltite, but the main source of the element is as a by-product of copper and nickel mining. The copper belt in the Democratic Republic of the Congo, Central African Republic, cobalt is primarily used in the preparation of magnetic, wear-resistant and high-strength alloys. The compounds, cobalt silicate and cobalt aluminate give a deep blue color to glass, ceramics, inks, paints. Cobalt occurs naturally as only one isotope, cobalt-59. Cobalt-60 is an important radioisotope, used as a radioactive tracer. Cobalt is the center of coenzymes called cobalamins, the most common example of which is vitamin B12. As such, it is a trace dietary mineral for all animals. Cobalt in inorganic form is also a micronutrient for bacteria, algae, cobalt is a ferromagnetic metal with a specific gravity of 8.9. The Curie temperature is 1,115 °C and the moment is 1. 6–1.7 Bohr magnetons per atom. Cobalt has a relative permeability two-thirds that of iron, metallic cobalt occurs as two crystallographic structures, hcp and fcc. The ideal transition temperature between the hcp and fcc structures is 450 °C, but in practice, the difference is so small that random intergrowth of the two is common. Cobalt is a weakly reducing metal that is protected from oxidation by an oxide film. It is attacked by halogens and sulfur, heating in oxygen produces Co3O4 which loses oxygen at 900 °C to give the monoxide CoO. The metal reacts with fluorine at 520 K to give CoF3, with chlorine, bromine and iodine and it does not react with hydrogen gas or nitrogen gas even when heated, but it does react with boron, carbon, phosphorus, arsenic and sulfur. At ordinary temperatures, it reacts slowly with mineral acids, and very slowly with moist, common oxidation states of cobalt include +2 and +3, although compounds with oxidation states ranging from −3 to +5 are also known. A common oxidation state for simple compounds is +2 and these salts form the pink-colored metal aquo complex 2+ in water
23.
Nickel
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Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a golden tinge. Nickel belongs to the metals and is hard and ductile. Meteoric nickel is found in combination with iron, a reflection of the origin of elements as major end products of supernova nucleosynthesis. An iron–nickel mixture is thought to compose Earths inner core, use of nickel has been traced as far back as 3500 BCE. Nickel was first isolated and classified as an element in 1751 by Axel Fredrik Cronstedt. The elements name comes from a mischievous sprite of German miner mythology, Nickel, an economically important source of nickel is the iron ore limonite, which often contains 1–2% nickel. Nickels other important ore minerals include garnierite, and pentlandite, major production sites include the Sudbury region in Canada, New Caledonia in the Pacific, and Norilsk in Russia. Nickel is slowly oxidized by air at room temperature and is considered corrosion-resistant, historically, it has been used for plating iron and brass, coating chemistry equipment, and manufacturing certain alloys that retain a high silvery polish, such as German silver. About 6% of world production is still used for corrosion-resistant pure-nickel plating. Nickel-plated objects sometimes provoke nickel allergy, Nickel has been widely used in coins, though its rising price has led to some replacement with cheaper metals in recent years. Nickel is one of four elements that are ferromagnetic around room temperature, alnico permanent magnets based partly on nickel are of intermediate strength between iron-based permanent magnets and rare-earth magnets. The metal is valuable in modern times chiefly in alloys, about 60% of world production is used in nickel-steels, other common alloys and some new superalloys comprise most of the remainder of world nickel use, with chemical uses for nickel compounds consuming less than 3% of production. As a compound, nickel has a number of chemical manufacturing uses. Nickel is a nutrient for some microorganisms and plants that have enzymes with nickel as an active site. Nickel is a metal with a slight golden tinge that takes a high polish. It is one of four elements that are magnetic at or near room temperature. Its Curie temperature is 355 °C, meaning that bulk nickel is non-magnetic above this temperature, the unit cell of nickel is a face-centered cube with the lattice parameter of 0.352 nm, giving an atomic radius of 0.124 nm
24.
Copper
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Copper is a chemical element with symbol Cu and atomic number 29. It is a soft, malleable, and ductile metal with high thermal and electrical conductivity. A freshly exposed surface of copper has a reddish-orange color. Copper is one of the few metals that occur in nature in directly usable metallic form as opposed to needing extraction from an ore and this led to very early human use, from c.8000 BC. Copper used in buildings, usually for roofing, oxidizes to form a green verdigris, Copper is sometimes used in decorative art, both in its elemental metal form and in compounds as pigments. Copper compounds are used as agents, fungicides, and wood preservatives. Copper is essential to all living organisms as a trace dietary mineral because it is a key constituent of the enzyme complex cytochrome c oxidase. In molluscs and crustaceans, copper is a constituent of the blood pigment hemocyanin, replaced by the hemoglobin in fish. In humans, copper is found mainly in the liver, muscle, the adult body contains between 1.4 and 2.1 mg of copper per kilogram of body weight. The filled d-shells in these elements contribute little to interatomic interactions, unlike metals with incomplete d-shells, metallic bonds in copper are lacking a covalent character and are relatively weak. This observation explains the low hardness and high ductility of single crystals of copper, at the macroscopic scale, introduction of extended defects to the crystal lattice, such as grain boundaries, hinders flow of the material under applied stress, thereby increasing its hardness. For this reason, copper is supplied in a fine-grained polycrystalline form. The softness of copper partly explains its high conductivity and high thermal conductivity. The maximum permissible current density of copper in open air is approximately 3. 1×106 A/m2 of cross-sectional area, Copper is one of a few metallic elements with a natural color other than gray or silver. Pure copper is orange-red and acquires a reddish tarnish when exposed to air, as with other metals, if copper is put in contact with another metal, galvanic corrosion will occur. A green layer of verdigris can often be seen on old structures, such as the roofing of many older buildings. Copper tarnishes when exposed to sulfur compounds, with which it reacts to form various copper sulfides. There are 29 isotopes of copper, 63Cu and 65Cu are stable, with 63Cu comprising approximately 69% of naturally occurring copper, both have a spin of 3⁄2
25.
Yttrium
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Yttrium is a chemical element with symbol Y and atomic number 39. It is a transition metal chemically similar to the lanthanides and has often been classified as a rare earth element. Yttrium is almost always found in combination with elements in rare earth minerals. 89Y is the stable isotope, and the only isotope found in the Earths crust. In 1787, Carl Axel Arrhenius found a new mineral near Ytterby in Sweden and named it ytterbite, johan Gadolin discovered yttriums oxide in Arrhenius sample in 1789, and Anders Gustaf Ekeberg named the new oxide yttria. Elemental yttrium was first isolated in 1828 by Friedrich Wöhler, the most important uses of yttrium are LEDs and phosphors, particularly the red phosphors in television set cathode ray tube displays. Yttrium has no biological role. Exposure to yttrium compounds can cause disease in humans. Yttrium is a soft, silver-metallic, lustrous and highly crystalline transition metal in group 3, yttrium is the first d-block element in the fifth period. The pure element is relatively stable in air in bulk form and this film can reach a thickness of 10 µm when yttrium is heated to 750 °C in water vapor. When finely divided, however, yttrium is very unstable in air, yttrium nitride is formed when the metal is heated to 1000 °C in nitrogen.5 to 67.5, placing it between the lanthanides gadolinium and erbium. It often also falls in the range for reaction order. Yttrium is so close in size to the yttrium group of heavy lanthanide ions that in solution. Even though the lanthanides are one row farther down the table than yttrium. As a trivalent transition metal, yttrium forms various inorganic compounds, generally in the state of +3. A good example is yttrium oxide, also known as yttria, yttrium forms a water-insoluble fluoride, hydroxide, and oxalate, but its bromide, chloride, iodide, nitrate and sulfate are all soluble in water. The Y3+ ion is colorless in solution because of the absence of electrons in the d and f electron shells, water readily reacts with yttrium and its compounds to form Y 2O3. Concentrated nitric and hydrofluoric acids do not rapidly attack yttrium, with halogens, yttrium forms trihalides such as yttrium fluoride, yttrium chloride, and yttrium bromide at temperatures above roughly 200 °C
26.
Zirconium
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Zirconium is a chemical element with symbol Zr and atomic number 40. The name of zirconium is taken from the name of the mineral zircon, the word zircon comes from the Persian word zargun زرگون, meaning gold-colored. It is a lustrous, grey-white, strong metal that resembles hafnium and, to a lesser extent. Zirconium is mainly used as a refractory and opacifier, although small amounts are used as an agent for its strong resistance to corrosion. Zirconium forms a variety of inorganic and organometallic compounds such as zirconium dioxide and zirconocene dichloride, five isotopes occur naturally, three of which are stable. Zirconium compounds have no biological role. Zirconium is a lustrous, greyish-white, soft, ductile and malleable metal that is solid at room temperature, though it is hard, in powder form, zirconium is highly flammable, but the solid form is much less prone to ignition. Zirconium is highly resistant to corrosion by alkalis, acids, salt water and other agents, however, it will dissolve in hydrochloric and sulfuric acid, especially when fluorine is present. Alloys with zinc are magnetic at less than 35 K, the melting point of zirconium is 1855 °C, and the boiling point is 4371 °C. Zirconium has an electronegativity of 1.33 on the Pauling scale, of the elements within the d-block, zirconium has the fourth lowest electronegativity after yttrium, lanthanum, and hafnium. At room temperature zirconium exhibits a hexagonally close-packed crystal structure, α-Zr, which changes to β-Zr, Zirconium exists in the β-phase until the melting point. Naturally occurring zirconium is composed of five isotopes, 90Zr, 91Zr, 92Zr and 94Zr are stable, although 94Zr is predicted to undergo double beta decay with a half-life of more than 1. 10×1017 years. 96Zr has a half-life of 2. 4×1019 years, and is the radioisotope of zirconium. Of these natural isotopes, 90Zr is the most common, making up 51. 45% of all zirconium, 96Zr is the least common, comprising only 2. 80% of zirconium. Twenty-eight artificial isotopes of zirconium have been synthesized, ranging in mass from 78 to 110. 93Zr is the longest-lived artificial isotope, with a half-life of 1. 53×106 years, 110Zr, the heaviest isotope of zirconium, is the most radioactive, with an estimated half-life of 30 milliseconds. Radioactive isotopes at or above mass number 93 decay by electron emission, the only exception is 88Zr, which decays by electron capture. Five isotopes of zirconium also exist as isomers, 83mZr, 85mZr, 89mZr, 90m1Zr, 90m2Zr and 91mZr
27.
Niobium
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Niobium, formerly columbium, is a chemical element with symbol Nb and atomic number 41. It is a soft, grey, ductile metal, which is often found in the pyrochlore mineral, the main commercial source for niobium. Its name comes from Greek mythology, specifically Niobe, who was the daughter of Tantalus, the name reflects the great similarity between the two elements in their physical and chemical properties, making them difficult to distinguish. The English chemist Charles Hatchett reported a new element similar to tantalum in 1801, in 1809, the English chemist William Hyde Wollaston wrongly concluded that tantalum and columbium were identical. The German chemist Heinrich Rose determined in 1846 that tantalum ores contain a second element, in 1864 and 1865, a series of scientific findings clarified that niobium and columbium were the same element, and for a century both names were used interchangeably. Niobium was officially adopted as the name of the element in 1949 and it was not until the early 20th century that niobium was first used commercially. Brazil is the producer of niobium and ferroniobium, an alloy of niobium. Niobium is used mostly in alloys, the largest part in special steel such as used in gas pipelines. Although these alloys contain a maximum of 0. 1%, the percentage of niobium enhances the strength of the steel. The temperature stability of niobium-containing superalloys is important for its use in jet and rocket engines, Niobium is used in various superconducting materials. These superconducting alloys, also containing titanium and tin, are used in the superconducting magnets of MRI scanners. Other applications of niobium include welding, nuclear industries, electronics, optics, numismatics, in the last two applications, the low toxicity and iridescence produced by anodization are highly desired properties. Niobium was identified by English chemist Charles Hatchett in 1801, the columbium discovered by Hatchett was probably a mixture of the new element with tantalum. Subsequently, there was confusion over the difference between columbium and the closely related tantalum. This confusion arose from the observed differences between tantalum and niobium. The claimed new elements pelopium, ilmenium, and dianium were in fact identical to niobium or mixtures of niobium and tantalum, articles on ilmenium continued to appear until 1871. De Marignac was the first to prepare the metal in 1864 and this use quickly became obsolete through the replacement of niobium with tungsten, which has a higher melting point. That niobium improves the strength of steel was first discovered in the 1920s, to end this confusion, the name niobium was chosen for element 41 at the 15th Conference of the Union of Chemistry in Amsterdam in 1949
28.
Molybdenum
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Molybdenum is a chemical element with symbol Mo and atomic number 42. The name is from Neo-Latin molybdaenum, from Ancient Greek Μόλυβδος molybdos, meaning lead, molybdenum minerals have been known throughout history, but the element was discovered in 1778 by Carl Wilhelm Scheele. The metal was first isolated in 1781 by Peter Jacob Hjelm, molybdenum does not occur naturally as a free metal on Earth, it is found only in various oxidation states in minerals. The free element, a metal with a gray cast, has the sixth-highest melting point of any element. It readily forms hard, stable carbides in alloys, and for this reason most of production of the element is used in steel alloys. Most molybdenum compounds have low solubility in water, but when molybdenum-bearing minerals contact oxygen and water, industrially, molybdenum compounds are used in high-pressure and high-temperature applications as pigments and catalysts. Molybdenum-bearing enzymes are by far the most common catalysts for breaking the chemical bond in atmospheric molecular nitrogen in the process of biological nitrogen fixation. At least 50 molybdenum enzymes are now known in bacteria and animals and these nitrogenases contain molybdenum in a form different from other molybdenum enzymes, which all contain fully oxidized molybdenum in a molybdenum cofactor. These various molybdenum cofactor enzymes are vital to the organisms, and molybdenum is an element for life in all higher eukaryote organisms. In its pure form, molybdenum is a metal with a Mohs hardness of 5.5. It has a point of 2,623 °C, of the naturally occurring elements, only tantalum, osmium, rhenium, tungsten. Weak oxidation of molybdenum starts at 300 °C and it has one of the lowest coefficients of thermal expansion among commercially used metals. The tensile strength of molybdenum wires increases about 3 times, from about 10 to 30 GPa, there are 35 known isotopes of molybdenum, ranging in atomic mass from 83 to 117, as well as four metastable nuclear isomers. Seven isotopes occur naturally, with masses of 92,94,95,96,97,98. Of these naturally occurring isotopes, only molybdenum-100 is unstable, molybdenum-98 is the most abundant isotope, comprising 24. 14% of all molybdenum. Molybdenum-100 has a half-life of about 1019 y and undergoes double beta decay into ruthenium-100, molybdenum isotopes with mass numbers from 111 to 117 all have half-lives of approximately 150 ns. All unstable isotopes of molybdenum decay into isotopes of niobium, technetium, as also noted below, the most common isotopic molybdenum application involves molybdenum-99, which is a fission product. It is a parent radioisotope to the short-lived gamma-emitting daughter radioisotope technetium-99m, in 2008, the Delft University of Technology applied for a patent on the molybdenum-98-based production of molybdenum-99
29.
Technetium
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Technetium is a chemical element with symbol Tc and atomic number 43. It is the lightest element of all isotopes are radioactive. Nearly all technetium is produced synthetically, and only minute amounts are found in the Earths crust, naturally occurring technetium is a spontaneous fission product in uranium ore or the product of neutron capture in molybdenum ores. The chemical properties of this silvery gray, crystalline transition metal are intermediate between rhenium and manganese, many of technetiums properties were predicted by Dmitri Mendeleev before the element was discovered. Mendeleev noted a gap in his table and gave the undiscovered element the provisional name ekamanganese. In 1937, technetium became the first predominantly artificial element to be produced and its short-lived gamma ray-emitting nuclear isomer—technetium-99m—is used in nuclear medicine for a wide variety of diagnostic tests. Technetium-99 is used as a source of beta particles. Long-lived technetium isotopes produced commercially are by-products of fission of uranium-235 in nuclear reactors and are extracted from nuclear fuel rods, from the 1860s through 1871, early forms of the periodic table proposed by Dmitri Mendeleev contained a gap between molybdenum and ruthenium. In 1871, Mendeleev predicted this missing element would occupy the empty place below manganese and have similar chemical properties, Mendeleev gave it the provisional name ekamanganese because the predicted element was one place down from the known element manganese. Many early researchers, both before and after the table was published, were eager to be the first to discover. Its location in the table suggested that it should be easier to find than other undiscovered elements, german chemists Walter Noddack, Otto Berg, and Ida Tacke reported the discovery of element 75 and element 43 in 1925, and named element 43 masurium. The group bombarded columbite with a beam of electrons and deduced element 43 was present by examining X-ray diffraction spectrograms, the wavelength of the X-rays produced is related to the atomic number by a formula derived by Henry Moseley in 1913. The team claimed to detect a faint X-ray signal at a wavelength produced by element 43, later experimenters could not replicate the discovery, and it was dismissed as an error for many years. Still, in 1933, a series of articles on the discovery of elements quoted the name masurium for element 43, whether the 1925 team actually did discover element 43 is still debated. The discovery of element 43 was finally confirmed in a December 1936 experiment at the University of Palermo in Sicily by Carlo Perrier, in mid-1936, Segrè visited the United States, first Columbia University in New York and then the Lawrence Berkeley National Laboratory in California. He persuaded cyclotron inventor Ernest Lawrence to let him back some discarded cyclotron parts that had become radioactive. Lawrence mailed him a molybdenum foil that had part of the deflector in the cyclotron. Segrè enlisted his colleague Perrier to attempt to prove, through comparative chemistry, in 1937 they succeeded in isolating the isotopes technetium-95m and technetium-97
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Ruthenium
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Ruthenium is a chemical element with symbol Ru and atomic number 44. It is a transition metal belonging to the platinum group of the periodic table. Like the other metals of the group, ruthenium is inert to most other chemicals. The Baltic German scientist Karl Ernst Claus discovered the element in 1844 and named it after his homeland, ruthenium is usually found as a minor component of platinum ores, the annual production is about 20 tonnes. Most ruthenium produced is used in wear-resistant electrical contacts and thick-film resistors, a minor application for ruthenium is in platinum alloys and as a chemistry catalyst. This anomaly is observed in the metals, niobium, rhodium. Ruthenium has four crystal modifications and does not tarnish unless subject to high temperatures, ruthenium dissolves in fused alkalis to give ruthenates, is not attacked by acids but is attacked by halogens at high temperatures. Indeed, ruthenium is most readily attacked by oxidizing agents, small amounts of ruthenium can increase the hardness of platinum and palladium. The corrosion resistance of titanium is increased markedly by the addition of an amount of ruthenium. The metal can be plated by electroplating and by thermal decomposition, a ruthenium-molybdenum alloy is known to be superconductive at temperatures below 10.6 K. Like iron but unlike osmium, ruthenium can form aqueous cations in its lower oxidation states of +2, unlike the lighter congener iron, ruthenium is paramagnetic at room temperature, as iron also is above its Curie point. The reduction potentials in acidic aqueous solution for some common ruthenium ions are shown below, additionally,34 radioactive isotopes have been discovered. Of these radioisotopes, the most stable are 106Ru with a half-life of 373.59 days, 103Ru with a half-life of 39.26 days, fifteen other radioisotopes have been characterized with atomic weights ranging from 89.93 u to 114.928 u. Most of these have half-lives that are less than five minutes except 95Ru and 105Ru, the primary decay mode before the most abundant isotope, 102Ru, is electron capture and the primary mode after is beta emission. The primary decay product before 102Ru is technetium and the decay product after is rhodium. As the 74th most abundant element in Earths crust, ruthenium is relatively rare and this element is generally found in ores with the other platinum group metals in the Ural Mountains and in North and South America. Small but commercially important quantities are found in pentlandite extracted from Sudbury, Ontario, Canada. The native form of ruthenium is a rare mineral
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Rhodium
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Rhodium is a chemical element with symbol Rh and atomic number 45. It is a rare, silvery-white, hard, and chemically inert transition metal and it is a member of the platinum group. It has only one naturally occurring isotope, 103Rh, naturally occurring rhodium is usually found as the free metal, alloyed with similar metals, and rarely as a chemical compound in minerals such as bowieite and rhodplumsite. It is one of the rarest and most valuable precious metals, Rhodium is a noble metal, resistant to corrosion, found in platinum or nickel ores together with the other members of the platinum group metals. The elements major use is as one of the catalysts in the catalytic converters in automobiles. White gold is often plated with a thin layer to improve its appearance while sterling silver is often rhodium-plated for tarnish resistance. Rhodium detectors are used in nuclear reactors to measure the neutron flux level, Rhodium was discovered in 1803 by William Hyde Wollaston, soon after his discovery of palladium. He used crude platinum ore presumably obtained from South America and his procedure involved dissolving the ore in aqua regia and neutralizing the acid with sodium hydroxide. He then precipitated the platinum as ammonium chloroplatinate by adding ammonium chloride, most other metals like copper, lead, palladium and rhodium were precipitated with zinc. Diluted nitric acid dissolved all but palladium and rhodium, of these, palladium dissolved in aqua regia but rhodium did not, and the rhodium was precipitated by the addition of sodium chloride as Na 3·nH 2O. After being washed with ethanol, the precipitate was reacted with zinc. After the discovery, the element had only minor applications, for example, by the turn of the century. The first major application was electroplating for decorative uses and as corrosion-resistant coating, the introduction of the three-way catalytic converter by Volvo in 1976 increased the demand for rhodium. The previous catalytic converters used platinum or palladium, while the catalytic converter used rhodium to reduce the amount of NOx in the exhaust. Rhodium is a hard, silvery, durable metal that has a high reflectance, Rhodium metal does not normally form an oxide, even when heated. Oxygen is absorbed from the only at the melting point of rhodium. Rhodium has both a melting point and lower density than platinum. It is not attacked by most acids, it is insoluble in nitric acid
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Palladium
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Palladium is a chemical element with symbol Pd and atomic number 46. It is a rare and lustrous silvery-white metal discovered in 1803 by William Hyde Wollaston and he named it after the asteroid Pallas, which was itself named after the epithet of the Greek goddess Athena, acquired by her when she slew Pallas. Palladium, platinum, rhodium, ruthenium, iridium and osmium form a group of elements referred to as the platinum group metals and these have similar chemical properties, but palladium has the lowest melting point and is the least dense of them. More than half the supply of palladium and its congener platinum is used in catalytic converters, Palladium is also used in electronics, dentistry, medicine, hydrogen purification, chemical applications, groundwater treatment, and jewelry. Palladium is a key component of cells, which react hydrogen with oxygen to produce electricity, heat. Ore deposits of palladium and other PGMs are rare, recycling is also a source, mostly from scrapped catalytic converters. The numerous applications and limited supply sources result in considerable investment interest, Palladium belongs to group 10 in the periodic table, but the configuration in the outermost electron shells is atypical for group 10. Fewer electron shells are filled than the directly preceding it. The valence shell has eighteen electrons – ten more than the eight found in the shells of the noble gases from neon onward. Palladium is a soft metal that resembles platinum. It is the least dense and has the lowest melting point of the platinum group metals and it is soft and ductile when annealed and is greatly increased in strength and hardness when cold-worked. Palladium dissolves slowly in concentrated acid, in hot, concentrated sulfuric acid. It dissolves readily at room temperature in aqua regia, common oxidation states of palladium are 0, +1, +2 and +4. Palladium was first observed in 2002, Palladium films with defects produced by alpha particle bombardment at low temperature exhibit superconductivity having Tc=3.2 K. Naturally occurring palladium is composed of seven isotopes, six of which are stable, the most stable radioisotopes are 107Pd with a half-life of 6.5 million years, 103Pd with 17 days, and 100Pd with 3.63 days. Eighteen other radioisotopes have been characterized with atomic weights ranging from 90.94948 u to 122.93426 u and these have half-lives of less than thirty minutes, except 101Pd, 109Pd, and 112Pd. For isotopes with atomic mass unit values less than that of the most abundant stable isotope, 106Pd, the primary mode of decay for those isotopes of Pd with atomic mass greater than 106 is beta decay with the primary product of this decay being silver. Radiogenic 107Ag is a product of 107Pd and was first discovered in 1978 in the Santa Clara meteorite of 1976
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Silver
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Silver is a metallic element with symbol Ag and atomic number 47. The symbol Ag stems from Latin argentum, derived from the Greek ὰργὀς, a soft, white, lustrous transition metal, it exhibits the highest electrical conductivity, thermal conductivity, and reflectivity of any metal. The metal is found in the Earths crust in the pure, free form, as an alloy with gold and other metals. Most silver is produced as a byproduct of copper, gold, lead, Silver is more abundant than gold, but it is much less abundant as a native metal. Its purity is measured on a per mille basis, a 94%-pure alloy is described as 0.940 fine. As one of the seven metals of antiquity, silver has had a role in most human cultures. Silver has long valued as a precious metal. Silver metal is used in many premodern monetary systems in bullion coins, Silver is used in numerous applications other than currency, such as solar panels, water filtration, jewelry, ornaments, high-value tableware and utensils, and as an investment medium. Silver is used industrially in electrical contacts and conductors, in specialized mirrors, window coatings, Silver compounds are used in photographic film and X-rays. Dilute silver nitrate solutions and other compounds are used as disinfectants and microbiocides, added to bandages and wound-dressings, catheters. Silver is similar in its physical and chemical properties to its two neighbours in group 11 of the periodic table, copper and gold. This distinctive electron configuration, with an electron in the highest occupied s subshell over a filled d subshell. Silver is a soft, ductile and malleable transition metal. Silver crystallizes in a cubic lattice with bulk coordination number 12. Unlike metals with incomplete d-shells, metallic bonds in silver are lacking a covalent character and are relatively weak and this observation explains the low hardness and high ductility of single crystals of silver. Silver has a brilliant white metallic luster that can take a polish. Protected silver has greater optical reflectivity than aluminium at all wavelengths longer than ~450 nm, at wavelengths shorter than 450 nm, silvers reflectivity is inferior to that of aluminium and drops to zero near 310 nm. The electrical conductivity of silver is the greatest of all metals, greater even than copper, during World War II in the US,13540 tons of silver were used in electromagnets for enriching uranium, mainly because of the wartime shortage of copper
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Hafnium
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Hafnium is a chemical element with symbol Hf and atomic number 72. A lustrous, silvery gray, tetravalent transition metal, hafnium chemically resembles zirconium and is found in many zirconium minerals and its existence was predicted by Dmitri Mendeleev in 1869, though it was not identified until 1923, making it the penultimate stable element to be discovered. Hafnium is named after Hafnia, the Latin name for Copenhagen, Hafnium is used in filaments and electrodes. Some semiconductor fabrication processes use its oxide for integrated circuits at 45 nm, some superalloys used for special applications contain hafnium in combination with niobium, titanium, or tungsten. Hafnium is a shiny, silvery, ductile metal that is corrosion-resistant, a notable physical difference between these metals is their density, with zirconium having about one-half the density of hafnium. The most notable properties of hafnium are its high thermal neutron-capture cross-section. Hafnium reacts in air to form a film that inhibits further corrosion. The metal is not readily attacked by acids but can be oxidized with halogens or it can be burnt in air, like its sister metal zirconium, finely divided hafnium can ignite spontaneously in air, producing an effect similar to that obtained in Dragons Breath. The metal is resistant to concentrated alkalis, the chemistry of hafnium and zirconium is so similar that the two cannot be separated on the basis of differing chemical reactions. The melting points and boiling points of the compounds and the solubility in solvents are the differences in the chemistry of these twin elements. At least 34 isotopes of hafnium have been observed, ranging in number from 153 to 186. The five stable isotopes are in the range of 176 to 180, the radioactive isotopes half-lives range from only 400 ms for 153Hf, to 2.0 petayears for the most stable one, 174Hf. The nuclear isomer 178m2Hf was at the center of a controversy for several years regarding its use as a weapon. Hafnium is estimated to make up about 5.8 ppm of the Earths upper crust by mass, rarely, the Hf/Zr ratio increases during crystallization to give the isostructural mineral hafnon SiO4, with atomic Hf > Zr. An old name for a variety of zircon containing unusually high Hf content is alvite, a potential source of hafnium is trachyte tuffs containing rare zircon-hafnium silicates eudialyte or armstrongite, at Dubbo in New South Wales, Australia. Hafnium reserves have been estimated to last under 10 years by one source if the world population increases. In reality, since hafnium occurs with zirconium, hafnium can always be a byproduct of extraction to the extent that the low demand requires. The heavy mineral sands ore deposits of the titanium ores ilmenite and rutile yield most of the mined zirconium, zirconium is a good nuclear fuel-rod cladding metal, with the desirable properties of a very low neutron capture cross-section and good chemical stability at high temperatures
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Tantalum
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Tantalum is a chemical element with symbol Ta and atomic number 73. Previously known as tantalium, its name comes from Tantalus, a villain from Greek mythology, tantalum is a rare, hard, blue-gray, lustrous transition metal that is highly corrosion-resistant. It is part of the refractory metals group, which are used as minor components in alloys. The chemical inertness of tantalum makes it a substance for laboratory equipment. Its main use today is in tantalum capacitors in electronic equipment such as phones, DVD players, video game systems. Tantalum, always together with the chemically similar niobium, occurs in the minerals tantalite, columbite, tantalum was discovered in Sweden in 1802 by Anders Ekeberg. One year earlier, Charles Hatchett had discovered the element columbium and he decided to keep the name tantalum. After Friedrich Wöhler confirmed these results, it was thought that columbium and tantalum were the same element. The supposed element pelopium was identified as a mixture of tantalum and niobium. Further confirmation came from the Swiss chemist Jean Charles Galissard de Marignac, in 1866 and these discoveries did not stop scientists from publishing articles about the so-called ilmenium until 1871. De Marignac was the first to produce the form of tantalum in 1864. Early investigators had only been able to produce impure tantalum, wires made with metallic tantalum were used for light bulb filaments until tungsten replaced it in widespread use. The name tantalum was derived from the name of the mythological Tantalus, in the story, he had been punished after death by being condemned to stand knee-deep in water with perfect fruit growing above his head, both of which eternally tantalized him. Ekeberg wrote This metal I call tantalum, partly in allusion to its incapacity, when immersed in acid, to absorb any and be saturated. This method has been supplanted by solvent extraction from fluoride-containing solutions of tantalum, tantalum is dark, dense, ductile, very hard, easily fabricated, and highly conductive of heat and electricity. The metal is renowned for its resistance to corrosion by acids, in fact and it can be dissolved with hydrofluoric acid or acidic solutions containing the fluoride ion and sulfur trioxide, as well as with a solution of potassium hydroxide. Tantalums high melting point of 3017 °C is exceeded among the only by tungsten, rhenium and osmium for metals. Tantalum exists in two phases, alpha and beta
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Tungsten
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Tungsten, also known as wolfram, is a chemical element with symbol W and atomic number 74. The word tungsten comes from the Swedish language tung sten, which translates to heavy stone. Its name in Swedish is volfram, however, in order to distinguish it from scheelite, a hard, rare metal under standard conditions when uncombined, tungsten is found naturally on Earth almost exclusively in chemical compounds. It was identified as a new element in 1781, and first isolated as a metal in 1783 and its important ores include wolframite and scheelite. The free element is remarkable for its robustness, especially the fact that it has the highest melting point of all the elements discovered, melting at 3,422 °C,6,192 °F. Its high density is 19.3 times that of water, comparable to that of uranium and gold, polycrystalline tungsten is an intrinsically brittle and hard material, making it difficult to work. However, pure single-crystalline tungsten is more ductile, and can be cut with a hard-steel hacksaw, tungstens many alloys have numerous applications, including incandescent light bulb filaments, X-ray tubes, electrodes in TIG welding, superalloys, and radiation shielding. Tungstens hardness and high density give it military applications in penetrating projectiles, tungsten compounds are also often used as industrial catalysts. Tungsten is the metal from the third transition series that is known to occur in biomolecules. It is the heaviest element known to be essential to any living organism, tungsten interferes with molybdenum and copper metabolism and is somewhat toxic to animal life. In its raw form, tungsten is a hard metal that is often brittle. If made very pure, tungsten retains its hardness, and becomes malleable enough that it can be worked easily and it is worked by forging, drawing, or extruding. Tungsten objects are commonly formed by sintering. Of all metals in pure form, tungsten has the highest melting point, lowest vapor pressure, although carbon remains solid at higher temperatures than tungsten, carbon sublimes, rather than melts, so tungsten is considered to have a higher melting point. Tungsten has the lowest coefficient of expansion of any pure metal. The low thermal expansion and high melting point and tensile strength of tungsten originate from strong covalent bonds formed between tungsten atoms by the 5d electrons, alloying small quantities of tungsten with steel greatly increases its toughness. Tungsten exists in two crystalline forms, α and β. The former has a cubic structure and is the more stable form
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Rhenium
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Rhenium is a chemical element with symbol Re and atomic number 75. It is a silvery-white, heavy, third-row transition metal in group 7 of the periodic table, with an estimated average concentration of 1 part per billion, rhenium is one of the rarest elements in the Earths crust. Rhenium shows in its compounds a variety of oxidation states ranging from −1 to +7. Discovered in 1925, rhenium was the last stable element to be discovered and it was named after the river Rhine in Europe. Nickel-based superalloys of rhenium are used in the chambers, turbine blades. These alloys contain up to 6% rhenium, making jet engine construction the largest single use for the element, rhenium was the last-discovered of the elements that have a stable isotope. The existence of an element at this position in the periodic table had been first predicted by Dmitri Mendeleev. Other calculated information was obtained by Henry Moseley in 1914 and it is generally considered to have been discovered by Walter Noddack, Ida Tacke, and Otto Berg in Germany. In 1925 they reported that they had detected the element in platinum ore and they also found rhenium in gadolinite and molybdenite. In 1928 they were able to extract 1 g of the element by processing 660 kg of molybdenite and it was estimated in 1968 that 75% of the rhenium metal in the United States was used for research and the development of refractory metal alloys. It took several years from that point before the superalloys became widely used, in 1908, Japanese chemist Masataka Ogawa announced that he had discovered the 43rd element and named it nipponium after Japan. However, recent analysis indicated the presence of rhenium, not element 43, the symbol Np was later used for the element neptunium, and the name nihonium, also named after Japan, along with symbol Nh, represents element 113. Rhenium is a metal with one of the highest melting points of all elements, exceeded by only tungsten. It also has one of the highest boiling point of all elements and it is also one of the densest, exceeded only by platinum, iridium and osmium. Rhenium has a hexagonal close-packed crystal structure, with parameters a =276.1 pm. Its usual commercial form is a powder, but this element can be consolidated by pressing and sintering in a vacuum or hydrogen atmosphere and this procedure yields a compact solid having a density above 90% of the density of the metal. When annealed this metal is very ductile and can be bent, coiled, rhenium-molybdenum alloys are superconductive at 10 K, tungsten-rhenium alloys are also superconductive around 4–8 K, depending on the alloy. Rhenium metal superconducts at 1.697 ±0.006 K, in bulk form and at room temperature and atmospheric pressure, the element resists alkalis, sulfuric acid, hydrochloric acid, dilute nitric acid, and aqua regia
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Osmium
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Osmium is a chemical element with symbol Os and atomic number 76. It is a hard, brittle, bluish-white transition metal in the group that is found as a trace element in alloys. Osmium is the densest naturally occurring element, with a density of 22.59 g/cm3, Osmium has a blue-gray tint and is the densest stable element, approximately twice the density of lead and slightly denser than iridium. Calculations of density from the X-ray diffraction data may produce the most reliable data for these elements, Osmium is a hard but brittle metal that remains lustrous even at high temperatures. It has a very low compressibility, correspondingly, its bulk modulus is extremely high, reported between 395 and 462 GPa, which rivals that of diamond. The hardness of osmium is moderately high at 4 GPa, because of its hardness, brittleness, low vapor pressure, and very high melting point, solid osmium is difficult to machine, form, or work. Osmium forms compounds with oxidation states ranging from −2 to +8, the most common oxidation states are +2, +3, +4, and +8. The +8 oxidation state is notable for being the highest attained by any chemical element aside from iridiums +9 and is encountered only in xenon, ruthenium, hassium, and iridium. The oxidation states −1 and −2 represented by the two reactive compounds Na 2 and Na 2 are used in the synthesis of osmium cluster compounds, the most common compound exhibiting the +8 oxidation state is osmium tetroxide. This toxic compound is formed when powdered osmium is exposed to air and it is a very volatile, water-soluble, pale yellow, crystalline solid with a strong smell. Osmium powder has the smell of osmium tetroxide. Osmium tetroxide forms red osmates OsO 42−2 upon reaction with a base, with ammonia, it forms the nitrido-osmates OsO 3N−. Osmium tetroxide boils at 130 °C and is an oxidizing agent. By contrast, osmium dioxide is black, non-volatile, and much less reactive, Osmium pentafluoride is known, but osmium trifluoride has not yet been synthesized. The lower oxidation states are stabilized by the halogens, so that the trichloride, tribromide, triiodide. The oxidation state +1 is known only for osmium iodide, whereas several carbonyl complexes of osmium, such as triosmium dodecacarbonyl, in general, the lower oxidation states of osmium are stabilized by ligands that are good σ-donors and π-acceptors. The higher oxidation states are stabilized by strong σ- and π-donors, such as O2−, despite its broad range of compounds in numerous oxidation states, osmium in bulk form at ordinary temperatures and pressures resists attack by all acids and alkalis, including aqua regia. Osmium has seven naturally occurring isotopes, six of which are stable, 184Os, 187Os, 188Os, 189Os, 190Os, and 192Os
39.
Iridium
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Iridium is a chemical element with symbol Ir and atomic number 77. A very hard, brittle, silvery-white transition metal of the platinum group and it is also the most corrosion-resistant metal, even at temperatures as high as 2000 °C. Although only certain molten salts and halogens are corrosive to solid iridium, finely divided iridium dust is more reactive. Iridium was discovered in 1803 among insoluble impurities in natural platinum, Smithson Tennant, the primary discoverer, named iridium for the Greek goddess Iris, personification of the rainbow, because of the striking and diverse colors of its salts. Iridium is one of the rarest elements in Earths crust, with production and consumption of only three tonnes. 191Ir and 193Ir are the two naturally occurring isotopes of iridium, as well as the only stable isotopes, the latter is the more abundant of the two. Iridium radioisotopes are used in some radioisotope thermoelectric generators, Iridium is found in meteorites in much higher abundance than in the Earths crust. Similarly, an anomaly in core samples from the Pacific Ocean suggested the Eltanin impact of about 2.5 million years ago. A member of the platinum metals, iridium is white, resembling platinum. Because of its hardness, brittleness, and very high melting point, solid iridium is difficult to machine, form, or work, thus powder metallurgy is commonly employed and it is the only metal to maintain good mechanical properties in air at temperatures above 1,600 °C. The measured density of iridium is only lower than that of osmium. Iridium is the most corrosion-resistant metal known, it is not attacked by almost any acid, aqua regia, molten metals, or silicates at high temperatures. It can, however, be attacked by some molten salts, such as cyanide and potassium cyanide, as well as oxygen. Iridium forms compounds in oxidation states between −3 and +9, the most common oxidation states are +3 and +4, well-characterized examples of the high +6 oxidation state are rare, but include IrF6 and two mixed oxides Sr 2MgIrO6 and Sr 2CaIrO6. In addition, it was reported in 2009 that iridium oxide was prepared under matrix isolation conditions by UV irradiation of an iridium-peroxo complex and this species, however, is not expected to be stable as a bulk solid at higher temperatures. The highest oxidation state, which is also the highest recorded for any element, is known in one cation, IrO+4. Iridium dioxide, IrO2, a powder, is the only well-characterized oxide of iridium. A sesquioxide, Ir 2O3, has described as a blue-black powder which is oxidized to IrO2 by HNO3
40.
Platinum
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Platinum is a chemical element with symbol Pt and atomic number 78. It is a dense, malleable, ductile, highly unreactive, precious and its name is derived from the Spanish term platina, translated into little silver. Platinum is a member of the group of elements and group 10 of the periodic table of elements. It has six naturally occurring isotopes and it is one of the rarer elements in Earths crust with an average abundance of approximately 5 μg/kg. It occurs in some nickel and copper ores along with some deposits, mostly in South Africa. Because of its scarcity in Earths crust, only a few hundred tonnes are produced annually, Platinum is one of the least reactive metals. It has remarkable resistance to corrosion, even at high temperatures, consequently, platinum is often found chemically uncombined as native platinum. Because it occurs naturally in the sands of various rivers. Platinum is used in catalytic converters, laboratory equipment, electrical contacts and electrodes, platinum resistance thermometers, dentistry equipment, and jewelry. Being a heavy metal, it leads to health issues upon exposure to its salts, compounds containing platinum, such as cisplatin, oxaliplatin and carboplatin, are applied in chemotherapy against certain types of cancer. Pure platinum is a lustrous, ductile, and malleable, silver-white metal, Platinum is more ductile than gold, silver or copper, thus being the most ductile of pure metals, but it is less malleable than gold. The metal has excellent resistance to corrosion, is stable at temperatures and has stable electrical properties. Platinum reacts with oxygen slowly at high temperatures. It reacts vigorously with fluorine at 500 °C to form platinum tetrafluoride and it is also attacked by chlorine, bromine, iodine, and sulfur. Platinum is insoluble in hydrochloric and nitric acid, but dissolves in hot aqua regia to form chloroplatinic acid and its physical characteristics and chemical stability make it useful for industrial applications. Its resistance to wear and tarnish is well suited to use in fine jewelry, the most common oxidation states of platinum are +2 and +4. The +1 and +3 oxidation states are common, and are often stabilized by metal bonding in bimetallic species. As is expected, tetracoordinate platinum compounds tend to adopt 16-electron square planar geometries, Platinum has six naturally occurring isotopes, 190Pt, 192Pt, 194Pt, 195Pt, 196Pt, and 198Pt
41.
Gold
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Gold is a chemical element with symbol Au and atomic number 79. In its purest form, it is a bright, slightly yellow, dense, soft, malleable. Chemically, gold is a metal and a group 11 element. It is one of the least reactive chemical elements and is solid under standard conditions, Gold often occurs in free elemental form, as nuggets or grains, in rocks, in veins, and in alluvial deposits. It occurs in a solid solution series with the element silver and also naturally alloyed with copper. Less commonly, it occurs in minerals as gold compounds, often with tellurium, golds atomic number of 79 makes it one of the higher numbered, naturally occurring elements. It is thought to have produced in supernova nucleosynthesis, from the collision of neutron stars. Because the Earth was molten when it was formed, almost all of the present in the early Earth probably sank into the planetary core. Gold is resistant to most acids, though it does dissolve in aqua regia, a mixture of acid and hydrochloric acid. Gold also dissolves in solutions of cyanide, which are used in mining and electroplating. Gold dissolves in mercury, forming amalgam alloys, but this is not a chemical reaction, as a precious metal, gold has been used for coinage, jewelry, and other arts throughout recorded history. A total of 186,700 tonnes of gold is in existence above ground, the world consumption of new gold produced is about 50% in jewelry, 40% in investments, and 10% in industry. Gold is also used in infrared shielding, colored-glass production, gold leafing, certain gold salts are still used as anti-inflammatories in medicine. As of 2014, the worlds largest gold producer by far was China with 450 tonnes, Gold is cognate with similar words in many Germanic languages, deriving via Proto-Germanic *gulþą from Proto-Indo-European *ǵʰelh₃-. The symbol Au is from the Latin, aurum, the Latin word for gold, the Proto-Indo-European ancestor of aurum was *h₂é-h₂us-o-, meaning glow. This word is derived from the root as *h₂éu̯sōs, the ancestor of the Latin word Aurora. This etymological relationship is presumably behind the frequent claim in scientific publications that aurum meant shining dawn, Gold is the most malleable of all metals, a single gram can be beaten into a sheet of 1 square meter, and an avoirdupois ounce into 300 square feet. Gold leaf can be thin enough to become semi-transparent
42.
Rutherfordium
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Rutherfordium is a chemical element with symbol Rf and atomic number 104, named in honor of physicist Ernest Rutherford. It is an element and radioactive, the most stable known isotope. In the periodic table of the elements, it is a d-block element and it is a member of the 7th period and belongs to the group 4 elements. Chemistry experiments have confirmed that rutherfordium behaves as the homologue to hafnium in group 4. The chemical properties of rutherfordium are characterized only partly, in the 1960s, small amounts of rutherfordium were produced in the Joint Institute for Nuclear Research in the former Soviet Union and at Lawrence Berkeley National Laboratory in California. Rutherfordium was reportedly first detected in 1964 at the Joint Institute of Nuclear Research at Dubna, researchers there bombarded a plutonium-242 target with neon-22 ions and separated the reaction products by gradient thermochromatography after conversion to chlorides by interaction with ZrCl4. The team identified spontaneous fission activity contained within a volatile chloride portraying eka-hafnium properties, the Russian scientists proposed the name kurchatovium and the American scientists suggested the name rutherfordium for the new element. The American group wrote a response to the findings of the TWG. In particular they pointed out that the Russian group had altered the details of their claims several times over a period of 20 years, the IUPAC finally used the name suggested by the American team which may in some way reflect a change of opinion. As a consequence of the competing claims of discovery, an element naming controversy arose. Since the Soviets claimed to have first detected the new element they suggested the name kurchatovium in honor of Igor Kurchatov and this name had been used in books of the Soviet Bloc as the official name of the element. The Americans, however, proposed rutherfordium for the new element to honor Ernest Rutherford, the International Union of Pure and Applied Chemistry adopted unnilquadium as a temporary, systematic element name, derived from the Latin names for digits 1,0, and 4. In 1994, IUPAC suggested the name dubnium to be used since rutherfordium was suggested for element 106, however, there was still a dispute over the names of elements 104–107. In 1997 the teams involved resolved the dispute and adopted the current name rutherfordium, the name dubnium was given to element 105 at the same time. Rutherfordium has no stable or naturally occurring isotopes, several radioactive isotopes have been synthesized in the laboratory, either by fusing two atoms or by observing the decay of heavier elements. Sixteen different isotopes have been reported with atomic masses from 253 to 270, most of these decay predominantly through spontaneous fission pathways. Out of isotopes whose half-lives are known, the lighter isotopes usually have shorter half-lives, half-lives of under 50 μs for 253Rf and 254Rf were observed, the heaviest isotopes are the most stable, with 267Rf having a measured half-life of about 1.3 h. Half-lives for 269Rf, 271Rf, and higher are not known and have not yet been predicted, the lightest isotopes were synthesized by direct fusion between two lighter nuclei and as decay products
43.
Dubnium
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Dubnium is a chemical element with symbol Db and atomic number 105. A transactinide element, dubnium is highly radioactive, the most stable known isotope and this greatly limits the extent of possible research on dubnium. Dubnium does not occur naturally on Earth and is produced artificially, the first discovery of the element was claimed by the Soviet Joint Institute for Nuclear Research in 1968, followed in 1970 by the American University of California. Both teams proposed a name for the new element, and used it without formal approval, the long-standing dispute was resolved in 1997, when the element was officially named dubnium after Dubna, the site of the JINR. In the periodic table of the elements, dubnium is located in period 7, in d-block, Dubnium belongs to group 5 as the third member of the 6d series of transition metals. In the coming years, the American team undoubtedly synthesized the following elements up to mendelevium, however, in 1956, the Joint Institute for Nuclear Research in Dubna, Moscow Oblast, Russian SFSR, Soviet Union, was founded and became a major rival to the American team. The first report of discovery of element 105 came from the JINR in 1968, a target of americium-243 was bombarded by a beam of neon-22 ions. The scientists at Dubna reported 9.4 MeV and 9.7 MeV alpha activities followed by alpha activities similar to those of lawrencium-256, in February 1970, a following paper was published. Two activities were found, with half-lives of 14 ms and 2. 2±0.5 s, the former activity was assigned to 242mfAm, the latter one was described as having been caused by an isotope of element 105. A subsequent paper, released in May 1970, reported that this isotope was probably 261105, in April 1970, a team led by Albert Ghiorso working at the University of California stepped into the competition. They claimed to have synthesized the element by bombarding a target with nitrogen-15 ions. In May 1970, the first paper discussing chemical examination and confirmation of the supposed element 105 was published in Dubna and that work relied on the previous data from Dubna, the February 1970 paper. The team identified a 2. 2-second spontaneous fission activity contained within a volatile chloride portraying eka-tantalum properties, in June 1970, the Dubna team made improvements on their original experiment, providing a purer target and intensity of transfer reactions reduced by using a collimator before the catcher. This time, they were able to find 9.1 MeV alpha activities with daughter isotopes identifiable as either 256Lr or 257Lr, thus, the original isotope was either 260105 or 261105. The Soviet team proposed the name nielsbohrium in honor of the Danish nuclear physicist Niels Bohr, one of the founders of the theories of the atomic structure and the quantum theory. The American team proposed that the new element should be named hahnium, in honor of the German chemist Otto Hahn, however, tensions in the late 1960s and 1970s simmered down somewhat. Both teams synthesized the element, element 106, but decided not to suggest their names. In 1968, the Soviet team presented a report calling recognition of discovery of elements 102 and 103 by other teams hasty, afterwards, they suggested establishing an international committee on elaborating the discovery criteria
44.
Seaborgium
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Seaborgium is a chemical element with symbol Sg and atomic number 106. It is named after the American nuclear chemist Glenn T. Seaborg and it is a synthetic element and radioactive, the most stable known isotope, 269Sg, has a half-life of approximately 3.1 minutes. In the periodic table of the elements, it is a transactinide element. It is a member of the 7th period and belongs to the group 6 elements as the member of the 6d series of transition metals. Chemistry experiments have confirmed that seaborgium behaves as the homologue to tungsten in group 6. The chemical properties of seaborgium are characterized only partly, but they compare well with the chemistry of the other group 6 elements, in 1974, a few atoms of seaborgium were produced in laboratories in the former Soviet Union and in the United States. It is one of two elements named after a living person at the time of naming, the other being oganesson. Two groups claimed discovery of the element, in total, fifty-one spontaneous fission events were observed with a half-life between four and ten milliseconds. The isotope in question was first suggested to be seaborgium-259, but was corrected to seaborgium-260. 208 82Pb +54 24Cr →260 106Sg +2 n 207 82Pb +54 24Cr →260 106Sg + n A few months later in 1974, researchers at the University of California, Berkeley, including Glenn T. 9±0.2 seconds. The cross-section of the observed,0.3 nanobarns. These bolstered the assignment of the decay events to seaborgium-263m. As such, the TWG recognised the Berkeley team as discoverers in their 1993 report. However, due to the relations between the competing teams after the publication of the TWG report, this proposal was dropped from consideration by the Berkeley team. However, IUPAC resolved in August 1994 that an element could not be named after a living person, at first, IUPAC defended itself, with an American member of its committee writing, Discoverers dont have a right to name an element. They have a right to suggest a name, and, of course, we didnt infringe on that at all. This list was finally accepted by the American Chemical Society, which wrote, Seaborg commented regarding the naming, Seaborg died a year, super-heavy elements such as seaborgium are produced by bombarding lighter elements in particle accelerators that induces fusion reactions. Whereas most of the isotopes of seaborgium can be synthesized directly this way, depending on the energies involved, the former are separated into hot and cold
45.
Bohrium
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Bohrium is a chemical element with symbol Bh and atomic number 107. It is named after Danish physicist Niels Bohr, in the periodic table of the elements, it is a d-block transactinide element. It is a member of the 7th period and belongs to the group 7 elements as the member of the 6d series of transition metals. Chemistry experiments have confirmed that bohrium behaves as the homologue to rhenium in group 7. The chemical properties of bohrium are characterized only partly, but they compare well with the chemistry of the other group 7 elements, two groups claimed discovery of the element. Two activities, one with a half-life of one to two milliseconds, and the other with an approximately five-second half-life, were seen. The IUPAC/IUPAP Transfermium Working Group concluded that while dubnium-258 was probably seen in this experiment, the IUPAC/IUPAP Transfermium Working Group recognised the GSI collaboration as official discoverers in their 1992 report. The German group suggested the name nielsbohrium with symbol Ns to honor the Danish physicist Niels Bohr, the Dubna team agreed with the German groups naming proposal for element 107. There was an element naming controversy as to what the elements from 104 to 106 were to be called, the IUPAC adopted unnilseptium as a temporary, systematic element name for this element. In 1994 a committee of IUPAC recommended that element 107 be named bohrium, not nielsbohrium, since there was no precedence for using a scientists complete name in the naming of an element. The matter was handed to the Danish branch of IUPAC which, despite this, voted in favour of the name bohrium, Bohrium has no stable or naturally occurring isotopes. Several radioactive isotopes have been synthesized in the laboratory, either by fusing two atoms or by observing the decay of heavier elements. Twelve different isotopes of bohrium have been reported with atomic masses 260–262, 264–267, 270–272,274, all of these but the unconfirmed 278Bh decay only through alpha decay, although some unknown bohrium isotopes are predicted to undergo spontaneous fission. The lighter isotopes usually have shorter half-lives, half-lives of under 100 ms for 260Bh, 261Bh, 262Bh, 264Bh, 265Bh, 266Bh, and 271Bh are more stable at around 1 s, and 267Bh and 272Bh have half-lives of about 10 s. The unknown isotopes 273Bh and 275Bh are predicted to have even longer half-lives of around 90 minutes and 40 minutes respectively. Before its discovery, 274Bh was also predicted to have a long half-life of 90 minutes, the five most neutron-rich ones with masses 270,271,272,274, and 278 appear in the decay chains of 282Nh, 287Mc, 288Mc, 294Ts, and 290Fl respectively. These eleven isotopes have half-lives ranging from ten milliseconds for 262mBh to about one minute for 270Bh and 274Bh. Bohrium is the member of the 6d series of transition metals
46.
Hassium
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Hassium is a chemical element with symbol Hs and atomic number 108, named after the German state of Hesse. It is an element and radioactive, the most stable known isotope. More than 100 atoms of hassium have been synthesized to date, in the periodic table of the elements, it is a d-block transactinide element. It is a member of the 7th period and belongs to the group 8 elements, Chemistry experiments have confirmed that hassium behaves as the heavier homologue to osmium in group 8. The chemical properties of hassium are characterized only partly, but they compare well with the chemistry of the other group 8 elements, in bulk quantities, hassium is expected to be a silvery metal that reacts readily with oxygen in the air, forming a volatile tetroxide. Hassium was officially discovered in 1984 by a German research team led by Peter Armbruster, the team bombarded a target of lead-208 with accelerated nuclei of iron-58 to produce 3 atoms of the isotope hassium-265. Due to this issue, a controversy arose over who should be recognized as the discoverer of the element. The IUPAC/IUPAP Transfermium Working Group recognised the GSI collaboration as official discoverers in their 1992 report and this statement came in spite of the combined data also supporting the Russian 1983 discovery claim and the TWG also acknowledging that very probably element 108 played a role in the Dubna experiment. Using Mendeleevs nomenclature for unnamed and undiscovered elements, hassium should be known as eka-osmium and this was because they felt that Hesse did not merit an element being named after it. After protests from the German discoverers and the American Chemical Society, IUPAC relented, Hassium is not known to occur naturally on Earth, the half-lives of all its known isotopes are short enough that no primordial hassium would have survived to the present day. This does not rule out the possibility of unknown longer-lived isotopes or nuclear isomers existing, in the early 1960s, it was predicted that long-lived deformed isomers of hassium might occur naturally on Earth in trace quantities. His rationale for claiming that sergenium was the heavier homologue to osmium was that minerals supposedly containing sergenium formed volatile oxides when boiled in nitric acid, similarly to osmium. His findings were criticized by V. M. Kulakov on the grounds some of the properties Cherdyntsev claimed sergenium had were inconsistent with the then-current nuclear physics. In 2003 it was suggested that the alpha decay with energy 4. In 2004, the Joint Institute for Nuclear Research conducted a search for natural hassium and this was done underground to avoid interference and false positives from cosmic rays, but no results have been released, strongly implying that no natural hassium was found. The possible extent of primordial hassium on Earth is uncertain, it now only exist in traces. Since hassium is homologous to osmium, it should occur along with osmium in osmiridium if it occurred in nature. The decay chains of 271Bh and 271Sg are very hypothetical and the predicted half-life of this hypothetical hassium isomer is not long enough for any sufficient quantity to remain on Earth
47.
Post-transition metal
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In chemistry, post-transition metals are the metallic elements in the periodic table located between the transition metals and the metalloids. Usually included in this category are gallium, indium and thallium, tin and lead, which elements are counted as post-transition metals depends, in periodic table terms, on where the transition metals are taken to end and where the metalloids or non-metals are taken to start. Physically, post-transition metals are soft, have poor mechanical strength, chemically, they are characterised—to varying degrees—by covalent bonding tendencies, acid-base amphoterism and the formation of anionic species such as aluminates, stannates, and bismuthates. They can also form Zintl phases, the expression post-transition metals is used here as there is no IUPAC-approved collective name for these metals. Occasionally, some or all of them have instead been referred to as B-subgroup metals, other metals, or p-block metals, all these labels are surveyed later in this article. Usually included in this category are the group 13–15 metals, gallium, indium and thallium, tin and lead, other elements sometimes included are copper, silver and gold, zinc, cadmium and mercury, and aluminium, germanium, arsenic and antimony. Astatine, which is classified as a nonmetal or a metalloid, has been predicted to have a metallic crystalline structure. If so, it would be a post-transition metal, elements 112–117 may be post-transition metals, insufficient quantities of them have been synthesized to allow investigation of their actual physical and chemical properties. Which elements start to be counted as post-transition metals depends, in periodic table terms, in the 1950s, most inorganic chemistry textbooks defined transition elements as finishing at group 10, therefore excluding group 11, and group 12. A survey of books in 2003 showed that the transition metals ended at either group 11 or group 12 with roughly equal frequency. Where the post-transition metals end depends on where the metalloids or nonmetals start, boron, silicon, germanium, arsenic, antimony and tellurium are commonly recognised as metalloids, other authors treat some or all of these elements as nonmetals. The diminished metallic nature of the metals is largely attributable to the increase in nuclear charge going across the periodic table. With some irregularities, atomic radii contract, ionisation energies increase, fewer electrons become available for metallic bonding, the reductions in atomic size due to the interjection of the d- and f-blocks are referred to as, respectively, the scandide or d-block contraction, and the lanthanide contraction. Relativistic effects also increase the energy, and hence ionisation energy, of the electrons in the 6s shell in gold and mercury. The origin of the term post-transition metal is unclear, an early usage is recorded by Deming, in 1940, in his well-known book Fundamental Chemistry. He treated the transition metals as finishing at group 10 and he referred to the ensuing elements in periods 4 to 6 of the periodic table —in view of their underlying d10 electronic configurations—as post-transition metals. This section outlines relevant physical and chemical properties of the elements typically or sometimes classified as post-transition metals, for complete profiles, including history, production, specific uses, and biological roles and precautions, see the main article for each element. Abbreviations, MH—Mohs hardness, BCN—bulk coordination number, the group 11 metals are typically categorised as transition metals given they can form ions with incomplete d-shells
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Aluminium
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Aluminium or aluminum is a chemical element in the boron group with symbol Al and atomic number 13. It is a silvery-white, soft, nonmagnetic, ductile metal, Aluminium metal is so chemically reactive that native specimens are rare and limited to extreme reducing environments. Instead, it is combined in over 270 different minerals. The chief ore of aluminium is bauxite, Aluminium is remarkable for the metals low density and its ability to resist corrosion through the phenomenon of passivation. Aluminium and its alloys are vital to the industry and important in transportation and structures, such as building facades. The oxides and sulfates are the most useful compounds of aluminium, despite its prevalence in the environment, no known form of life uses aluminium salts metabolically, but aluminium is well tolerated by plants and animals. Because of these salts abundance, the potential for a role for them is of continuing interest. Aluminium is a soft, durable, lightweight, ductile. It is nonmagnetic and does not easily ignite, a fresh film of aluminium serves as a good reflector of visible light and an excellent reflector of medium and far infrared radiation. The yield strength of aluminium is 7–11 MPa, while aluminium alloys have yield strengths ranging from 200 MPa to 600 MPa. Aluminium has about one-third the density and stiffness of steel and it is easily machined, cast, drawn and extruded. Aluminium atoms are arranged in a cubic structure. Aluminium has an energy of approximately 200 mJ/m2. Aluminium is a thermal and electrical conductor, having 59% the conductivity of copper. Aluminium is capable of superconductivity, with a critical temperature of 1.2 kelvin. Aluminium is the most common material for the fabrication of superconducting qubits, the strongest aluminium alloys are less corrosion resistant due to galvanic reactions with alloyed copper. This corrosion resistance is reduced by aqueous salts, particularly in the presence of dissimilar metals. In highly acidic solutions, aluminium reacts with water to form hydrogen, primarily because it is corroded by dissolved chlorides, such as common sodium chloride, household plumbing is never made from aluminium
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Zinc
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Zinc is a chemical element with the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table, in some respects zinc is chemically similar to magnesium, both elements exhibit only one normal oxidation state, and the Zn2+ and Mg2+ ions are of similar size. Zinc is the 24th most abundant element in Earths crust and has five stable isotopes, the most common zinc ore is sphalerite, a zinc sulfide mineral. The largest workable lodes are in Australia, Asia, and the United States, Zinc is refined by froth flotation of the ore, roasting, and final extraction using electricity. Zinc metal was not produced on a large scale until the 12th century in India and was unknown to Europe until the end of the 16th century, the mines of Rajasthan have given definite evidence of zinc production going back to the 6th century BC. To date, the oldest evidence of pure zinc comes from Zawar, in Rajasthan, alchemists burned zinc in air to form what they called philosophers wool or white snow. The element was named by the alchemist Paracelsus after the German word Zinke. German chemist Andreas Sigismund Marggraf is credited with discovering pure metallic zinc in 1746, work by Luigi Galvani and Alessandro Volta uncovered the electrochemical properties of zinc by 1800. Corrosion-resistant zinc plating of iron is the application for zinc. Other applications are in batteries, small non-structural castings. A variety of compounds are commonly used, such as zinc carbonate and zinc gluconate, zinc chloride, zinc pyrithione, zinc sulfide. Zinc is an essential mineral perceived by the public today as being of exceptional biologic and public health importance, Zinc deficiency affects about two billion people in the developing world and is associated with many diseases. In children, deficiency causes growth retardation, delayed sexual maturation, infection susceptibility, enzymes with a zinc atom in the reactive center are widespread in biochemistry, such as alcohol dehydrogenase in humans. Consumption of excess zinc can cause ataxia, lethargy and copper deficiency, Zinc is a bluish-white, lustrous, diamagnetic metal, though most common commercial grades of the metal have a dull finish.6 pm. The metal is hard and brittle at most temperatures but becomes malleable between 100 and 150 °C, above 210 °C, the metal becomes brittle again and can be pulverized by beating. Zinc is a conductor of electricity. For a metal, zinc has relatively low melting and boiling points, the melting point is the lowest of all the transition metals aside from mercury and cadmium. Many alloys contain zinc, including brass, Other metals long known to form binary alloys with zinc are aluminium, antimony, bismuth, gold, iron, lead, mercury, silver, tin, magnesium, cobalt, nickel, tellurium, and sodium
The dictionary definition of metal at Wiktionary
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