1.
Periodic table
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The periodic table is a tabular arrangement of the chemical elements, ordered by their atomic number, electron configurations, and recurring chemical properties. This ordering shows periodic trends, such as elements with similar behaviour in the same column and it also shows four rectangular blocks with some approximately similar chemical properties. In general, within one row the elements are metals on the left, the rows of the table are called periods, the columns are called groups. Six groups have names as well as numbers, for example, group 17 elements are the halogens, and group 18, the noble gases. The periodic table can be used to derive relationships between the properties of the elements, and predict the properties of new elements yet to be discovered or synthesized, the periodic table provides a useful framework for analyzing chemical behaviour, and is widely used in chemistry and other sciences. The Russian chemist Dmitri Mendeleev published the first widely recognized periodic table in 1869 and he developed his table to illustrate periodic trends in the properties of the then-known elements. Mendeleev also predicted some properties of elements that would be expected to fill gaps in this table. Most of his predictions were proved correct when the elements in question were subsequently discovered, Mendeleevs periodic table has since been expanded and refined with the discovery or synthesis of further new elements and the development of new theoretical models to explain chemical behaviour. The first 94 elements exist naturally, although some are only in trace amounts and were synthesized in laboratories before being found in nature. Elements with atomic numbers from 95 to 118 have only been synthesized in laboratories or nuclear reactors, synthesis of elements having higher atomic numbers is being pursued. Numerous synthetic radionuclides of naturally occurring elements have also produced in laboratories. Each chemical element has an atomic number representing the number of protons in its nucleus. Most elements have differing numbers of neutrons among different atoms, with variants being referred to as isotopes. Isotopes are never separated in the table, they are always grouped together under a single element. Elements with no stable isotopes have the masses of their most stable isotopes. In the standard periodic table, the elements are listed in order of increasing atomic number, a new row is started when a new electron shell has its first electron. Columns are determined by the configuration of the atom, elements with the same number of electrons in a particular subshell fall into the same columns. Thus, it is easy to predict the chemical properties of an element if one knows the properties of the elements around it
2.
Alternative periodic tables
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Alternative periodic tables are tabulations of chemical elements differing significantly in their organization from the traditional depiction of the periodic system. Several have been devised, often purely for reasons, as not all correlations between the chemical elements are effectively captured by the standard periodic table. Alternative periodic tables are developed often to highlight or emphasize different chemical or physical properties of the elements which are not as apparent in traditional periodic tables, some tables aim to emphasize both the nucleon and electronic structure of atoms. This can be done by changing the relationship or representation each element has with respect to another element in the table. Other tables aim to emphasize the chemical element isolations by humans over time, charles Janets Left step periodic table is considered to be the most significant alternative to the traditional depiction of the periodic system. It organizes elements according to orbital filling and is used by physicists. For example, most of the row in the standard table is the fifth row in this table. A modern version of the table is constructed by Valery Tsimmerman. Its structure is based on the four numbers of the electron configuration. A superactinide island is already slotted in, the Chemical Galaxy is organized in a similar way. Timothy Stowes physicists periodic table is three-dimensional with the three representing the principal quantum number, orbital quantum number, and orbital magnetic quantum number. Helium is again a group 2 element, paul Giguères 3-D periodic table consists of 4 connected billboards with the elements written on the front and the back. The first billboard has the group 1 elements on the front, at a 90° angle the second billboard contains the groups 13 to 18 front and back. Two more billboard each making 90° angles contain the other elements, rich has proposed a periodic table where elements appear more than once when appropriate. In this rendition of the periodic table carbon and silicon also appear in the group as titanium and zirconium. A chemists table with a positioning of hydrogen, helium. From Mendeleevs original periodic table, elements have been arranged by valence. Over the years and with discoveries in atomic structure, this schema has been adjusted and expanded, the oldest periodic table is the short form table by Dmitri Mendeleev, which shows secondary chemical kinships
3.
History of the periodic table
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The periodic table is an arrangement of the chemical elements, organized on the basis of their atomic numbers, electron configurations and recurring chemical properties. Elements are presented in order of increasing atomic number, the standard form of the table consists of a grid of elements, with rows called periods and columns called groups. The history of the table reflects over a century of growth in the understanding of chemical properties. A number of elements have been known from antiquity, as they are found in their native form and are relatively simple to mine with primitive tools. The four roots, which were renamed as elements by Plato, were earth, water, air. Similar ideas about these four elements also existed in ancient traditions. While Aristotle and Plato understood the concept of an element, their ideas did nothing to advance the understanding of the nature of matter, the history of the periodic table is also a history of the discovery of the chemical elements. The first person in history to discover a new element was Hennig Brand, Brand tried to discover the Philosophers Stone — a mythical object that was supposed to turn inexpensive base metals into gold. In 1649, his experiments with distilled human urine resulted in the production of a white substance. He kept his secret until 1680, when Robert Boyle rediscovered phosphorus. The discovery of phosphorus helped to raise the question of what it meant for a substance to be an element, in 1661, Boyle defined an element as a substance that cannot be broken down into a simpler substance by a chemical reaction. This simple definition served for three centuries and lasted until the discovery of subatomic particles, Lavoisiers Traité Élémentaire de Chimie, which was written in 1789 and first translated into English by the writer Robert Kerr, is considered to be the first modern textbook about chemistry. Lavoisiers list also included light and caloric, which at the time were believed to be material substances and he has classified these substances into metals and non metals. While many leading chemists refused to believe Lavoisiers new revelations, the Elementary Treatise was written well enough to convince the younger generation, however, Lavoisiers descriptions of his elements lack completeness, as he only classified them as metals and non-metals. In 1817, Johann Wolfgang Döbereiner began to formulate one of the earliest attempts to classify the elements, in 1829, he found that he could form some of the elements into groups of three, with the members of each group having related properties. In 1862 he devised a form of periodic table, which he named Vis tellurique, after the element tellurium. With the elements arranged in a spiral on a cylinder by order of increasing atomic weight and his 1863 publication included a chart, but his original paper in the Comptes rendus de lAcadémie des sciences used geological rather than chemical terms and did not include a diagram. As a result, de Chancourtois ideas received little attention until after the work of Dmitri Mendeleev had been publicised, in 1864, the English chemist John Newlands classified the sixty-two known elements into eight groups, based on their physical properties
4.
Dmitri Mendeleev
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Dmitri Ivanovich Mendeleev was a Russian chemist and inventor. Mendeleev was born in the village of Verkhnie Aremzyani, near Tobolsk in Siberia, to Ivan Pavlovich Mendeleev and his grandfather was Pavel Maximovich Sokolov, a priest of the Russian Orthodox Church from the Tver region. Ivan, along with his brothers and sisters, obtained new family names while attending the theological seminary, Mendeleev was raised as an Orthodox Christian, his mother encouraging him to patiently search divine and scientific truth. His son would later inform that he departed from the Church, Mendeleev is thought to be the youngest of either 11,13,14 or 17 siblings, the exact number differs among sources. His father was a teacher of arts, politics and philosophy. Unfortunately for the familys financial well being, his father became blind and his mother was forced to work and she restarted her familys abandoned glass factory. At the age of 13, after the passing of his father, in 1849, his mother took Mendeleev across the entire state of Russia from Siberia to Moscow with the aim of getting Mendeleev a higher education. The university in Moscow did not accept him, the mother and son continued to St. Petersburg to the father’s alma mater. The now poor Mendeleev family relocated to Saint Petersburg, where he entered the Main Pedagogical Institute in 1850, after graduation, he contracted tuberculosis, causing him to move to the Crimean Peninsula on the northern coast of the Black Sea in 1855. While there he became a master of the Simferopol gymnasium №1. In 1857, he returned to Saint Petersburg with fully restored health, between 1859 and 1861, he worked on the capillarity of liquids and the workings of the spectroscope in Heidelberg. Later in 1861, he published a textbook named Organic Chemistry and this won him the Demidov Prize of the Petersburg Academy of Sciences. On 4 April 1862 he became engaged to Feozva Nikitichna Leshcheva, Mendeleev became a professor at the Saint Petersburg Technological Institute and Saint Petersburg State University in 1864, and 1865, respectively. In 1865 he became Doctor of Science for his dissertation On the Combinations of Water with Alcohol and he achieved tenure in 1867 at St. Petersburg University and started to teach inorganic chemistry, while succeeding Voskresenskii to this post. And by 1871 he had transformed Saint Petersburg into a recognized center for chemistry research. In 1876, he became obsessed with Anna Ivanova Popova and began courting her, in 1881 he proposed to her and his divorce from Leshcheva was finalized one month after he had married Popova in early 1882. Even after the divorce, Mendeleev was technically a bigamist, the Russian Orthodox Church required at least seven years before lawful remarriage and his divorce and the surrounding controversy contributed to his failure to be admitted to the Russian Academy of Sciences. His daughter from his marriage, Lyubov, became the wife of the famous Russian poet Alexander Blok
5.
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
6.
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
7.
Group 4 element
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Group 4 is a group of elements in the periodic table. It contains the elements titanium, zirconium, hafnium and rutherfordium and this group lies in the d-block of the periodic table. The group itself has not acquired a name, it belongs to the broader grouping of the transition metals. The three Group 4 elements that occur naturally are titanium, zirconium and hafnium, the first three members of the group share similar properties, all three are hard refractory metals under standard conditions. However, the fourth element rutherfordium, has been synthesized in the laboratory, all isotopes of rutherfordium are radioactive. So far, no experiments in a supercollider have been conducted to synthesize the next member of the group, unpenthexium, the chemistry of rutherfordium is not very established and therefore the rest of the section deals only with titanium, zirconium, and hafnium. All the elements of the group are metals with a high melting point. The reactivity is not always due to the rapid formation of a stable oxide layer. The oxides TiO2, ZrO2 and HfO2 are white solids with high melting points, as tetravalent transition metals, all three elements form various inorganic compounds, generally in the oxidation state of +4. For the first three metals, it has shown that they are resistant to concentrated alkalis, but halogens react with them to form tetrahalides. At higher temperatures, all three metals react with oxygen, nitrogen, carbon, boron, sulfur, and silicon, because of the lanthanide contraction of the elements in the fifth period, zirconium and hafnium have nearly identical ionic radii. The ionic radius of Zr4+ is 79 picometers and that of Hf4+ is 78 pm and this similarity results in nearly identical chemical behavior and in the formation of similar chemical compounds. The chemistry of hafnium is so similar to that of zirconium that a separation on chemical reactions was not possible, the melting points and boiling points of the compounds and the solubility in solvents are the major differences in the chemistry of these twin elements. Titanium is considerably different from the other two owing to the effects of the lanthanide contraction, the table below is a summary of the key physical properties of the group 4 elements. The four question-marked values are extrapolated, william Gregor, Franz Joseph Muller and Martin Heinrich Klaproth independently discovered titanium between 1791 and 1795. Klaproth named it for the Titans of Greek mythology, Klaproth also discovered zirconium in the mineral zircon in 1789 and named it after the already known Zirkonerde. Dirk Coster and Georg von Hevesy were the first to search for the new element in zirconium ores, hafnium was discovered by the two in 1923 in Copenhagen, Denmark, validating the original 1869 prediction of Mendeleev. While titanium and zirconium, as relatively abundant elements, were discovered in the late 18th century and this was only partly due to hafniums relative scarcity
8.
Boron group
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The boron group are the chemical elements in group 13 of the periodic table, comprising boron, aluminium, gallium, indium, thallium, and perhaps also the chemically uncharacterized nihonium. The elements in the group are characterized by having three electrons in their outer energy levels. These elements have also referred to as icosagens and triels. Boron is classified as a metalloid while the rest, with the exception of nihonium, are considered post-transition metals. Boron occurs sparsely, probably because bombardment by the particles produced from natural radioactivity disrupts its nuclei. Aluminium occurs widely on earth, and indeed is the third most abundant element in the Earths crust, gallium is found in the earth with an abundance of 13 ppm. Indium is the 61st most abundant element in the earths crust, nihonium is never found in nature and therefore is termed a synthetic element. Several group 13 elements have biological roles in the ecosystem, Boron is a trace element in humans and is essential for some plants. Lack of boron can lead to stunted plant growth, while an excess can cause harm by inhibiting growth. Aluminium has neither a biological role nor significant toxicity and is considered safe, indium and gallium can stimulate metabolism, gallium is credited with the ability to bind itself to iron proteins. Thallium is highly toxic, interfering with the function of numerous vital enzymes, Boron differs from the other group members in its hardness, refractivity and reluctance to participate in metallic bonding. An example of a trend in reactivity is borons tendency to form compounds with hydrogen. Most of the elements in the group show increasing reactivity as the elements get heavier in atomic mass. The simplest borane is diborane, or B2H6, the next group-13 elements, aluminium and gallium, form fewer stable hydrides, although both AlH3 and GaH3 exist. Indium, the element in the group, is not known to form many hydrides. No stable compound of thallium and hydrogen has been synthesized in any laboratory, all of the boron-group elements are known to form a trivalent oxide, with two atoms of the element bonded covalently with three atoms of oxygen. These elements show a trend of increasing pH, Boron oxide is slightly acidic, aluminium and gallium oxide are amphoteric, indium oxide is nearly amphoteric, and thallium oxide is a Lewis base because it dissolves in acids to form salts. Each of these compounds are stable, but thallium oxide decomposes at temperatures higher than 875 °C, the elements in group 13 are also capable of forming stable compounds with the halogens, usually with the formula MX3 The only exception to this is thallium iodide
9.
Chalcogen
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The chalcogens are the chemical elements in group 16 of the periodic table. This group is known as the oxygen family. It consists of the oxygen, sulfur, selenium, tellurium. The chemically uncharacterized synthetic element livermorium is predicted to be a chalcogen as well, the word chalcogen is derived from a combination of the Greek word khalkόs principally meaning copper, and the Latinised Greek word genēs, meaning born or produced. Sulfur has been known since antiquity, and oxygen was recognized as an element in the 18th century, selenium, tellurium and polonium were discovered in the 19th century, and livermorium in 2000. All of the chalcogens have six valence electrons, leaving them two electrons short of an outer shell. Their most common oxidation states are −2, +2, +4 and they have relatively low atomic radii, especially the lighter ones. Lighter chalcogens are typically nontoxic in their form, and are often critical to life. All of the chalcogens have some role in functions, either as a nutrient or a toxin. The lighter chalcogens, such as oxygen and sulfur, are rarely toxic, selenium is an important nutrient but is also commonly toxic. Tellurium often has unpleasant effects, and polonium is always extremely harmful, sulfur has more than 20 allotropes, oxygen has nine, selenium has at least five, polonium has two, and only one crystal structure of tellurium has so far been discovered. There are numerous organic chalcogen compounds, not counting oxygen, organic sulfur compounds are generally the most common, followed by organic selenium compounds and organic tellurium compounds. This trend also occurs with chalcogen pnictides and compounds containing chalcogens, oxygen is generally extracted from air and sulfur is extracted from oil and natural gas. Selenium and tellurium are produced as byproducts of copper refining, polonium and livermorium are most available in particle accelerators. The primary use of oxygen is in steelmaking. Sulfur is mostly converted into sulfuric acid, which is used in the chemical industry. Seleniums most common application is glassmaking, tellurium compounds are mostly used in optical disks, electronic devices, and solar cells. Some of poloniums applications are due to its radioactivity, all of the solid, stable chalcogens are soft and do not conduct heat well
10.
Noble gas
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The noble gases make a group of chemical elements with similar properties, under standard conditions, they are all odorless, colorless, monatomic gases with very low chemical reactivity. The six noble gases that occur naturally are helium, neon, argon, krypton, xenon, oganesson is predicted to be a noble gas as well, but its chemistry has not yet been investigated. For the first six periods of the table, the noble gases are exactly the members of group 18 of the periodic table. Noble gases are typically highly unreactive except when under particular extreme conditions, the inertness of noble gases makes them very suitable in applications where reactions are not wanted. The melting and boiling points for a noble gas are close together, differing by less than 10 °C. Neon, argon, krypton, and xenon are obtained from air in an air separation unit using the methods of liquefaction of gases, Noble gases have several important applications in industries such as lighting, welding, and space exploration. After the risks caused by the flammability of hydrogen became apparent, it was replaced with helium in blimps, Noble gas is translated from the German noun Edelgas, first used in 1898 by Hugo Erdmann to indicate their extremely low level of reactivity. The name makes an analogy to the noble metals, which also have low reactivity. The noble gases have also referred to as inert gases. Rare gases is another term that was used, but this is inaccurate because argon forms a fairly considerable part of the Earths atmosphere due to decay of radioactive potassium-40. Pierre Janssen and Joseph Norman Lockyer discovered a new element on August 18,1868 while looking at the chromosphere of the Sun, no chemical analysis was possible at the time, but helium was later found to be a noble gas. Before them, in 1784, the English chemist and physicist Henry Cavendish had discovered that air contains a proportion of a substance less reactive than nitrogen. A century later, in 1895, Lord Rayleigh discovered that samples of nitrogen from the air were of a different density than nitrogen resulting from chemical reactions, with this discovery, they realized an entire class of gases was missing from the periodic table. During his search for argon, Ramsay also managed to isolate helium for the first time while heating cleveite, Ramsay continued to search for these gases using the method of fractional distillation to separate liquid air into several components. In 1898, he discovered the elements krypton, neon, and xenon, and named them after the Greek words κρυπτός, νέος, and ξένος, respectively. Rayleigh and Ramsay received the 1904 Nobel Prizes in Physics and in Chemistry, respectively, for their discovery of the noble gases, the discovery of the noble gases aided in the development of a general understanding of atomic structure. In 1895, French chemist Henri Moissan attempted to form a reaction between fluorine, the most electronegative element, and argon, one of the noble gases, but failed. Scientists were unable to prepare compounds of argon until the end of the 20th century, in 1962, Neil Bartlett discovered the first chemical compound of a noble gas, xenon hexafluoroplatinate
11.
Period 2 element
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A period 2 element is one of the chemical elements in the second row of the periodic table of the chemical elements. The second period contains the elements lithium, beryllium, boron, carbon, nitrogen, oxygen, fluorine and this situation can be explained by modern theories of atomic structure. In a quantum description of atomic structure, this period corresponds to the filling of the 2s. Period 2 elements obey the rule in that they need eight electrons to complete their valence shell. The maximum number of electrons that these elements can accommodate is ten, all of the elements in the period can form diatomic molecules except beryllium and neon. Period 2 is the first period in the table that periodic trends can be drawn from. Period 1, which contains two elements is too small to draw any conclusive trends from it, especially because the two elements behave nothing like other s-block elements. Period 2 has much more conclusive trends, for all elements in period 2, as the atomic number increases, the atomic radius of the elements decreases, the electronegativity increases, and the ionization energy increases. Period 2 only has two metals, making it the least metallic period and the most nonmetals, with four. All period 2 elements completely obey the Madelung rule, in period 2s, lithium and beryllium fill the 2s subshell, and boron, carbon, nitrogen, oxygen, fluorine, and neon fill the 2p subshell. The period shares this trait with periods 1 and 3, none of which contain elements or inner transition elements. Lithium is a metal with atomic number 3, occurring naturally in two isotopes, 6Li and 7Li. The two make up all natural occurrence of lithium on Earth, although further isotopes have been synthesized, in ionic compounds, lithium loses an electron to become positively charged, forming the cation Li+. Lithium is the first alkali metal in the table. At standard temperature and pressure, lithium is a soft, silver-white, with a density of 0.564 g·cm−3, lithium is the lightest metal and the least dense solid element. According to theory, Lithium is one of the few elements synthesized in the Big Bang, making it a primordial element. Lithium is the 33rd most abundant element on earth, occurring in concentrations of between 20 and 70 ppm by weight, but due to its high reactivity it is found naturally in compounds. Lithium salts are used in the industry as mood stabilising drugs
