1.
Petrology
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Petrology is the branch of geology that studies the origin, composition, distribution and structure of rocks. In the petroleum industry, lithology, or more specifically mud logging, is the representation of geological formations being drilled through. As the cuttings are circulated out of the borehole they are sampled, examined and tested chemically when needed, Petrology utilizes the fields of mineralogy, petrography, optical mineralogy, and chemical analysis to describe the composition and texture of rocks. Igneous rocks include volcanic and plutonic rocks, sedimentary petrology focuses on the composition and texture of sedimentary rocks. Experiments are particularly useful for investigating rocks of the lower crust and they are also one of the prime sources of information about completely inaccessible rocks such as those in the Earths lower mantle and in the mantles of the other terrestrial planets and the Moon. The work of experimental petrologists has laid a foundation on which modern understanding of igneous, important publications in petrology Ore Soil Best, Myron G. Igneous and Metamorphic Petrology. ISBN 1-4051-0588-7 Blatt, Harvey, Tracy, Robert J. Owens, Brent, Petrology, igneous, sedimentary, ISBN 978-0-7167-3743-8 Dietrich, Richard Vincent, Skinner, Brian J. Gems, Granites, and Gravels, knowing and using rocks and minerals. ISBN 978-0-521-10722-8 Fei, Yingwei, Bertka, Constance M. Mysen, mantle Petrology, field observations and high-pressure experimentation. ISBN 0-941809-05-6 Philpotts, Anthony, Ague, Jay, Principles of Igneous and Metamorphic Petrology
2.
Chemical element
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A chemical element or element is a species of atoms having the same number of protons in their atomic nuclei. There are 118 elements that have identified, of which the first 94 occur naturally on Earth with the remaining 24 being synthetic elements. There are 80 elements that have at least one stable isotope and 38 that have exclusively radioactive isotopes, iron is the most abundant element making up Earth, while oxygen is the most common element in the Earths crust. Chemical elements constitute all of the matter of the universe. The two lightest elements, hydrogen and helium, were formed in the Big Bang and are the most common elements in the universe. The next three elements were formed mostly by cosmic ray spallation, and are rarer than those that follow. Formation of elements with from 6 to 26 protons occurred and continues to occur in main sequence stars via stellar nucleosynthesis, the high abundance of oxygen, silicon, and iron on Earth reflects their common production in such stars. The term element is used for atoms with a number of protons as well as for a pure chemical substance consisting of a single element. A single element can form multiple substances differing in their structure, when different elements are chemically combined, with the atoms held together by chemical bonds, they form chemical compounds. Only a minority of elements are found uncombined as relatively pure minerals, among the more common of such native elements are copper, silver, gold, carbon, and sulfur. All but a few of the most inert elements, such as gases and noble metals, are usually found on Earth in chemically combined form. While about 32 of the elements occur on Earth in native uncombined forms. For example, atmospheric air is primarily a mixture of nitrogen, oxygen, and argon, the history of the discovery and use of the elements began with primitive human societies that found native elements like carbon, sulfur, copper and gold. Later civilizations extracted elemental copper, tin, lead and iron from their ores by smelting, using charcoal, alchemists and chemists subsequently identified many more, almost all of the naturally occurring elements were known by 1900. Save for unstable radioactive elements with short half-lives, all of the elements are available industrially, almost all other elements found in nature were made by various natural methods of nucleosynthesis. On Earth, small amounts of new atoms are produced in nucleogenic reactions, or in cosmogenic processes. Of the 94 naturally occurring elements, those with atomic numbers 1 through 82 each have at least one stable isotope, Isotopes considered stable are those for which no radioactive decay has yet been observed. Elements with atomic numbers 83 through 94 are unstable to the point that radioactive decay of all isotopes can be detected, the very heaviest elements undergo radioactive decay with half-lives so short that they are not found in nature and must be synthesized
3.
Ion
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An ion is an atom or a molecule in which the total number of electrons is not equal to the total number of protons, giving the atom or molecule a net positive or negative electrical charge. Ions can be created, by chemical or physical means. In chemical terms, if an atom loses one or more electrons. If an atom gains electrons, it has a net charge and is known as an anion. Ions consisting of only a single atom are atomic or monatomic ions, because of their electric charges, cations and anions attract each other and readily form ionic compounds, such as salts. In the case of ionization of a medium, such as a gas, which are known as ion pairs are created by ion impact, and each pair consists of a free electron. The word ion comes from the Greek word ἰόν, ion, going and this term was introduced by English physicist and chemist Michael Faraday in 1834 for the then-unknown species that goes from one electrode to the other through an aqueous medium. Faraday also introduced the words anion for a charged ion. In Faradays nomenclature, cations were named because they were attracted to the cathode in a galvanic device, arrhenius explanation was that in forming a solution, the salt dissociates into Faradays ions. Arrhenius proposed that ions formed even in the absence of an electric current, ions in their gas-like state are highly reactive, and do not occur in large amounts on Earth, except in flames, lightning, electrical sparks, and other plasmas. These gas-like ions rapidly interact with ions of charge to give neutral molecules or ionic salts. These stabilized species are commonly found in the environment at low temperatures. A common example is the present in seawater, which are derived from the dissolved salts. Electrons, due to their mass and thus larger space-filling properties as matter waves, determine the size of atoms. Thus, anions are larger than the parent molecule or atom, as the excess electron repel each other, as such, in general, cations are smaller than the corresponding parent atom or molecule due to the smaller size of its electron cloud. One particular cation contains no electrons, and thus consists of a single proton - very much smaller than the parent hydrogen atom. Since the electric charge on a proton is equal in magnitude to the charge on an electron, an anion, from the Greek word ἄνω, meaning up, is an ion with more electrons than protons, giving it a net negative charge. A cation, from the Greek word κατά, meaning down, is an ion with fewer electrons than protons, there are additional names used for ions with multiple charges
4.
Mineral
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A mineral is a naturally occurring chemical compound, usually of crystalline form and abiogenic in origin. A mineral has one specific chemical composition, whereas a rock can be an aggregate of different minerals or mineraloids, the study of minerals is called mineralogy. There are over 5,300 known mineral species, over 5,070 of these have been approved by the International Mineralogical Association, the silicate minerals compose over 90% of the Earths crust. The diversity and abundance of species is controlled by the Earths chemistry. Silicon and oxygen constitute approximately 75% of the Earths crust, which translates directly into the predominance of silicate minerals, minerals are distinguished by various chemical and physical properties. Differences in chemical composition and crystal structure distinguish the various species, changes in the temperature, pressure, or bulk composition of a rock mass cause changes in its minerals. Minerals can be described by their various properties, which are related to their chemical structure. Common distinguishing characteristics include crystal structure and habit, hardness, lustre, diaphaneity, colour, streak, tenacity, cleavage, fracture, parting, more specific tests for describing minerals include magnetism, taste or smell, radioactivity and reaction to acid. Minerals are classified by key chemical constituents, the two dominant systems are the Dana classification and the Strunz classification, the silicate class of minerals is subdivided into six subclasses by the degree of polymerization in the chemical structure. All silicate minerals have a unit of a 4− silica tetrahedron—that is, a silicon cation coordinated by four oxygen anions. These tetrahedra can be polymerized to give the subclasses, orthosilicates, disilicates, cyclosilicates, inosilicates, phyllosilicates, other important mineral groups include the native elements, sulfides, oxides, halides, carbonates, sulfates, and phosphates. The first criterion means that a mineral has to form by a natural process, stability at room temperature, in the simplest sense, is synonymous to the mineral being solid. More specifically, a compound has to be stable or metastable at 25 °C, modern advances have included extensive study of liquid crystals, which also extensively involve mineralogy. Minerals are chemical compounds, and as such they can be described by fixed or a variable formula, many mineral groups and species are composed of a solid solution, pure substances are not usually found because of contamination or chemical substitution. Finally, the requirement of an ordered atomic arrangement is usually synonymous with crystallinity, however, crystals are also periodic, an ordered atomic arrangement gives rise to a variety of macroscopic physical properties, such as crystal form, hardness, and cleavage. There have been recent proposals to amend the definition to consider biogenic or amorphous substances as minerals. The formal definition of an approved by the IMA in 1995, A mineral is an element or chemical compound that is normally crystalline. However, if geological processes were involved in the genesis of the compound, Mineral classification schemes and their definitions are evolving to match recent advances in mineral science
5.
Partition coefficient
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In the physical sciences, a partition-coefficient or distribution-coefficient is the ratio of concentrations of a compound in a mixture of two immiscible phases at equilibrium. This ratio is therefore a measure of the difference in solubility of the compound in two phases. In the chemical and pharmaceutical sciences, both phases usually are solvents, most commonly, one of the solvents is water while the second is hydrophobic such as 1-octanol. Hence the partition coefficient measures how hydrophilic or hydrophobic a chemical substance is, partition coefficients are useful in estimating the distribution of drugs within the body. Hydrophobic drugs with high octanol/water partition coefficients are distributed to hydrophobic areas such as lipid bilayers of cells. Conversely hydrophilic drugs are primarily in aqueous regions such as blood serum. If one of the solvents is a gas and the other a liquid, for example, the blood/gas partition coefficient of a general anesthetic measures how easily the anesthetic passes from gas to blood. Partition coefficients can also be defined one of the phases is solid, for instance, when one phase is a molten metal. The partitioning of a substance into a solid results in a solid solution, partition coefficients can be measured experimentally in various ways or estimated via calculation based on a variety of methods. Despite formal recommendation to the contrary, the partition coefficient remains the predominantly used term in the scientific literature. In contrast, the IUPAC recommends that the term no longer be used, rather. When one of the solvents is water and the other is a non-polar solvent, for measurements of distribution coefficients, the pH of the aqueous phase is buffered to a specific value such that the pH is not significantly perturbed by the introduction of the compound. In addition, since log D is pH-dependent, the pH at which the log D was measured must be specified. In areas such as drug discovery—areas involving partition phenomena in systems such as the human body—the log D at the physiologic pH,7.4, is of particular interest. It is often convenient to express the log D in terms of P I, defined above, the values in the following table are from the Dortmund Data Bank. They are sorted by the coefficient, smallest to largest. Values for other compounds may be found in a variety of available reviews, critical discussions of the challenges of measurement of log P, and related computation of its estimated values, appear in several reviews. Hence, the log P of a molecule is one used in decision-making by medicinal chemists in pre-clinical drug discovery, for example
6.
Magma
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Besides molten rock, magma may also contain suspended crystals, dissolved gas and sometimes gas bubbles. Magma often collects in magma chambers that may feed a volcano or solidify underground to form an intrusion, magma is capable of intruding into adjacent rocks, extrusion onto the surface as lava, and explosive ejection as tephra to form pyroclastic rock. Magma is a complex high-temperature fluid substance, temperatures of most magmas are in the range 700 °C to 1300 °C, but very rare carbonatite magmas may be as cool as 600 °C, and komatiite magmas may have been as hot as 1600 °C. Environments of magma formation and compositions are commonly correlated, environments include subduction zones, continental rift zones, mid-ocean ridges and hotspots. Despite being found in such locales, the bulk of the Earths crust. Except for the outer core, most of the Earth takes the form of a rheid. Magma, as liquid, preferentially forms in high temperature, low pressure environments within several kilometers of the Earths surface, magma compositions may evolve after formation by fractional crystallization, contamination, and magma mixing. By definition rock formed of solidified magma is called igneous rock, melting of solid rocks to form magma is controlled by three physical parameters, temperature, pressure, and composition. Mechanisms are discussed in the entry for igneous rock, as a rock melts, its volume changes. When enough rock is melted, the small globules of melt link up, under pressure within the earth, as little as a fraction of a percent partial melting may be sufficient to cause melt to be squeezed from its source. The degree of melting is critical for determining what type of magma is produced. The degree of partial melting required to form a melt can be estimated by considering the relative enrichment of incompatible elements versus compatible elements, incompatible elements commonly include potassium, barium, cesium, and rubidium. Rock types produced by small degrees of melting in the Earths mantle are typically alkaline. Typically, primitive melts of this composition form lamprophyre, lamproite, kimberlite and sometimes nepheline-bearing mafic rocks such as alkali basalts, pegmatite may be produced by low degrees of partial melting of the crust. Some granite-composition magmas are eutectic melts, and they may be produced by low to high degrees of melting of the crust. At high degrees of melting of the crust, granitoids such as tonalite, granodiorite and monzonite can be produced. Being only the time in recorded history that magma had been reached, IDDP decided to invest in the hole. A cemented steel case was constructed in the hole with a perforation at the close to the magma
7.
Fractional crystallization (geology)
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Fractional crystallization, or crystal fractionation, is one of the most important geochemical and physical processes operating within the Earths crust and mantle. It is one of the processes of magmatic differentiation. Fractional crystallization is the removal and segregation from a melt of mineral precipitates, except in special cases, in essence, fractional crystallization is the removal of early formed crystals from an originally homogeneous magma so that these crystals are prevented from further reaction with the residual melt. The composition of the melt becomes relatively depleted in some components and enriched in others. Addition and loss of water, carbon dioxide, hydrogen, for example, the partial pressure of water in silicate melts can be of prime importance, as in near-solidus crystallization of magmas of granite composition. Experiments have provided examples of the complexities that control which mineral is crystallized first as the melt cools down past the liquidus. One example concerns crystallization of melts that form mafic and ultramafic rocks, mgO and SiO2 concentrations in melts are among the variables that determine whether forsterite olivine or enstatite pyroxene is precipitated, but the water content and pressure are also important. In some compositions, at high pressures without water crystallization of enstatite is favored, granitic magmas provide additional examples of how melts of generally similar composition and temperature, but at different pressure, may crystallize different minerals. Pressure determines the water content of a magma of granite composition. During the process of crystallization, melts become enriched in incompatible elements. Hence, knowledge of the sequence is critical in understanding how melt compositions evolve. Textures of rocks provide insights, as documented in the early 1900s by Bowens reaction series, a variety of Cr, Fe, and Ti oxides show such textures, like intergranular chromite in a siliceous matrix. Experimentally-determined phase diagrams for simple mixtures provide insights into general principles, numerical calculations with special software have become increasingly able to simulate natural processes accurately. Cumulate rock Flow banding Fractional crystallization Igneous differentiation Layered intrusion
8.
Mantle (geology)
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The mantle is a layer inside a terrestrial planet and some other rocky planetary bodies. For a mantle to form, the body must be large enough to have undergone the process of planetary differentiation by density. The mantle surrounds the planetary core, the mantle is surrounded by the crust. The terrestrial planets, the Moon, two of Jupiters moons and the asteroid Vesta each have a made of silicate rock. Interpretation of spacecraft data suggests that at least two moons of Jupiter, as well as Titan and Triton each have a mantle made of ice or other solid volatile substances. The interior of Earth, similar to the terrestrial planets, is divided into layers of different composition. The mantle is a layer between the crust and the outer core, Earths mantle is a silicate rocky shell with an average thickness of 2,886 kilometres. The mantle makes up about 84% of Earths volume and it is predominantly solid but in geological time it behaves as a very viscous fluid. The mantle encloses the hot core rich in iron and nickel, past episodes of melting and volcanism at the shallower levels of the mantle have produced a thin crust of crystallized melt products near the surface. A thin crust, the part of the lithosphere, surrounds the mantle and is about 5 to 75 km thick. In some places under the ocean the mantle is exposed on the surface of Earth. The mantle is divided into sections which are based upon results from seismology and these layers are the following, the upper mantle, the transition zone, the lower mantle, and anomalous core–mantle boundary with a variable thickness. The uppermost mantle plus overlying crust are relatively rigid and form the lithosphere, below the lithosphere the upper mantle becomes notably more plastic. In some regions below the lithosphere, the shear velocity is reduced. Inge Lehmann discovered a seismic discontinuity at about 220 km depth, although this discontinuity has been found in other studies, the transition zone is an area of great complexity, it physically separates the upper and lower mantle. Very little is known about the lower mantle apart from that it appears to be relatively seismically homogeneous, the D layer at the core–mantle boundary separates the mantle from the core. A principal source of the heat that drives plate tectonics is the decay of uranium, thorium. The mantle differs substantially from the crust in its properties as the direct consequence of the difference in composition
9.
Crust (geology)
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In geology, the crust is the outermost solid shell of a rocky planet or natural satellite, which is chemically distinct from the underlying mantle. The crust of the Earth is composed of a variety of igneous, metamorphic. The crust is underlain by the mantle, the upper part of the mantle is composed mostly of peridotite, a rock denser than rocks common in the overlying crust. The boundary between the crust and mantle is conventionally placed at the Mohorovičić discontinuity, a boundary defined by a contrast in seismic velocity, the crust occupies less than 1% of Earths volume. The crust of the Earth is of two types, oceanic and continental. The oceanic crust is 5 km to 10 km thick and is composed primarily of basalt, diabase, the continental crust is typically from 30 km to 50 km thick and is mostly composed of slightly less dense rocks than those of the oceanic crust. Some of these less dense rocks, such as granite, are common in the continental crust, both the continental and oceanic crust float on the mantle. Because the continental crust is thicker, it both to greater elevations and greater depth than the oceanic crust. The slightly lower density of continental rock compared to basaltic oceanic rock contributes to the higher relative elevation of the top of the continental crust. As the top of the continental crust reaches elevations higher than that of the oceanic, the temperature of the crust increases with depth, reaching values typically in the range from about 200 °C to 400 °C at the boundary with the underlying mantle. The crust and underlying relatively rigid uppermost mantle make up the lithosphere, because of convection in the underlying plastic upper mantle and asthenosphere, the lithosphere is broken into tectonic plates that move. The temperature increases by as much as 30 °C for every kilometer locally in the part of the crust. Earth has probably always had some form of basaltic crust, in contrast, the bulk of the continental crust is much older. The oldest continental crustal rocks on Earth have ages in the range from about 3.7 to 4, some zircon with age as great as 4.3 billion years has been found in the Narryer Gneiss Terrane. The average age of the current Earths continental crust has been estimated to be about 2.0 billion years, most crustal rocks formed before 2.5 billion years ago are located in cratons. Such old continental crust and the underlying mantle asthenosphere are less dense than elsewhere in Earth, formation of new continental crust is linked to periods of intense orogeny, these periods coincide with the formation of the supercontinents such as Rodinia, Pangaea and Gondwana. The continental crust has a composition similar to that of andesite. The most abundant minerals in Earths continental crust are feldspars, which make up about 41% of the crust by weight, followed by quartz at 12%, Continental crust is enriched in incompatible elements compared to the basaltic ocean crust and much enriched compared to the underlying mantle
10.
Phase (matter)
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In the physical sciences, a phase is a region of space, throughout which all physical properties of a material are essentially uniform. Examples of physical properties include density, index of refraction, magnetization, a simple description is that a phase is a region of material that is chemically uniform, physically distinct, and mechanically separable. In a system consisting of ice and water in a jar, the ice cubes are one phase, the water is a second phase. The glass of the jar is another separate phase, the term phase is sometimes used as a synonym for state of matter, but there can be several immiscible phases of the same state of matter. Also, the phase is sometimes used to refer to a set of equilibrium states demarcated in terms of state variables such as pressure and temperature by a phase boundary on a phase diagram. Distinct phases may be described as different states of such as gas, liquid, solid. Useful mesophases between solid and liquid form other states of matter, distinct phases may also exist within a given state of matter. As shown in the diagram for iron alloys, several phases exist for both the solid and liquid states, phases may also be differentiated based on solubility as in polar or non-polar. A mixture of water and oil will separate into two phases. Water has a low solubility in oil, and oil has a low solubility in water. Solubility is the amount of a solute that can dissolve in a solvent before the solute ceases to dissolve. A mixture can separate into more than two phases and the concept of phase separation extends to solids, i. e. solids can form solid solutions or crystallize into distinct crystal phases. Metal pairs that are mutually soluble can form alloys, whereas metal pairs that are mutually insoluble cannot, as many as eight immiscible liquid phases have been observed. Mutually immiscible liquid phases are formed from water, hydrophobic solvents, perfluorocarbons, silicones, several different metals. Not all organic solvents are completely miscible, e. g. a mixture of ethylene glycol, phases do not need to macroscopically separate spontaneously. Emulsions and colloids are examples of immiscible phase pair combinations that do not physically separate, left to equilibration, many compositions will form a uniform single phase, but depending on the temperature and pressure even a single substance may separate into two or more distinct phases. Within each phase, the properties are uniform but between the two phases properties differ, water in a closed jar with an air space over it forms a two phase system. Most of the water is in the phase, where it is held by the mutual attraction of water molecules
11.
Ionic radius
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Ionic radius, rion, is the radius of an atoms ion. Ionic radii are given in units of either picometers or angstroms. Typical values range from 30 pm to over 200 pm, ions may be larger or smaller than the neutral atom, depending on the ions electric charge. When an atom loses an electron to form a cation, the electrons are more strongly attracted to the nucleus. Similarly, when an electron is added to an atom, forming an anion, the ionic radius is not a fixed property of a given ion, but varies with coordination number, spin state and other parameters. Nevertheless, ionic radius values are sufficiently transferable to allow periodic trends to be recognized, as with other types of atomic radius, ionic radii increase on descending a group. Ionic size also increases with increasing number, and an ion in a high-spin state will be larger than the same ion in a low-spin state. In general, ionic radius decreases with increasing positive charge and increases with increasing negative charge, an anomalous ionic radius in a crystal is often a sign of significant covalent character in the bonding. No bond is ionic, and some supposedly ionic compounds. This is illustrated by the cell parameters for sodium and silver halides in the table. On the basis of the fluorides, one would say that Ag+ is larger than Na+, the distance between two ions in an ionic crystal can be determined by X-ray crystallography, which gives the lengths of the sides of the unit cell of a crystal. For example, the length of each edge of the cell of sodium chloride is found to be 564.02 pm. Each edge of the cell of sodium chloride may be considered to have the atoms arranged as Na+∙∙∙Cl−∙∙∙Na+. Therefore, the distance between the Na+ and Cl− ions is half of 564.02 pm, which is 282.01 pm. However, although X-ray crystallography gives the distance between ions, it doesnt indicate where the boundary is between those ions, so it doesnt directly give ionic radii. Landé estimated ionic radii by considering crystals in which the anion and cation have a difference in size. The lithium ions are so much smaller than the ions that the lithium fits into holes within the crystal lattice. That is, the distance between two neighboring iodides in the crystal is assumed to be twice the radius of the iodide ion and this value can be used to determine other radii
12.
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
13.
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
14.
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
15.
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
16.
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
17.
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
18.
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
19.
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
20.
Rare-earth element
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Scandium and yttrium are considered rare earth elements because they tend to occur in the same ore deposits as the lanthanides and exhibit similar chemical properties. They are not especially rare, but they tend to occur together in nature and are difficult to separate from one another, however, because of their geochemical properties, rare earth elements are typically dispersed and not often found concentrated as rare earth minerals in economically exploitable ore deposits. The first such mineral discovered was gadolinite, a composed of cerium, yttrium, iron, silicon. This mineral was extracted from a mine in the village of Ytterby in Sweden, a table listing the seventeen rare earth elements, their atomic number and symbol, the etymology of their names, and their main usages is provided here. The distinction between the groups is more to do with atomic volume and geological behavior, Rare earth elements became known to the world with the discovery of the black mineral Ytterbite by Lieutenant Carl Axel Arrhenius in 1787, at a quarry in the village of Ytterby, Sweden. Arrheniuss ytterbite reached Johan Gadolin, a Royal Academy of Turku professor, anders Gustav Ekeberg isolated beryllium from the gadolinite but failed to recognize other elements that the ore contained. After this discovery in 1794 a mineral from Bastnäs near Riddarhyttan, Sweden, in 1803 they obtained a white oxide and called it ceria. Martin Heinrich Klaproth independently discovered the same oxide and called it ochroia, in 1839 Carl Gustav Mosander, an assistant of Berzelius, separated ceria by heating the nitrate and dissolving the product in nitric acid. He called the oxide of the soluble salt lanthana and it took him three more years to separate the lanthana further into didymia and pure lanthana. Didymia, although not further separable by Mosanders techniques, was a mixture of oxides, in 1842 Mosander also separated the yttria into three oxides, pure yttria, terbia and erbia. The earth giving pink salts he called terbium, the one that yielded yellow peroxide he called erbium, so in 1842 the number of known rare earth elements had reached six, yttrium, cerium, lanthanum, didymium, erbium and terbium. This confusion led to false claims of new elements, such as the mosandrium of J. Lawrence Smith. There were no further discoveries for 30 years, and the element didymium was listed in the table of elements with a molecular mass of 138. In 1879 Delafontaine used the new process of optical-flame spectroscopy. Also in 1879, the new element samarium was isolated by Paul Émile Lecoq de Boisbaudran from the mineral samarskite, the samaria earth was further separated by Lecoq de Boisbaudran in 1886 and a similar result was obtained by Jean Charles Galissard de Marignac by direct isolation from samarskite. They named the element gadolinium after Johan Gadolin, and its oxide was named gadolinia, the fractional crystallization of the oxides then yielded europium in 1901. In 1839 the third source for rare earths became available and this is a mineral similar to gadolinite, uranotantalum. This mineral from Miass in the southern Ural Mountains was documented by Gustave Rose, the exact number of rare earth elements that existed was highly unclear, and a maximum number of 25 was estimated
21.
Thorium
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Thorium is a chemical element with symbol Th and atomic number 90. A radioactive actinide metal, thorium is one of only two significantly radioactive elements that occur naturally in large quantities as a primordial element. It was discovered in 1829 by the Norwegian amateur mineralogist Morten Thrane Esmark and identified by the Swedish chemist Jöns Jacob Berzelius, who named it after Thor, a thorium atom has 90 protons and therefore 90 electrons, of which four are valence electrons. Thorium metal is silvery and tarnishes black when exposed to air, Thorium is weakly radioactive, all of its known isotopes are unstable. Thorium-232, which has 142 neutrons, is the most stable isotope of thorium and accounts for all natural thorium. Thorium is estimated to be three to four times more abundant than uranium in the Earths crust, and is chiefly refined from monazite sands as a by-product of extracting rare earth metals. Thorium was once used as the light source in gas mantles and as an alloying material. Thorium is still used as an alloying element in TIG welding electrodes. Thorium is predicted to be able to replace uranium as fuel in nuclear reactors. Thorium is a soft, paramagnetic, bright silvery radioactive actinide metal, in the periodic table, it is located to the right of the actinide actinium, to the left of the actinide protactinium, and below the lanthanide cerium. Pure thorium is very ductile and, as normal for metals, can be cold-rolled, swaged, at room temperature, thorium metal has a face-centred cubic crystal structure, additionally, it has two other forms at exotic conditions, one at high temperature and one at high pressure. The properties of thorium vary widely depending on the amount of impurities in the sample, the purest thorium specimens usually contain about a tenth of a percent of the dioxide. These values lie intermediate between those of its neighbours actinium and protactinium, showing the continuity of trends across the early actinides, thoriums melting point of 1750 °C is above both that of actinium and that of protactinium. After thorium, there is a new smooth trend downward in the points of the early actinides from thorium to plutonium where the number of f electrons increases from about 0. Thorium has a modulus of 54 GPa, comparable to those of tin. The hardness of thorium is similar to that of steel, so heated pure thorium can be rolled in sheets. Nevertheless, while thorium is nearly half as dense as uranium and plutonium, Thorium becomes superconductive below 1.4 K. Thorium can also form alloys with many other metals. With chromium and uranium, it forms eutectic mixtures, and thorium is completely miscible in both solid and liquid states with its lighter congener cerium, as such, 232Th still occurs naturally today, four-fifths of the thorium present at Earths formation has survived to the present
22.
Uranium
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Uranium is a chemical element with symbol U and atomic number 92. It is a metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons, Uranium is weakly radioactive because all its isotopes are unstable. The most common isotopes in natural uranium are uranium-238 and uranium-235, Uranium has the highest atomic weight of the primordially occurring elements. Its density is about 70% higher than that of lead, and it occurs naturally in low concentrations of a few parts per million in soil, rock and water, and is commercially extracted from uranium-bearing minerals such as uraninite. In nature, uranium is found as uranium-238, uranium-235, Uranium decays slowly by emitting an alpha particle. The half-life of uranium-238 is about 4.47 billion years, many contemporary uses of uranium exploit its unique nuclear properties. Uranium-235 is the naturally occurring fissile isotope, which makes it widely used in nuclear power plants. However, because of the amounts found in nature, uranium needs to undergo enrichment so that enough uranium-235 is present. Uranium-238 is fissionable by fast neutrons, and is fertile, meaning it can be transmuted to fissile plutonium-239 in a nuclear reactor, another fissile isotope, uranium-233, can be produced from natural thorium and is also important in nuclear technology. In sufficient concentration, these maintain a sustained nuclear chain reaction. This generates the heat in nuclear reactors, and produces the fissile material for nuclear weapons. Depleted uranium is used in kinetic energy penetrators and armor plating, Uranium is used as a colorant in uranium glass, producing lemon yellow to green colors. Uranium glass fluoresces green in ultraviolet light and it was also used for tinting and shading in early photography. The 1789 discovery of uranium in the mineral pitchblende is credited to Martin Heinrich Klaproth, eugène-Melchior Péligot was the first person to isolate the metal and its radioactive properties were discovered in 1896 by Henri Becquerel. An ensuing arms race during the Cold War between the United States and the Soviet Union produced tens of thousands of weapons that used uranium metal. The security of those weapons and their fissile material following the breakup of the Soviet Union in 1991 is a concern for public health. When refined, uranium is a white, weakly radioactive metal
23.
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
24.
Lanthanide
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The lanthanide /ˈlænθənaɪd/ or lanthanoid /ˈlænθənɔɪd/ series of chemical elements comprises the fifteen metallic chemical elements with atomic numbers 57 through 71, from lanthanum through lutetium. These fifteen lanthanide elements, along with the similar elements scandium and yttrium, are often collectively known as the rare earth elements. The informal chemical symbol Ln is used in discussions of lanthanide chemistry to refer to any lanthanide. All lanthanide elements form trivalent cations, Ln3+, whose chemistry is largely determined by the ionic radius and they are termed lanthanides because the lighter elements in the series are chemically similar to lanthanum. Strictly speaking, both lanthanum and lutetium have been labeled as group 3 elements, because both have a single valence electron in the 5d shell. However, both elements are included in any general discussion of the chemistry of the lanthanide elements. Together with scandium and yttrium, the trivial name rare earths is sometimes used to all the lanthanides. This name arises from the minerals from which they were isolated, however, the use of the name is deprecated by IUPAC, as the elements are neither rare in abundance nor earths. Despite their abundance, even the technical term lanthanides could be interpreted to reflect a sense of elusiveness on the part of elements, as it comes from the Greek λανθανειν. However, if not referring to their abundance, but rather to their property of hiding behind each other in minerals. The term lanthanide was introduced by Victor Goldschmidt in 1925, the hybridisation is believed to be at its greatest for cerium, which has the lowest melting point of all,795 °C. The lanthanide metals are soft, their hardness increases across the series, europium stands out, as it has the lowest density in the series at 5.24 g/cm3 and the largest metallic radius in the series at 208.4 pm. It can be compared to barium, which has a radius of 222 pm. It is believed that the contains the larger Eu2+ ion. Ytterbium also has a metallic radius, and a similar explanation is suggested. The resistivities of the metals are relatively high, ranging from 29 to 134 μ-ohm·cm. These values can be compared to a conductor such as aluminium. With the exceptions of La, Yb, and Lu, the lanthanides are strongly paramagnetic, gadolinium becomes ferromagnetic at below 16 °C
25.
Lanthanum
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Lanthanum is a soft, ductile, silvery-white metallic chemical element with symbol La and atomic number 57. It tarnishes rapidly when exposed to air and is enough to be cut with a knife. It is the eponym of the series, a group of 15 similar elements between lanthanum and lutetium in the periodic table, of which lanthanum is the first and the prototype. It is also considered the first element of the 6th-period transition metals and is traditionally counted among the rare earth elements. The usual oxidation state is +3, lanthanum has no biological role and is not very toxic. Lanthanum usually occurs together with cerium and the rare earth elements. Lanthanum was first found by the Swedish chemist Carl Gustav Mosander in 1839 as an impurity in cerium nitrate – hence the name lanthanum, from the Ancient Greek λανθάνειν, meaning to lie hidden. Although it is classified as a rare element, lanthanum is the 28th most abundant element in the Earths crust, almost three times as abundant as lead. In minerals such as monazite and bastnäsite, lanthanum composes about a quarter of the lanthanide content and it is extracted from those minerals by a process of such complexity that pure lanthanum metal was not isolated until 1923. Lanthanum carbonate is used as a binder in cases of renal failure. Lanthanum is the first element and prototype of the lanthanide series, in the periodic table, it appears to the right of the alkaline earth metal barium and to the left of the lanthanide cerium. Similarly to scandium, yttrium, and actinium, the 57 electrons of an atom are arranged in the configuration 5d16s2. Some lanthanum compounds are known, but they are much less stable. Thus it is very weakly paramagnetic, unlike the strongly paramagnetic later lanthanides. The lanthanides become harder as the series is traversed, as expected, lanthanum has a relatively high resistivity of 615 nΩm at room temperature, in comparison, the value for the good conductor aluminium is only 26.50 nΩm. Lanthanum is the least volatile of the lanthanides, like most of the lanthanides, lanthanum has a hexagonal crystal structure at room temperature. At 310 °C, lanthanum changes to a cubic structure. As expected from periodic trends, lanthanum has the largest atomic radius of the lanthanides, hence, it is the most reactive among them, tarnishing slowly in air and burning readily to form lanthanum oxide, La2O3, which is almost as basic as calcium oxide
26.
Cerium
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Cerium is a soft, ductile, silvery-white metallic chemical element with symbol Ce and atomic number 58. Cerium tarnishes when exposed to air, and it is enough to be cut with a knife. Cerium is the element in the lanthanide series, and while it often shows the +3 state characteristic of the series. It is also considered to be one of the rare earth elements. Cerium has no role, and is not very toxic. It is the most common of the lanthanides, followed by neodymium, lanthanum and it is the 26th most abundant element, making up 66 ppm of the Earths crust, half as much as chlorine and five times as much as lead. The first of the lanthanides to be discovered, cerium was discovered in Bastnäs, Sweden by Jöns Jakob Berzelius and Wilhelm Hisinger in 1803 and it was first isolated by Carl Gustaf Mosander in 1839. Today, cerium and its compounds have a variety of uses, for example, cerium metal is used in ferrocerium lighters for its pyrophoric properties. Cerium is the element of the lanthanide series. In the periodic table, it appears between the lanthanides lanthanum to its left and praseodymium to its right, and above the actinide thorium and it is a ductile metal with a hardness similar to that of silver. Its 58 electrons are arranged in the configuration 4f15d16s2, of which the four electrons are valence electrons. The stable form below 726 °C to approximately room temperature is γ-cerium, the dhcp form of β-cerium is the equilibrium structure approximately from room temperature to −150 °C. The fcc α-cerium exists below about −150 °C, it has a density of 8.16 g/cm3, other solid phases occurring only at high pressures are shown on the phase diagram. Both γ and β forms are stable at room temperature. Cerium has an electronic structure. This gives rise to dual valency states, for example, a volume change of about 10% occurs when cerium is subjected to high pressures or low temperatures. It appears that the changes from about 3 to 4 when it is cooled or compressed. At lower temperatures the behavior of cerium is complicated by the rates of transformation
27.
Praseodymium
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Praseodymium is a chemical element with symbol Pr and atomic number 59. Praseodymium is a soft, silvery, malleable and ductile metal in the lanthanide group and it is valued for its magnetic, electrical, chemical, and optical properties. It is too reactive to be found in form. The element was named for the color of its primary oxide, in 1841, Swedish chemist Carl Gustav Mosander extracted a rare earth oxide residue he called didymium from a residue he called lanthana, in turn separated from cerium salts. In 1885, the Austrian chemist Baron Carl Auer von Welsbach separated didymium into two salts of different colors, which he named praseodymium and neodymium, the name praseodymium comes from the Greek prasinos, meaning green, and didymos, twin. Like most rare earth elements, praseodymium most readily forms trivalent Pr ions and these are yellow-green in water solution, and various shades of yellow-green when incorporated into glasses. Many of praseodymiums industrial uses involve its use to filter light from light sources. Praseodymium is a soft, silvery, malleable, and ductile metal in the lanthanide group, for this reason, praseodymium is usually stored under a light mineral oil or sealed in glass. Thus, in solution, only the +3 oxidation state is encountered. These positions vary slightly with the counter-ion and its formula is conventionally rendered as Pr6O11. Although praseodymium in the state is unknown, the existence of praseodymium in its +5 oxidation state under noble-gas matrix isolation conditions was reported in 2016. The species assigned to the +5 state were identified as +, its O2 and Ar adducts,38 radioisotopes have been characterized, with the most stable being praseodymium-143 with a half-life of 13.57 days and praseodymium-142 with a half-life of 19.12 hours. All of the radioactive isotopes have half-lives that are less than six hours. This element also has 15 nuclear isomers, with the longest-lived being praseodymium-138m, praseodymium-134m, the nuclei of nuclear isomers exist in a delicate equilibrium or metastability due to at least one nucleon having an excited energy state. The isotopes of praseodymium range in number from 121 to 159. The most common mode of 20 isotopes with mass numbers lower than the most abundant stable isotope, praseodymium-141 is β+ decay. The most common mode for 18 isotopes with mass numbers higher than praseodymium-141 is β− decay. In 1839 Mosander extracted an oxide he called lantana, which was the oxide of the newly discovered element lanthanum, the remaining less-basic rare earth retained the pinkish color, and Mosander called this remaining fraction didymium
28.
Neodymium
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Neodymium is a chemical element with symbol Nd and atomic number 60. It is a silvery metal that tarnishes in air. Neodymium was discovered in 1885 by the Austrian chemist Carl Auer von Welsbach and it is present in significant quantities in the ore minerals monazite and bastnäsite. Neodymium is not found naturally in form or unmixed with other lanthanides. Although neodymium is classed as an earth, it is a fairly common element, no rarer than cobalt, nickel, and copper. Most of the worlds commercial neodymium is mined in China, neodymium compounds were first commercially used as glass dyes in 1927, and they remain a popular additive in glasses. Some neodymium-doped glasses are used in lasers that emit infrared with wavelengths between 1047 and 1062 nanometers. These have been used in applications, such as experiments in inertial confinement fusion. Neodymium is also used various other substrate crystals, such as yttrium aluminum garnet in the Nd. This laser usually emits infrared at a wavelength of about 1064 nanometers, the Nd, YAG laser is one of the most commonly used solid-state lasers. Another important use of neodymium is as a component in the used to make high-strength neodymium magnets—powerful permanent magnets. Larger neodymium magnets are used in electric motors and generators. Neodymium, a rare metal, was present in the classical mischmetal at a concentration of about 18%. Metallic neodymium has a bright, silvery luster, but as one of the more reactive lanthanide rare-earth metals. The oxide layer forms then peels off, exposing the metal to further oxidation, thus, a centimeter-sized sample of neodymium completely oxidizes within a year. Neodymium commonly exists in two forms, with a transformation from a double hexagonal to a body-centered cubic structure taking place at about 863 °C. Naturally occurring neodymium is a mixture of five stable isotopes, 142Nd, 143Nd, 145Nd, 146Nd and 148Nd, with 142Nd being the most abundant, and two radioisotopes, 144Nd and 150Nd. In all,31 radioisotopes of neodymium have been detected as of 2010, with the most stable radioisotopes being the naturally occurring ones, 144Nd and 150Nd
29.
Promethium
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Promethium, originally prometheum, is a chemical element with the symbol Pm and atomic number 61. All of its isotopes are radioactive, it is one of two such elements that are followed in the periodic table by elements with stable forms, a distinction shared with technetium. Chemically, promethium is a lanthanide, which forms salts when combined with other elements, promethium shows only one stable oxidation state of +3, however, a few +2 compounds may exist. In 1926, an Italian and an American group claimed to have isolated a sample of element 61, promethium was first produced and characterized at Oak Ridge National Laboratory in 1945 by the separation and analysis of the fission products of uranium fuel irradiated in a graphite reactor. However, a sample of the metal was only in 1963. There are two sources for natural promethium, rare decays of natural europium-151, and uranium. Because natural promethium is exceedingly scarce, it is synthesized by bombarding uranium-235 with thermal neutrons to produce promethium-147. A promethium atom has 61 electrons, arranged in the configuration 4f56s2, in forming compounds, the atom loses its two outermost electrons and one of the 4f-electrons, which belongs to an open subshell. The elements atomic radius is the third largest among all the lanthanides but is slightly greater than those of the neighboring elements. It is the exception to the general trend of the contraction of the atoms with increase of atomic radius that is not caused by the filled 4f-subshell. Many properties of promethium rely on its position among lanthanides and are intermediate between those of neodymium and samarium, promethium has a double hexagonal close packed structure and a hardness of 63 kg/mm2. This low-temperature alpha form converts into a beta, body-centered cubic phase upon heating to 890 °C, promethium belongs to the cerium group of lanthanides and is chemically very similar to the neighboring elements. Because of its instability, chemical studies of promethium are incomplete, even though a few compounds have been synthesized, they are not fully studied, in general, they tend to be pink or red in color. Treatment of acidic solutions containing Pm3+ ions with ammonia results in a gelatinous light-brown sediment of hydroxide, Pm3, when dissolved in hydrochloric acid, a water-soluble yellow salt, PmCl3, is produced, similarly, when dissolved in nitric acid, a nitrate results, Pm3. The latter is also well-soluble, when dried, it forms pink crystals, the electron configuration for Pm3+ is 4f4, and the color of the ion is pink. The ground state term symbol is 5I4, the sulfate is slightly soluble, like the other cerium group sulfates. Cell parameters have been calculated for its octahydrate, they lead to conclusion that the density of Pm23·8 H2O is 2.86 g/cm3, the oxalate, Pm23·10 H2O, has the lowest solubility of all lanthanide oxalates. Unlike the nitrate, the oxide is similar to the corresponding samarium salt, as-synthesized, e. g. by heating the oxalate, it is a white or lavender-colored powder with disordered structure
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Samarium
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Samarium is a chemical element with symbol Sm and atomic number 62. It is a moderately hard silvery metal that readily oxidizes in air, being a typical member of the lanthanide series, samarium usually assumes the oxidation state +3. Compounds of samarium are also known, most notably the monoxide SmO, monochalcogenides SmS, SmSe and SmTe, the last compound is a common reducing agent in chemical synthesis. Samarium has no significant biological role and is slightly toxic. Samarium was discovered in 1879 by the French chemist Paul Émile Lecoq de Boisbaudran, although classified as a rare earth element, samarium is the 40th most abundant element in the Earths crust and is more common than such metals as tin. These minerals are found in China, the United States, Brazil, India, Sri Lanka and Australia, China is by far the world leader in samarium mining. The radioactive isotope samarium-153 is the component of the drug samarium lexidronam. Another isotope, samarium-149, is a neutron absorber and is therefore added to the control rods of nuclear reactors. It is also formed as a product during the reactor operation and is one of the important factors considered in the reactor design. Other applications of samarium include catalysis of chemical reactions, radioactive dating, Samarium is a rare earth metal having a hardness and density similar to those of zinc. With the boiling point of 1794 °C, samarium is the third most volatile lanthanide after ytterbium and europium, at ambient conditions, samarium normally assumes a rhombohedral structure. Upon heating to 731 °C, its crystal symmetry changes into hexagonally close-packed, further heating to 922 °C transforms the metal into a body-centered cubic phase. Heating to 300 °C combined with compression to 40 kbar results in a double-hexagonally close-packed structure, applying higher pressure of the order of hundreds or thousands of kilobars induces a series of phase transformations, in particular with a tetragonal phase appearing at about 900 kbar. Also, thin films of samarium obtained by vapor deposition may contain the hcp or dhcp phases at ambient conditions, Samarium are paramagnetic at room temperature. Their corresponding effective magnetic moments, below 2µB, are the 3rd lowest among the lanthanides after lanthanum and lutetium, the metal transforms to an antiferromagnetic state upon cooling to 14.8 K. Individual samarium atoms can be isolated by encapsulating them into fullerene molecules and they can also be doped between the C60 molecules in the fullerene solid, rendering it superconductive at temperatures below 8 K. Freshly prepared samarium has a silvery luster, in air, it slowly oxidizes at room temperature and spontaneously ignites at 150 °C. Even when stored under oil, samarium gradually oxidizes and develops a grayish-yellow powder of the oxide-hydroxide mixture at the surface
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Europium
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Europium is a chemical element with symbol Eu and atomic number 63. It was isolated in 1901 and is named after the continent of Europe and it is a moderately hard, silvery metal which readily oxidizes in air and water. Being a typical member of the series, europium usually assumes the oxidation state +3. All europium compounds with oxidation state +2 are slightly reducing, Europium has no significant biological role and is relatively non-toxic compared to other heavy metals. Most applications of europium exploit the phosphorescence of europium compounds, Europium is one of the least abundant elements in the universe, only about 5×10−8% of all matter in the universe is europium. Europium is a metal with a hardness similar to that of lead. It crystallizes in a cubic lattice. Some properties of europium are strongly influenced by its half-filled electron shell, Europium has the second lowest melting point and the lowest density of all lanthanides. Europium becomes a superconductor when it is cooled below 1.8 K and this is because europium is divalent in the metallic state, and is converted into the trivalent state by the applied pressure. In the divalent state, the local magnetic moment suppresses the superconductivity. Europium is the most reactive rare earth element and it rapidly oxidizes in air, so that bulk oxidation of a centimeter-sized sample occurs within several days. This behavior is unusual to most lanthanides, which almost exclusively form compounds with a state of +3. The +2 state has an electron configuration 4f7 because the half-filled f-shell gives more stability, in terms of size and coordination number, europium and barium are similar. For example, the sulfates of both barium and europium are also highly insoluble in water, divalent europium is a mild reducing agent, oxidizing in air to form Eu compounds. In anaerobic, and particularly geothermal conditions, the divalent form is sufficiently stable that it tends to be incorporated into minerals of calcium and the other alkaline earths. This ion-exchange process is the basis of the europium anomaly. Bastnäsite tends to show less of a negative europium anomaly than does monazite, the development of easy methods to separate divalent europium from the other lanthanides made europium accessible even when present in low concentration, as it usually is. Naturally occurring europium is composed of 2 isotopes, 151Eu and 153Eu, while 153Eu is stable, 151Eu was recently found to be unstable to alpha decay with half-life of 5+11 −3×1018 years, giving about 1 alpha decay per two minutes in every kilogram of natural europium
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Lutetium
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Lutetium is a chemical element with symbol Lu and atomic number 71. It is a white metal, which resists corrosion in dry air. Lutetium is the last element in the series, and it is traditionally counted among the rare earths. Lutetium is sometimes considered the first element of the 6th-period transition metals, Lutetium was independently discovered in 1907 by French scientist Georges Urbain, Austrian mineralogist Baron Carl Auer von Welsbach, and American chemist Charles James. All of these researchers found lutetium as an impurity in the mineral ytterbia and he chose the name lutecium for the new element, but in 1949 the spelling of element 71 was changed to lutetium. Lutetium is not an abundant element, although it is significantly more common than silver in the earths crust. Lutetium-176 is a relatively abundant radioactive isotope with a half-life of about 38 billion years used to determine the age of meteorites, Lutetium usually occurs in association with the element yttrium and is sometimes used in metal alloys and as a catalyst in various chemical reactions. 177Lu-DOTA-TATE is used for therapy on neuroendocrine tumours. Lutetium has the highest Brinell hardness of any lanthanide, at 890–1300 MPa, a lutetium atom has 71 electrons, arranged in the configuration 4f145d16s2. When entering a chemical reaction, the atom loses its two outermost electrons and the single 5d-electron. The lutetium atom is the smallest among the lanthanide atoms, due to the contraction, and as a result lutetium has the highest density, melting point. Lutetiums compounds always contain the element in the oxidation state +3, aqueous solutions of most lutetium salts are colorless and form white crystalline solids upon drying, with the common exception of the iodide. The soluble salts, such as nitrate, sulfate and acetate form hydrates upon crystallization, the oxide, hydroxide, fluoride, carbonate, phosphate and oxalate are insoluble in water. Lutetium metal is slightly unstable in air at standard conditions, the resulting compound is known to absorb water and carbon dioxide, and may be used to remove vapors of these compounds from closed atmospheres. Similar observations are made during reaction between lutetium and water, lutetium hydroxide is formed in the reaction, Lutetium metal is known to react with the four lightest halogens to form trihalides, all of them are soluble in water. 2 Lu +3 H2SO4 →2 Lu3+ +3 SO2–4 +3 H2↑ Lutetium occurs on the Earth in form of two isotopes, lutetium-175 and lutetium-176, out of these two, only the former is stable, making the element monoisotopic. The latter one, lutetium-176, decays via beta decay with a half-life of 3. 78×1010 years, all of the remaining radioactive isotopes have half-lives that are less than 9 days, and the majority of these have half-lives that are less than half an hour. Isotopes lighter than the stable lutetium-175 decay via electron capture, with alpha and positron emission
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International Standard Book Number
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The International Standard Book Number is a unique numeric commercial book identifier. An ISBN is assigned to each edition and variation of a book, for example, an e-book, a paperback and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January 2007, the method of assigning an ISBN is nation-based and varies from country to country, often depending on how large the publishing industry is within a country. The initial ISBN configuration of recognition was generated in 1967 based upon the 9-digit Standard Book Numbering created in 1966, the 10-digit ISBN format was developed by the International Organization for Standardization and was published in 1970 as international standard ISO2108. Occasionally, a book may appear without a printed ISBN if it is printed privately or the author does not follow the usual ISBN procedure, however, this can be rectified later. Another identifier, the International Standard Serial Number, identifies periodical publications such as magazines, the ISBN configuration of recognition was generated in 1967 in the United Kingdom by David Whitaker and in 1968 in the US by Emery Koltay. The 10-digit ISBN format was developed by the International Organization for Standardization and was published in 1970 as international standard ISO2108, the United Kingdom continued to use the 9-digit SBN code until 1974. The ISO on-line facility only refers back to 1978, an SBN may be converted to an ISBN by prefixing the digit 0. For example, the edition of Mr. J. G. Reeder Returns, published by Hodder in 1965, has SBN340013818 -340 indicating the publisher,01381 their serial number. This can be converted to ISBN 0-340-01381-8, the check digit does not need to be re-calculated, since 1 January 2007, ISBNs have contained 13 digits, a format that is compatible with Bookland European Article Number EAN-13s. An ISBN is assigned to each edition and variation of a book, for example, an ebook, a paperback, and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January 2007, a 13-digit ISBN can be separated into its parts, and when this is done it is customary to separate the parts with hyphens or spaces. Separating the parts of a 10-digit ISBN is also done with either hyphens or spaces, figuring out how to correctly separate a given ISBN number is complicated, because most of the parts do not use a fixed number of digits. ISBN issuance is country-specific, in that ISBNs are issued by the ISBN registration agency that is responsible for country or territory regardless of the publication language. Some ISBN registration agencies are based in national libraries or within ministries of culture, in other cases, the ISBN registration service is provided by organisations such as bibliographic data providers that are not government funded. In Canada, ISBNs are issued at no cost with the purpose of encouraging Canadian culture. In the United Kingdom, United States, and some countries, where the service is provided by non-government-funded organisations. Australia, ISBNs are issued by the library services agency Thorpe-Bowker
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Geology
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Geology is an earth science concerned with the solid Earth, the rocks of which it is composed, and the processes by which they change over time. Geology can also refer generally to the study of the features of any terrestrial planet. Geology gives insight into the history of the Earth by providing the evidence for plate tectonics, the evolutionary history of life. Geology also plays a role in engineering and is a major academic discipline. The majority of data comes from research on solid Earth materials. These typically fall into one of two categories, rock and unconsolidated material, the majority of research in geology is associated with the study of rock, as rock provides the primary record of the majority of the geologic history of the Earth. There are three types of rock, igneous, sedimentary, and metamorphic. The rock cycle is an important concept in geology which illustrates the relationships between three types of rock, and magma. When a rock crystallizes from melt, it is an igneous rock, the sedimentary rock can then be subsequently turned into a metamorphic rock due to heat and pressure and is then weathered, eroded, deposited, and lithified, ultimately becoming a sedimentary rock. Sedimentary rock may also be re-eroded and redeposited, and metamorphic rock may also undergo additional metamorphism, all three types of rocks may be re-melted, when this happens, a new magma is formed, from which an igneous rock may once again crystallize. Geologists also study unlithified material which typically comes from more recent deposits and these materials are superficial deposits which lie above the bedrock. Because of this, the study of material is often known as Quaternary geology. This includes the study of sediment and soils, including studies in geomorphology, sedimentology and this theory is supported by several types of observations, including seafloor spreading, and the global distribution of mountain terrain and seismicity. This coupling between rigid plates moving on the surface of the Earth and the mantle is called plate tectonics. The development of plate tectonics provided a basis for many observations of the solid Earth. Long linear regions of geologic features could be explained as plate boundaries, mid-ocean ridges, high regions on the seafloor where hydrothermal vents and volcanoes exist, were explained as divergent boundaries, where two plates move apart. Arcs of volcanoes and earthquakes were explained as convergent boundaries, where one plate subducts under another, transform boundaries, such as the San Andreas Fault system, resulted in widespread powerful earthquakes. Plate tectonics also provided a mechanism for Alfred Wegeners theory of continental drift and they also provided a driving force for crustal deformation, and a new setting for the observations of structural geology
