Dysprosium | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Pronunciation | /dɪsˈproʊziəm/ | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
Appearance | silvery white | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
Standard atomic weight Ar°(Dy) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Dysprosium in the periodic table | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Atomic number (Z) | 66 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
Group | f-block groups (no number) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
Period | period 6 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
Block | f-block | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
Electron configuration | [ Xe ] 4f10 6s2 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
Electrons per shell | 2, 8, 18, 28, 8, 2 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
Physical properties | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Phase at STP | solid | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
Melting point | 1680 K (1407 °C,2565 °F) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
Boiling point | 2840 K(2562 °C,4653 °F) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
Density (at 20° C) | 8.550 g/cm3 [3] | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
when liquid (at m.p.) | 8.37 g/cm3 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
Heat of fusion | 11.06 kJ/mol | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
Heat of vaporization | 280 kJ/mol | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
Molar heat capacity | 27.7 J/(mol·K) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
Vapor pressure
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Atomic properties | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Oxidation states | 0, [4] +1, +2, +3, +4 (a weakly basic oxide) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
Electronegativity | Pauling scale: 1.22 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
Ionization energies |
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Atomic radius | empirical:178 pm | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
Covalent radius | 192±7 pm | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
Spectral lines of dysprosium | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Other properties | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Natural occurrence | primordial | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
Crystal structure | hexagonal close-packed (hcp)(hP2) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
Lattice constants | a = 359.16 pm c = 565.01 pm (at 20 °C) [3] | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
Thermal expansion | poly: 9.9 µm/(m⋅K)(r.t.) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
Thermal conductivity | 10.7 W/(m⋅K) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
Electrical resistivity | α, poly: 926 nΩ⋅m(r.t.) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
Magnetic ordering | paramagnetic at 300 K | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
Molar magnetic susceptibility | +103500×10−6 cm3/mol(293.2 K) [5] | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
Young's modulus | 61.4 GPa | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
Shear modulus | 24.7 GPa | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
Bulk modulus | 40.5 GPa | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
Speed of sound thin rod | 2710 m/s(at 20 °C) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
Poisson ratio | 0.247 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
Vickers hardness | 410–550 MPa | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
Brinell hardness | 500–1050 MPa | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
CAS Number | 7429-91-6 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
History | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Discovery | Lecoq de Boisbaudran (1886) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
First isolation | Georges Urbain (1905) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
Isotopes of dysprosium | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Dysprosium is a chemical element; it has symbol Dy and atomic number 66. It is a rare-earth element in the lanthanide series with a metallic silver luster. Dysprosium is never found in nature as a free element, though, like other lanthanides, it is found in various minerals, such as xenotime. Naturally occurring dysprosium is composed of seven isotopes, the most abundant of which is 164Dy.
Dysprosium was first identified in 1886 by Paul Émile Lecoq de Boisbaudran, but it was not isolated in pure form until the development of ion-exchange techniques in the 1950s. Dysprosium has relatively few applications where it cannot be replaced by other chemical elements. It is used for its high thermal neutron absorption cross-section in making control rods in nuclear reactors, for its high magnetic susceptibility (χv ≈ 5.44×10−3) in data-storage applications, and as a component of Terfenol-D (a magnetostrictive material). Soluble dysprosium salts are mildly toxic, while the insoluble salts are considered non-toxic.
Dysprosium is a rare-earth element and has a metallic, bright silver luster. It is quite soft and can be machined without sparking if overheating is avoided. Dysprosium's physical characteristics can be greatly affected by even small amounts of impurities. [8]
Dysprosium and holmium have the highest magnetic strengths of the elements, [9] especially at low temperatures. [10] Dysprosium has a simple ferromagnetic ordering at temperatures below its Curie temperature of 90.5 K (−182.7 °C), at which point it undergoes a first-order phase transition from the orthorhombic crystal structure to hexagonal close-packed (hcp). [3] It then has a helical antiferromagnetic state, in which all of the atomic magnetic moments in a particular basal plane layer are parallel and oriented at a fixed angle to the moments of adjacent layers. This unusual antiferromagnetism transforms into a disordered (paramagnetic) state at 179 K (−94 °C). [11] It transforms from the hcp phase to the body-centered cubic phase at 1,654 K (1,381 °C). [3]
Dysprosium metal retains its luster in dry air but it will tarnish slowly in moist air, and it burns readily to form dysprosium(III) oxide:
Dysprosium is quite electropositive and reacts slowly with cold water (and quickly with hot water) to form dysprosium hydroxide:
Dysprosium hydroxide decomposes to form DyO(OH) at elevated temperatures, which then decomposes again to dysprosium(III) oxide. [12]
Dysprosium metal vigorously reacts with all the halogens at above 200 °C:[ citation needed ]
Dysprosium dissolves readily in dilute sulfuric acid to form solutions containing the yellow Dy(III) ions, which exist as a [Dy(OH2)9]3+ complex: [13]
The resulting compound, dysprosium(III) sulfate, is noticeably paramagnetic.
Dysprosium halides, such as DyF3 and DyBr3, tend to take on a yellow color. Dysprosium oxide, also known as dysprosia, is a white powder that is highly magnetic, more so than iron oxide. [10]
Dysprosium combines with various non-metals at high temperatures to form binary compounds with varying composition and oxidation states +3 and sometimes +2, such as DyN, DyP, DyH2 and DyH3; DyS, DyS2, Dy2S3 and Dy5S7; DyB2, DyB4, DyB6 and DyB12, as well as Dy3C and Dy2C3. [14]
Dysprosium carbonate, Dy2(CO3)3, and dysprosium sulfate, Dy2(SO4)3, result from similar reactions. [15] Most dysprosium compounds are soluble in water, though dysprosium carbonate tetrahydrate (Dy2(CO3)3·4H2O) and dysprosium oxalate decahydrate (Dy2(C2O4)3·10H2O) are both insoluble in water. [16] [17] Two of the most abundant dysprosium carbonates, Dy2(CO3)3·2–3H2O (similar to the mineral tengerite-(Y)), and DyCO3(OH) (similar to minerals kozoite-(La) and kozoite-(Nd)), are known to form via a poorly ordered (amorphous) precursor phase with a formula of Dy2(CO3)3·4H2O. This amorphous precursor consists of highly hydrated spherical nanoparticles of 10–20 nm diameter that are exceptionally stable under dry treatment at ambient and high temperatures. [18]
Dysprosium forms several intermetallics, including the dysprosium stannides. [19]
Naturally occurring dysprosium is composed of seven isotopes: 156Dy, 158Dy, 160Dy, 161Dy, 162Dy, 163Dy, and 164Dy. These are all considered stable, although only the last two are theoretically stable: the others can theoretically undergo alpha decay. Of the naturally occurring isotopes, 164Dy is the most abundant at 28%, followed by 162Dy at 26%. The least abundant is 156Dy at 0.06%. [20] Dysprosium is the heaviest element to have isotopes that are predicted to be stable rather than observationally stable isotopes that are predicted to be radioactive.
Twenty-nine radioisotopes have been synthesized, ranging in atomic mass from 138 to 173. The most stable of these is 154Dy, with a half-life of approximately 3×106 years, followed by 159Dy with a half-life of 144.4 days. The least stable is 138Dy, with a half-life of 200 ms. As a general rule, isotopes that are lighter than the stable isotopes tend to decay primarily by β+ decay, while those that are heavier tend to decay by β− decay. However, 154Dy decays primarily by alpha decay, and 152Dy and 159Dy decay primarily by electron capture. [20] Dysprosium also has at least 11 metastable isomers, ranging in atomic mass from 140 to 165. The most stable of these is 165mDy, which has a half-life of 1.257 minutes. 149Dy has two metastable isomers, the second of which, 149m2Dy, has a half-life of 28 ns. [20]
In 1878, erbium ores were found to contain the oxides of holmium and thulium. French chemist Paul Émile Lecoq de Boisbaudran, while working with holmium oxide, separated dysprosium oxide from it in Paris in 1886. [21] [22] His procedure for isolating the dysprosium involved dissolving dysprosium oxide in acid, then adding ammonia to precipitate the hydroxide. He was only able to isolate dysprosium from its oxide after more than 30 attempts at his procedure. On succeeding, he named the element dysprosium from the Greek dysprositos (δυσπρόσιτος), meaning "hard to get". The element was not isolated in relatively pure form until after the development of ion exchange techniques by Frank Spedding at Iowa State University in the early 1950s. [9] [23]
Due to its role in permanent magnets used for wind turbines, it has been argued[ by whom? ] that dysprosium will be one of the main objects of geopolitical competition in a world running on renewable energy. But this perspective has been criticised for failing to recognise that most wind turbines do not use permanent magnets and for underestimating the power of economic incentives for expanded production. [24] [25]
In 2021, Dy was turned into a 2-dimensional supersolid quantum gas. [26]
While dysprosium is never encountered as a free element, it is found in many minerals, including xenotime, fergusonite, gadolinite, euxenite, polycrase, blomstrandine, monazite and bastnäsite, often with erbium and holmium or other rare earth elements. No dysprosium-dominant mineral (that is, with dysprosium prevailing over other rare earths in the composition) has yet been found. [27]
In the high-yttrium version of these, dysprosium happens to be the most abundant of the heavy lanthanides, comprising up to 7–8% of the concentrate (as compared to about 65% for yttrium). [28] [29] The concentration of Dy in the Earth's crust is about 5.2 mg/kg and in sea water 0.9 ng/L. [14]
Dysprosium is obtained primarily from monazite sand, a mixture of various phosphates. The metal is obtained as a by-product in the commercial extraction of yttrium. In isolating dysprosium, most of the unwanted metals can be removed magnetically or by a flotation process. Dysprosium can then be separated from other rare earth metals by an ion exchange displacement process. The resulting dysprosium ions can then react with either fluorine or chlorine to form dysprosium fluoride, DyF3, or dysprosium chloride, DyCl3. These compounds can be reduced using either calcium or lithium metals in the following reactions: [15]
The components are placed in a tantalum crucible and fired in a helium atmosphere. As the reaction progresses, the resulting halide compounds and molten dysprosium separate due to differences in density. When the mixture cools, the dysprosium can be cut away from the impurities. [15]
About 100 tonnes of dysprosium are produced worldwide each year, [30] with 99% of that total produced in China. [31] Dysprosium prices have climbed nearly twentyfold, from $7 per pound in 2003, to $130 a pound in late 2010. [31] The price increased to $1,400/kg in 2011 but fell to $240 in 2015, largely due to illegal production in China which circumvented government restrictions. [32]
Currently, most dysprosium is being obtained from the ion-adsorption clay ores of southern China. [33] As of November 2018 [update] the Browns Range Project pilot plant, 160 km south east of Halls Creek, Western Australia, is producing 50 tonnes (49 long tons) per annum. [34] [35]
According to the United States Department of Energy, the wide range of its current and projected uses, together with the lack of any immediately suitable replacement, makes dysprosium the single most critical element for emerging clean energy technologies; even their most conservative projections predicted a shortfall of dysprosium before 2015. [36] As of late 2015, there is a nascent rare earth (including dysprosium) extraction industry in Australia. [37]
Dysprosium is used, in conjunction with vanadium and other elements, in making laser materials and commercial lighting. Because of dysprosium's high thermal-neutron absorption cross-section, dysprosium-oxide–nickel cermets are used in neutron-absorbing control rods in nuclear reactors. [9] [38] Dysprosium–cadmium chalcogenides are sources of infrared radiation, which is useful for studying chemical reactions. [8] Because dysprosium and its compounds are highly susceptible to magnetization, they are employed in various data-storage applications, such as in hard disks. [39] Dysprosium is increasingly in demand for the permanent magnets used in electric-car motors and wind-turbine generators. [40]
Neodymium–iron–boron magnets can have up to 6% of the neodymium substituted by dysprosium [41] to raise the coercivity for demanding applications, such as drive motors for electric vehicles and generators for wind turbines. This substitution would require up to 100 grams of dysprosium per electric car produced. Based on Toyota's projected 2 million units per year, the use of dysprosium in applications such as this would quickly exhaust its available supply. [42] The dysprosium substitution may also be useful in other applications because it improves the corrosion resistance of the magnets. [43]
Dysprosium is one of the components of Terfenol-D, along with iron and terbium. Terfenol-D has the highest room-temperature magnetostriction of any known material, [44] which is employed in transducers, wide-band mechanical resonators, [45] and high-precision liquid-fuel injectors. [46]
Dysprosium is used in dosimeters for measuring ionizing radiation. [47] Crystals of calcium sulfate or calcium fluoride are doped with dysprosium. When these crystals are exposed to radiation, the dysprosium atoms become excited and luminescent. The luminescence can be measured to determine the degree of exposure to which the dosimeter has been subjected. [9]
Nanofibers of dysprosium compounds have high strength and a large surface area. Therefore, they can be used to reinforce other materials and act as a catalyst. Fibers of dysprosium oxide fluoride can be produced by heating an aqueous solution of DyBr3 and NaF to 450 °C at 450 bars for 17 hours. This material is remarkably robust, surviving over 100 hours in various aqueous solutions at temperatures exceeding 400 °C without redissolving or aggregating. [48] [49] [50] Additionally, dysprosium has been used to create a two dimensional supersolid in a laboratory environment. Supersolids are expected to exhibit unusual properties, including superfluidity. [51]
Dysprosium iodide and dysprosium bromide are used in high-intensity metal-halide lamps. These compounds dissociate near the hot center of the lamp, releasing isolated dysprosium atoms. The latter re-emit light in the green and red part of the spectrum, thereby effectively producing bright light. [9] [52]
Several paramagnetic crystal salts of dysprosium (dysprosium gallium garnet, DGG; dysprosium aluminium garnet, DAG; dysprosium iron garnet, DyIG) are used in adiabatic demagnetization refrigerators. [53] [54]
The trivalent dysprosium ion (Dy3+) has been studied due to its downshifting luminescence properties. Dy-doped yttrium aluminium garnet (Dy:YAG) excited in the ultraviolet region of the electromagnetic spectrum results in the emission of photons of longer wavelength in the visible region. This idea is the basis for a new generation of UV-pumped white light-emitting diodes. [55]
The stable isotopes of dysprosium have been laser cooled and confined in magneto-optical traps [56] for quantum physics experiments. The first Bose and Fermi quantum degenerate gases of an open shell lanthanide were created with dysprosium. [57] [58] Because dysprosium is highly magnetic—indeed it is the most magnetic fermionic element and nearly tied with terbium for most magnetic bosonic atom [59] —such gases serve as the basis for quantum simulation with strongly dipolar atoms. [60]
Due to its strong magnetic properties, Dysprosium alloys are used in the marine industry's sound navigation and ranging (SONAR) system. [61] [62] The inclusion of dysprosium alloys in the design of SONAR transducers and receivers can improve sensitivity and accuracy by providing more stable and efficient magnetic fields. [63]
Like many powders, dysprosium powder may present an explosion hazard when mixed with air and when an ignition source is present. Thin foils of the substance can also be ignited by sparks or by static electricity. Dysprosium fires cannot be extinguished with water. It can react with water to produce flammable hydrogen gas. [64] Dysprosium chloride fires can be extinguished with water. [65] Dysprosium fluoride and dysprosium oxide are non-flammable. [66] [67] Dysprosium nitrate, Dy(NO3)3, is a strong oxidizing agent and readily ignites on contact with organic substances. [10]
Soluble dysprosium salts, such as dysprosium chloride and dysprosium nitrate are mildly toxic when ingested. Based on the toxicity of dysprosium chloride to mice, it is estimated that the ingestion of 500 grams or more could be fatal to a human (c.f. lethal dose of 300 grams of common table salt for a 100 kilogram human). The insoluble salts are non-toxic. [9]
Berkelium is a synthetic chemical element; it has symbol Bk and atomic number 97. It is a member of the actinide and transuranium element series. It is named after the city of Berkeley, California, the location of the Lawrence Berkeley National Laboratory where it was discovered in December 1949. Berkelium was the fifth transuranium element discovered after neptunium, plutonium, curium and americium.
Europium is a chemical element; it has symbol Eu and atomic number 63. Europium is a silvery-white metal of the lanthanide series that reacts readily with air to form a dark oxide coating. It is the most chemically reactive, least dense, and softest of the lanthanide elements. It is soft enough to be cut with a knife. Europium was isolated in 1901 and named after the continent of Europe. Europium usually assumes the oxidation state +3, like other members of the lanthanide series, but compounds having oxidation state +2 are also common. 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 rarest of the rare-earth elements on Earth.
Erbium is a chemical element; it has symbol Er and atomic number 68. A silvery-white solid metal when artificially isolated, natural erbium is always found in chemical combination with other elements. It is a lanthanide, a rare-earth element, originally found in the gadolinite mine in Ytterby, Sweden, which is the source of the element's name.
Gadolinium is a chemical element; it has symbol Gd and atomic number 64. Gadolinium is a silvery-white metal when oxidation is removed. It is a malleable and ductile rare-earth element. Gadolinium reacts with atmospheric oxygen or moisture slowly to form a black coating. Gadolinium below its Curie point of 20 °C (68 °F) is ferromagnetic, with an attraction to a magnetic field higher than that of nickel. Above this temperature it is the most paramagnetic element. It is found in nature only in an oxidized form. When separated, it usually has impurities of the other rare earths because of their similar chemical properties.
Holmium is a chemical element; it has symbol Ho and atomic number 67. It is a rare-earth element and the eleventh member of the lanthanide series. It is a relatively soft, silvery, fairly corrosion-resistant and malleable metal. Like many other lanthanides, holmium is too reactive to be found in native form, as pure holmium slowly forms a yellowish oxide coating when exposed to air. When isolated, holmium is relatively stable in dry air at room temperature. However, it reacts with water and corrodes readily, and also burns in air when heated.
Lanthanum is a chemical element; it has symbol La and atomic number 57. It is a soft, ductile, silvery-white metal that tarnishes slowly when exposed to air. It is the eponym of the lanthanide series, a group of 15 similar elements between lanthanum and lutetium in the periodic table, of which lanthanum is the first and the prototype. Lanthanum is traditionally counted among the rare earth elements. Like most other rare earth elements, its usual oxidation state is +3, although some compounds are known with an oxidation state of +2. Lanthanum has no biological role in humans but is essential to some bacteria. It is not particularly toxic to humans but does show some antimicrobial activity.
Lutetium is a chemical element; it has symbol Lu and atomic number 71. It is a silvery white metal, which resists corrosion in dry air, but not in moist air. Lutetium is the last element in the lanthanide series, and it is traditionally counted among the rare earth elements; it can also be classified as the first element of the 6th-period transition metals.
The lanthanide or lanthanoid series of chemical elements comprises at least the 14 metallic chemical elements with atomic numbers 57–70, from lanthanum through ytterbium. In the periodic table, they fill the 4f orbitals. Lutetium is also sometimes considered a lanthanide, despite being a d-block element and a transition metal.
Neodymium is a chemical element; it has symbol Nd and atomic number 60. It is the fourth member of the lanthanide series and is considered to be one of the rare-earth metals. It is a hard, slightly malleable, silvery metal that quickly tarnishes in air and moisture. When oxidized, neodymium reacts quickly producing pink, purple/blue and yellow compounds in the +2, +3 and +4 oxidation states. It is generally regarded as having one of the most complex spectra of the elements. Neodymium was discovered in 1885 by the Austrian chemist Carl Auer von Welsbach, who also discovered praseodymium. It is present in significant quantities in the minerals monazite and bastnäsite. Neodymium is not found naturally in metallic form or unmixed with other lanthanides, and it is usually refined for general use. Neodymium is fairly common—about as common as cobalt, nickel, or copper—and is widely distributed in the Earth's crust. Most of the world's commercial neodymium is mined in China, as is the case with many other rare-earth metals.
Neptunium is a chemical element; it has symbol Np and atomic number 93. A radioactive actinide metal, neptunium is the first transuranic element. It is named after Neptune, the planet beyond Uranus in the Solar System, which uranium is named after. A neptunium atom has 93 protons and 93 electrons, of which seven are valence electrons. Neptunium metal is silvery and tarnishes when exposed to air. The element occurs in three allotropic forms and it normally exhibits five oxidation states, ranging from +3 to +7. Like all actinides, it is radioactive, poisonous, pyrophoric, and capable of accumulating in bones, which makes the handling of neptunium dangerous.
Promethium is a chemical element with symbol Pm and atomic number 61. All of its isotopes are radioactive; it is extremely rare, with only about 500–600 grams naturally occurring in the Earth's crust at any given time. Promethium is one of the only two radioactive elements that are followed in the periodic table by elements with stable forms, the other being technetium. Chemically, promethium is a lanthanide. Promethium shows only one stable oxidation state of +3.
Scandium is a chemical element with the symbol Sc and atomic number 21. It is a silvery-white metallic d-block element. Historically, it has been classified as a rare-earth element, together with yttrium and the lanthanides. It was discovered in 1879 by spectral analysis of the minerals euxenite and gadolinite from Scandinavia.
Terbium is a chemical element; it has the symbol Tb and atomic number 65. It is a silvery-white, rare earth metal that is malleable and ductile. The ninth member of the lanthanide series, terbium is a fairly electropositive metal that reacts with water, evolving hydrogen gas. Terbium is never found in nature as a free element, but it is contained in many minerals, including cerite, gadolinite, monazite, xenotime and euxenite.
Thulium is a chemical element; it has symbol Tm and atomic number 69. It is the thirteenth element in the lanthanide series of metals. It is the second-least abundant lanthanide in the Earth's crust, after radioactively unstable promethium. It is an easily workable metal with a bright silvery-gray luster. It is fairly soft and slowly tarnishes in air. Despite its high price and rarity, thulium is used as a dopant in solid-state lasers, and as the radiation source in some portable X-ray devices. It has no significant biological role and is not particularly toxic.
Ytterbium is a chemical element; it has symbol Yb and atomic number 70. It is a metal, the fourteenth and penultimate element in the lanthanide series, which is the basis of the relative stability of its +2 oxidation state. Like the other lanthanides, its most common oxidation state is +3, as in its oxide, halides, and other compounds. In aqueous solution, like compounds of other late lanthanides, soluble ytterbium compounds form complexes with nine water molecules. Because of its closed-shell electron configuration, its density, melting point and boiling point are much lower than those of most other lanthanides.
Praseodymium is a chemical element; it has symbol Pr and the atomic number 59. It is the third member of the lanthanide series and is considered one of the rare-earth metals. It is a soft, silvery, malleable and ductile metal, valued for its magnetic, electrical, chemical, and optical properties. It is too reactive to be found in native form, and pure praseodymium metal slowly develops a green oxide coating when exposed to air.
Group 3 is the first group of transition metals in the periodic table. This group is closely related to the rare-earth elements. It contains the four elements scandium (Sc), yttrium (Y), lutetium (Lu), and lawrencium (Lr). The group is also called the scandium group or scandium family after its lightest member.
Yttrium is a chemical element; it has symbol Y and atomic number 39. It is a silvery-metallic transition metal chemically similar to the lanthanides and has often been classified as a "rare-earth element". Yttrium is almost always found in combination with lanthanide elements in rare-earth minerals and is never found in nature as a free element. 89Y is the only stable isotope and the only isotope found in the Earth's crust.
Cerium is a chemical element; it has symbol Ce and atomic number 58. It is a soft, ductile, and silvery-white metal that tarnishes when exposed to air. Cerium is the second element in the lanthanide series, and while it often shows the oxidation state of +3 characteristic of the series, it also has a stable +4 state that does not oxidize water. It is considered one of the rare-earth elements. Cerium has no known biological role in humans but is not particularly toxic, except with intense or continued exposure.
Terbium compounds are compounds formed by the lanthanide metal terbium (Tb). Terbium generally exhibits the +3 oxidation state in these compounds, such as in TbCl3, Tb(NO3)3 and Tb(CH3COO)3. Compounds with terbium in the +4 oxidation state are also known, such as TbO2 and BaTbF6. Terbium can also form compounds in the 0, +1 and +2 oxidation states.
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