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| Terbium | ||||||||||||||||||||||||||||
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| Pronunciation | /ˈtɜːrbiəm/ | |||||||||||||||||||||||||||
| Appearance | silvery white | |||||||||||||||||||||||||||
| Standard atomic weight Ar°(Tb) | ||||||||||||||||||||||||||||
| Terbium in the periodic table | ||||||||||||||||||||||||||||
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| Atomic number (Z) | 65 | |||||||||||||||||||||||||||
| Group | f-block groups (no number) | |||||||||||||||||||||||||||
| Period | period 6 | |||||||||||||||||||||||||||
| Block | f-block | |||||||||||||||||||||||||||
| Electron configuration | [Xe] 4f9 6s2 | |||||||||||||||||||||||||||
| Electrons per shell | 2, 8, 18, 27, 8, 2 | |||||||||||||||||||||||||||
| Physical properties | ||||||||||||||||||||||||||||
| Phase at STP | solid | |||||||||||||||||||||||||||
| Melting point | 1629 K (1356 °C, 2473 °F) | |||||||||||||||||||||||||||
| Boiling point | 3396 K (3123 °C, 5653 °F) | |||||||||||||||||||||||||||
| Density (at 20° C) | 8.229 g/cm3 [3] | |||||||||||||||||||||||||||
| when liquid (at m.p.) | 7.65 g/cm3 | |||||||||||||||||||||||||||
| Heat of fusion | 10.15 kJ/mol | |||||||||||||||||||||||||||
| Heat of vaporization | 391 kJ/mol | |||||||||||||||||||||||||||
| Molar heat capacity | 28.91 J/(mol·K) | |||||||||||||||||||||||||||
Vapor pressure
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| Atomic properties | ||||||||||||||||||||||||||||
| Oxidation states | common: +3 0,[4] +1,[5] +2,? +4[6] | |||||||||||||||||||||||||||
| Electronegativity | Pauling scale: 1.2 (?) | |||||||||||||||||||||||||||
| Ionization energies |
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| Atomic radius | empirical: 177 pm | |||||||||||||||||||||||||||
| Covalent radius | 194±5 pm | |||||||||||||||||||||||||||
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| Other properties | ||||||||||||||||||||||||||||
| Natural occurrence | primordial | |||||||||||||||||||||||||||
| Crystal structure | hexagonal close-packed (hcp) (hP2) | |||||||||||||||||||||||||||
| Lattice constants |  c = 569.66 pm (at 20 °C)[3] | |||||||||||||||||||||||||||
| Thermal expansion | at r.t. poly: 10.3 µm/(m⋅K) | |||||||||||||||||||||||||||
| Thermal conductivity | 11.1 W/(m⋅K) | |||||||||||||||||||||||||||
| Electrical resistivity | α, poly: 1.150 µΩ⋅m (at r.t.) | |||||||||||||||||||||||||||
| Magnetic ordering | paramagnetic at 300 K | |||||||||||||||||||||||||||
| Molar magnetic susceptibility | +146000×10−6 cm3/mol (273 K)[7] | |||||||||||||||||||||||||||
| Young's modulus | 55.7 GPa | |||||||||||||||||||||||||||
| Shear modulus | 22.1 GPa | |||||||||||||||||||||||||||
| Bulk modulus | 38.7 GPa | |||||||||||||||||||||||||||
| Speed of sound thin rod | 2620 m/s (at 20 °C) | |||||||||||||||||||||||||||
| Poisson ratio | 0.261 | |||||||||||||||||||||||||||
| Vickers hardness | 450–865 MPa | |||||||||||||||||||||||||||
| Brinell hardness | 675–1200 MPa | |||||||||||||||||||||||||||
| CAS Number | 7440-27-9 | |||||||||||||||||||||||||||
| History | ||||||||||||||||||||||||||||
| Naming | after Ytterby (Sweden), where it was mined | |||||||||||||||||||||||||||
| Discovery and first isolation | Carl Gustaf Mosander (1843) | |||||||||||||||||||||||||||
| Isotopes of terbium | ||||||||||||||||||||||||||||
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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.
Swedish chemist Carl Gustaf Mosander discovered terbium as a chemical element in 1843. He detected it as an impurity in yttrium oxide (Y2O3). Yttrium and terbium, as well as erbium and ytterbium, are named after the village of Ytterby in Sweden. Terbium was not isolated in pure form until the advent of ion exchange techniques.
Terbium is used to dope calcium fluoride, calcium tungstate and strontium molybdate in solid-state devices, and as a crystal stabilizer of fuel cells that operate at elevated temperatures. As a component of Terfenol-D (an alloy that expands and contracts when exposed to magnetic fields more than any other alloy), terbium is of use in actuators, in naval sonar systems and in sensors. Terbium is considered non-hazardous, though its biological role and toxicity has not been researched in depth.
Most of the world's terbium supply is used in green phosphors. Terbium oxide is used in fluorescent lamps and television and monitor cathode-ray tubes (CRTs). Terbium green phosphors are combined with divalent europium blue phosphors and trivalent europium red phosphors to provide trichromatic lighting technology, a high-efficiency white light used in indoor lighting.
- ^ "Standard Atomic Weights: Terbium". CIAAW. 2021.
- ^ Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (2022-05-04). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.
- ^ a b Arblaster, John W. (2018). Selected Values of the Crystallographic Properties of Elements. Materials Park, Ohio: ASM International. ISBN 978-1-62708-155-9.
- ^ Yttrium and all lanthanides except Ce and Pm have been observed in the oxidation state 0 in bis(1,3,5-tri-t-butylbenzene) complexes, see Cloke, F. Geoffrey N. (1993). "Zero Oxidation State Compounds of Scandium, Yttrium, and the Lanthanides". Chem. Soc. Rev. 22: 17–24. doi:10.1039/CS9932200017. and Arnold, Polly L.; Petrukhina, Marina A.; Bochenkov, Vladimir E.; Shabatina, Tatyana I.; Zagorskii, Vyacheslav V.; Cloke (2003-12-15). "Arene complexation of Sm, Eu, Tm and Yb atoms: a variable temperature spectroscopic investigation". Journal of Organometallic Chemistry. 688 (1–2): 49–55. doi:10.1016/j.jorganchem.2003.08.028.
- ^ La(I), Pr(I), Tb(I), Tm(I), and Yb(I) have been observed in MB8− clusters; see Li, Wan-Lu; Chen, Teng-Teng; Chen, Wei-Jia; Li, Jun; Wang, Lai-Sheng (2021). "Monovalent lanthanide(I) in borozene complexes". Nature Communications. 12 (1): 6467. doi:10.1038/s41467-021-26785-9. PMC 8578558. PMID 34753931.
- ^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 28. ISBN 978-0-08-037941-8.
- ^ Weast, Robert (1984). CRC, Handbook of Chemistry and Physics. Boca Raton, Florida: Chemical Rubber Company Publishing. pp. E110. ISBN 0-8493-0464-4.
- ^ Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.