Terbium, 65Tb
Terbium
Pronunciation/ˈtɜːrbiəm/ (TUR-bee-əm)
Appearancesilvery white
Standard atomic weight Ar°(Tb)
Terbium in the periodic table
Hydrogen Helium
Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon
Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon
Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton
Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon
Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon
Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson


Tb

Bk
gadoliniumterbiumdysprosium
Atomic number (Z)65
Groupf-block groups (no number)
Periodperiod 6
Block  f-block
Electron configuration[Xe] 4f9 6s2
Electrons per shell2, 8, 18, 27, 8, 2
Physical properties
Phase at STPsolid
Melting point1629 K ​(1356 °C, ​2473 °F)
Boiling point3396 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 fusion10.15 kJ/mol
Heat of vaporization391 kJ/mol
Molar heat capacity28.91 J/(mol·K)
Vapor pressure
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 1789 1979 (2201) (2505) (2913) (3491)
Atomic properties
Oxidation statescommon: +3
0,[4] +1,[5] +2,? +4[6]
ElectronegativityPauling scale: 1.2 (?)
Ionization energies
  • 1st: 565.8 kJ/mol
  • 2nd: 1110 kJ/mol
  • 3rd: 2114 kJ/mol
Atomic radiusempirical: 177 pm
Covalent radius194±5 pm
Color lines in a spectral range
Spectral lines of terbium
Other properties
Natural occurrenceprimordial
Crystal structurehexagonal close-packed (hcp) (hP2)
Lattice constants
Hexagonal close packed crystal structure for terbium
a = 360.56 pm
c = 569.66 pm (at 20 °C)[3]
Thermal expansionat r.t. poly: 10.3 µm/(m⋅K)
Thermal conductivity11.1 W/(m⋅K)
Electrical resistivityα, poly: 1.150 µΩ⋅m (at r.t.)
Magnetic orderingparamagnetic at 300 K
Molar magnetic susceptibility+146000×10−6 cm3/mol (273 K)[7]
Young's modulus55.7 GPa
Shear modulus22.1 GPa
Bulk modulus38.7 GPa
Speed of sound thin rod2620 m/s (at 20 °C)
Poisson ratio0.261
Vickers hardness450–865 MPa
Brinell hardness675–1200 MPa
CAS Number7440-27-9
History
Namingafter Ytterby (Sweden), where it was mined
Discovery and first isolationCarl Gustaf Mosander (1843)
Isotopes of terbium
Main isotopes[8] Decay
abun­dance half-life (t1/2) mode pro­duct
157Tb synth 71 y ε 157Gd
158Tb synth 180 y ε 158Gd
β 158Dy
159Tb 100% stable
 Category: Terbium
| references

Terbium is a soft, ductile, malleable silvery-white metallic chemical element with symbol Tb and atomic number 65. It is the ninth member of the lanthanide series and is traditionally counted among the rare earths. Terbium is too reactive to be found in nature as a free element, but it is contained in many minerals, including cerite, gadolinite, monazite, xenotime, and euxenite.

Terbium always occurs naturally together with the other rare earth metals. It is one of the less common rare earth elements, making up 1.2 parts per million of the Earth's crust, though this abundance is still comparable to those of molybdenum and tungsten and is about six times that of indium, antimony, and cadmium. It was discovered by Carl Gustaf Mosander: after his successful 1841 splitting of cerium into new elements, including lanthanum and "didymium" (later found to be a mixture of praseodymium and neodymium), he turned his attention to yttrium in 1843 and likewise split out two new metals. Yttrium had been named for the Ytterby quarry in Sweden where it was originally discovered in gadolinite; since it had now been split into three parts, Mosander likewise split the name of Ytterby into three parts to name his new elements terbium and erbium. Due to later confusion, the names of terbium and erbium were later switched from Mosander's original. Even Mosander's terbium was impure; in 1878 Jean Charles Galissard de Marignac seperated out the new element gadolinium from Mosander's terbium. Highly pure terbium was not obtained until the advent of ion exchange techniques, due to the extreme similarity of the lanthanides hindering attempts at their separation.

Like most rare earth elements, terbium most readily forms the +3 oxidation state, which is the only stable state in aqueous solution, although the +4 oxidation state is known in some solid compounds. Aqueous Tb3+ ions are very pale pink and almost colourless; the reddish-brown Tb4+ ions are quickly reduced by water to Tb3+.

Terbium is used to dope calcium fluoride, calcium tungstate and strontium molybdate, materials that are used in solid-state devices, and as a crystal stabilizer of fuel cells which 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. Most of the world's terbium supply is used in green phosphors. Terbium oxide is in fluorescent lamps and TV tubes. 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 for standard illumination in indoor lighting.

Characteristics

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Physical

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Terbium is the ninth member of the lanthanide series. In the periodic table, it appears between the lanthanides gadolinium to its left and dysprosium to its right, and above the actinide berkelium. It is malleable, ductile and soft enough to be cut with a knife.[9] It is relatively stable in air compared to the earlier, more reactive lanthanides in the first half of the lanthanide series.[10] The 65 electrons of a terbium atom are arranged in the electron configuration [Xe]4f96s2; normally, only three electrons can be removed before the nuclear charge becomes too great to allow further ionization, but in the case of terbium, the stability of the half-filled [Xe]4f7 configuration allows further ionization of a fourth electron in the presence of very strong oxidizing agents such as fluorine gas.[9]

Terbium exists in two crystal allotropes with a transformation temperature of 1289 °C between them.[9]

Isotopes

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Chemistry

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History

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Occurrence and production

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Applications

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Biological role and precautions

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References

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Bibliography

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  • Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
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  1. ^ "Standard Atomic Weights: Terbium". CIAAW. 2021.
  2. ^ 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.
  3. ^ 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.
  4. ^ 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.
  5. ^ 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.
  6. ^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 28. ISBN 978-0-08-037941-8.
  7. ^ Weast, Robert (1984). CRC, Handbook of Chemistry and Physics. Boca Raton, Florida: Chemical Rubber Company Publishing. pp. E110. ISBN 0-8493-0464-4.
  8. ^ 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.
  9. ^ a b c Cite error: The named reference CRC was invoked but never defined (see the help page).
  10. ^ "Rare-Earth Metal Long Term Air Exposure Test". Retrieved 2009-05-05.