Terbium

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| colspan="2" align="center" | Gadolinium – Terbium – Dysprosium

Tb Bk
	Image:Tb-TableImage.png Full table

General Name, Symbol, Number Terbium, Tb, 65 Chemical series Lanthanides Period, Block 6 , f Density, Hardness 8219 kg/m³, no data Appearance silvery white
Image:Tb,65.jpg Atomic properties Atomic weight 158.92534(2) amu Atomic radius (calc.) 175 (225) pm Covalent radius no data van der Waals radius no data Electron configuration [Xe]6s²4f⁹ e^-'s per energy level 2, 8, 18, 27, 8, 2 Oxidation states (Oxide) 4 (weak base) Crystal structure Hexagonal Physical properties State of matter solid (_) Melting point 1629 K (2473 °F) Boiling point 3503 K (5846 °F) Molar volume 19.3 ×10^-6 m³/mol Heat of vaporization 330.9 kJ/mol Heat of fusion 10.8 kJ/mol Vapor pressure no data Velocity of sound 2620 m/s at 293.15 K Miscellaneous Electronegativity 1.2 (Pauling scale) Specific heat capacity 180 J/(kg

Electrical conductivity 0.889 10⁶/m ohm Thermal conductivity 11.1 W/(m

1^st ionization potential 565.8 kJ/mol 2^nd ionization potential 1110 kJ/mol 3^rd ionization potential 2114 kJ/mol 4^th ionization potential 3839 kJ/mol Most stable isotopes >¹⁵⁷Tb >{syn.} >71 y >ε >0.060

iso	NA	half-life	DM	DE MeV	DP >-	¹⁵⁷Gd
¹⁵⁸Tb	{syn.}	180 y	ε	1.220	¹⁵⁸Gd
¹⁵⁸Tb	{syn.}	180 y	β^-	0.937	¹⁵⁸Dy
¹⁵⁹Tb	100%	¹⁵⁹Tb is stable with 94 neutrons

! colspan="2" align="center" bgcolor="#ffbfff" | SI units & STP are used except where noted. Terbium is a chemical element in the periodic table that has the symbol Tb and atomic number 65.

Notable characteristics

Terbium is a silvery-gray rare earth metal that is malleable, ductile and soft enough to be cut with a knife. It is reasonably stable in air, and two crystal modifications exist, with a transformation temperature of 1289°C.

Applications

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, together with ZrO₂. Terbium is also used in alloys and in the production of electronic devices, its oxide is used in green phosphors in fluorescent lamps and color TV tubes. Sodium terbium borate is used as a laser material that emits coherent light at 5460 Å.

History

Terbium was discovered by Swedish chemist Carl Gustaf Mosander in 1843 and named after the village Ytterby in Sweden, who detected it as an impurity in Yttrium-oxide, Y₂O₃. It was not isolated in pure form until the recent advent of ion-exchange techniques.

Occurrence

Terbium is never found in nature as the free element, but it is contained in many minerals, including cerite, gadolinite, monazite ((Ce,LaTh,Nd,Y)PO₄, which contains up to 0.03% of Terbium), xenotime (YPO₄) and euxenite ((Y,Ca,Er,La,Ce,U,Th)(Nb,Ta,Ti)₂O₆, which contains 1% or more of Terbium).

Compounds

Terbium compounds include:

Isotopes

Naturally occurring Terbium is composed of 1 stable isotope, 159-Tb. 33 radioisotopes have been characterized, with the most stable being 158-Tb with a half-life of 180 years, 157-Tb with a half-life of 71 years, and 160-Tb with a half-life of 72.3 days. All of the remaining radioactive isotopes have half-lifes that are less than 6.907 days, and the majority of these have half lifes that are less than 24 seconds. This element also has 18 meta states, with the most stable being 156m1-Tb (t_½ 24.4 hours), 154m2-Tb (t_½ 22.7 hours) and 154m1-Tb (t_½ 9.4 hours). The primary decay mode before the most abundant stable isotope, 159-Tb, is electron capture, and the primary mode after is beta minus decay. The primary decay products before 159-Tb are element Gd (Gadolinium) isotopes, and the primary products after are element Dy (Dysprosium) isotopes.

Precautions

As with the other lanthanides, terbium compounds are of low to moderate toxicity, although their toxicity has not been investigated in detail. Terbium has no known biological role.

References

Los Alamos National Laboratory – Terbium

External links

ca:Terbi de:Terbium eo:Terbio et:Terbium es:Terbio fr:Terbium it:Terbio nl:Terbium ja:テルビウム pl:Terb pt:Térbio ru:Тербий sl:terbij sv:Terbium Category:Chemical elements Category:Lanthanides

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