Thulium

Thulium, ₆₉Tm

Thulium
Pronunciation	/ˈθjuːliəm/ ​(THEW-lee-əm)
Appearance	silvery gray
Standard atomic weight Ar°(Tm)
	168.934219±0.000005[1] 168.93±0.01 (abridged)[2]
Thulium 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 – ↑ Tm ↓ Md erbium ← thulium → ytterbium
Atomic number (Z)	69
Group	f-block groups (no number)
Period	period 6
Block	f-block
Electron configuration	[Xe] 4f13 6s2
Electrons per shell	2, 8, 18, 31, 8, 2
Physical properties
Phase at STP	solid
Melting point	1818 K ​(1545 °C, ​2813 °F)
Boiling point	2223 K ​(1950 °C, ​3542 °F)
Density (at 20° C)	9.320 g/cm3 [3]
when liquid (at m.p.)	8.56 g/cm3
Heat of fusion	16.84 kJ/mol
Heat of vaporization	191 kJ/mol
Molar heat capacity	27.03 J/(mol·K)
Vapor pressure P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 1117 1235 1381 1570 (1821) (2217)
Atomic properties
Oxidation states	common: +3 0,[4] +1,[5] +2[6]
Electronegativity	Pauling scale: 1.25
Ionization energies	1st: 596.7 kJ/mol 2nd: 1160 kJ/mol 3rd: 2285 kJ/mol
Atomic radius	empirical: 176 pm
Covalent radius	190±10 pm
Spectral lines of thulium
Other properties
Natural occurrence	primordial
Crystal structure	​hexagonal close-packed (hcp) (hP2)
Lattice constants	a = 353.77 pm c = 555.39 pm (at 20 °C)[3]
Thermal expansion	poly: 13.3 µm/(m⋅K) (at r.t.)
Thermal conductivity	16.9 W/(m⋅K)
Electrical resistivity	poly: 676 nΩ⋅m (at r.t.)
Magnetic ordering	paramagnetic (at 300 K)
Molar magnetic susceptibility	+25500×10−6 cm3/mol (291 K)[7]
Young's modulus	74.0 GPa
Shear modulus	30.5 GPa
Bulk modulus	44.5 GPa
Poisson ratio	0.213
Vickers hardness	470–650 MPa
Brinell hardness	470–900 MPa
CAS Number	7440-30-4
History
Naming	after Thule, a mythical region in Scandinavia
Discovery and first isolation	Per Teodor Cleve (1879)
Isotopes of thulium v e
Main isotopes[8] Decay abun­dance half-life (t1/2) mode pro­duct 167Tm synth 9.25 d ε 167Er 168Tm synth 93.1 d β+ 168Er 169Tm 100% stable 170Tm synth 128.6 d β− 170Yb 171Tm synth 1.92 y β− 171Yb
Category: Thulium view talk edit | references

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.

In 1879, the Swedish chemist Per Teodor Cleve separated two previously unknown components, which he called holmia and thulia, from the rare-earth mineral erbia; these were the oxides of holmium and thulium, respectively. A relatively pure sample of thulium metal was first obtained in 1911.

Like the other lanthanides, its most common oxidation state is +3, seen in its oxide, halides and other compounds. In aqueous solution, like compounds of other late lanthanides, soluble thulium compounds form coordination complexes with nine water molecules.