Template:Infobox thulium

Thulium,  ₆₉Tm

General properties
Name, symbol	thulium, Tm
Appearance	silvery gray
Pronunciation	/ˈθjuːliəm/ THEW-lee-əm
Thulium in the periodic table
– ↑ Tm ↓ Md erbium ← thulium → ytterbium
Atomic number (Z)	69
Group, block	group n/a, f-block
Period	period 6
Element category	lanthanide
Standard atomic weight (±) (Ar)	168.93422(2)
Electron configuration	[Xe] 4f13 6s2
per shell	2, 8, 18, 31, 8, 2
Physical properties
Phase	solid
Melting point	1818 K ​(1545 °C, ​2813 °F)
Boiling point	2223 K ​(1950 °C, ​3542 °F)
Density near r.t.	9.32 g/cm3
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	2, 3 ​(a basic oxide)
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
Miscellanea
Crystal structure	​hexagonal close-packed (hcp)
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)
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)
Most stable isotopes of thulium
iso NA half-life DM DE (MeV) DP 167Tm syn 9.25 d ε 0.748 167Er 168Tm syn 93.1 d ε 1.679 168Er 169Tm 100% – (α) 1.2004 165Ho 170Tm syn 128.6 d β− 0.968 170Yb 171Tm syn 1.92 y β− 0.096 171Yb
Decay modes in parentheses are predicted, but have not yet been observed

References

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