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Pronunciation | (THEW-lee-əm) |
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Appearance | silvery gray |
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| 168.934218(6)[1] |
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Atomic number (Z) | 69 |
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Group | f-block groups (no number) |
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Period | period 6 |
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Block | f-block |
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Electron configuration | [Xe] 4f13 6s2 |
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Electrons per shell | 2, 8, 18, 31, 8, 2 |
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Phase at STP | solid |
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Melting point | 1818 K (1545 °C, 2813 °F) |
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Boiling point | 2223 K (1950 °C, 3542 °F) |
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Density (near r.t.) | 9.32 g/cm3 |
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when liquid (at m.p.) | 8.56 g/cm3 |
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Heat of fusion | 16.84 kJ/mol |
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Heat of vaporization | 191 kJ/mol |
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Molar heat capacity | 27.03 J/(mol·K) |
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Vapor pressure
P (Pa) |
1 |
10 |
100 |
1 k |
10 k |
100 k |
at T (K) |
1117 |
1235 |
1381 |
1570 |
(1821) |
(2217) |
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Oxidation states | 0,[2] +1,[3] +2, +3 (a basic oxide) |
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Electronegativity | Pauling scale: 1.25 |
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Ionization energies | - 1st: 596.7 kJ/mol
- 2nd: 1160 kJ/mol
- 3rd: 2285 kJ/mol
-
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Atomic radius | empirical: 176 pm |
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Covalent radius | 190±10 pm |
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Spectral lines of thulium |
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Natural occurrence | primordial |
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Crystal structure | hexagonal close-packed (hcp) |
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Thermal expansion | poly: 13.3 µm/(m⋅K) (at r.t.) |
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Thermal conductivity | 16.9 W/(m⋅K) |
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Electrical resistivity | poly: 676 nΩ⋅m (at r.t.) |
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Magnetic ordering | paramagnetic (at 300 K) |
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Molar magnetic susceptibility | +25500×10−6 cm3/mol (291 K)[4] |
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Young's modulus | 74.0 GPa |
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Shear modulus | 30.5 GPa |
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Bulk modulus | 44.5 GPa |
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Poisson ratio | 0.213 |
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Vickers hardness | 470–650 MPa |
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Brinell hardness | 470–900 MPa |
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CAS Number | 7440-30-4 |
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Naming | after Thule, a mythical region in Scandinavia |
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Discovery and first isolation | Per Teodor Cleve (1879) |
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Main isotopes[5] |
Decay |
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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 |
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Category: Thulium | references |