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Pronunciation | (LAN-thə-nəm) |
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Appearance | silvery white |
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| 138.90547(7)[1] |
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Atomic number (Z) | 57 |
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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] 5d1 6s2 |
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Electrons per shell | 2, 8, 18, 18, 9, 2 |
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Phase at STP | solid |
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Melting point | 1193 K (920 °C, 1688 °F) |
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Boiling point | 3737 K (3464 °C, 6267 °F) |
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Density (near r.t.) | 6.162 g/cm3 |
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when liquid (at m.p.) | 5.94 g/cm3 |
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Heat of fusion | 6.20 kJ/mol |
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Heat of vaporization | 400 kJ/mol |
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Molar heat capacity | 27.11 J/(mol·K) |
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Vapor pressure (extrapolated)
P (Pa) |
1 |
10 |
100 |
1 k |
10 k |
100 k |
at T (K) |
2005 |
2208 |
2458 |
2772 |
3178 |
3726 |
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Oxidation states | 0,[2] +1,[3] +2, +3 (a strongly basic oxide) |
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Electronegativity | Pauling scale: 1.10 |
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Ionization energies | - 1st: 538.1 kJ/mol
- 2nd: 1067 kJ/mol
- 3rd: 1850.3 kJ/mol
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Atomic radius | empirical: 187 pm |
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Covalent radius | 207±8 pm |
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Spectral lines of lanthanum |
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Natural occurrence | primordial |
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Crystal structure | double hexagonal close-packed (dhcp) |
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Speed of sound thin rod | 2475 m/s (at 20 °C) |
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Thermal expansion | α, poly: 12.1 µm/(m⋅K) (at r.t.) |
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Thermal conductivity | 13.4 W/(m⋅K) |
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Electrical resistivity | α, poly: 615 nΩ⋅m (at r.t.) |
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Magnetic ordering | paramagnetic[4] |
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Molar magnetic susceptibility | +118.0×10−6 cm3/mol (298 K)[5] |
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Young's modulus | α form: 36.6 GPa |
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Shear modulus | α form: 14.3 GPa |
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Bulk modulus | α form: 27.9 GPa |
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Poisson ratio | α form: 0.280 |
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Mohs hardness | 2.5 |
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Vickers hardness | 360–1750 MPa |
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Brinell hardness | 350–400 MPa |
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CAS Number | 7439-91-0 |
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Discovery | Carl Gustaf Mosander (1838) |
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Category: Lanthanum | references |