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Lanthanum |
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Pronunciation | (LAN-thə-nəm) |
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Appearance | sillery white |
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Standard atomic weight Ar, std(La) | 7002138905470000000♠138.90547(7)[1] |
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Lanthanum in the periodic cairt |
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Atomic nummer (Z) | 57 |
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Group | group 3 |
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Period | period 6 |
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Block | f-block |
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Element category | Lanthanide |
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Electron confeeguration | [Xe] 5d1 6s2 |
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Electrons per shell | 2, 8, 18, 18, 9, 2 |
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Pheesical properties |
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Phase at STP | solit |
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Meltin pynt | 1193 K (920 °C, 1688 °F) |
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Bylin pynt | 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 o fusion | 6.20 kJ/mol |
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Heat o vapourisation | 402.1 kJ/mol |
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Molar heat capacity | 27.11 J/(mol·K) |
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Vapour pressur (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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Atomic properties |
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Oxidation states | 0,[2] +1, +2, +3 strangly basic |
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Electronegativity | Pauling scale: 1.10 |
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Atomic radius | empirical: 187 pm |
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Covalent radius | 207±8 pm |
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Spectral lines o lanthanum |
Ither properties |
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Naitural occurrence | primordial |
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Creestal structur | hexagonal |
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Speed o soond thin rod | 2475 m/s (at 20 °C) |
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Thermal expansion | (r.t.) (α, poly) 12.1 µm/(m·K) |
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Thermal conductivity | 13.4 W/(m·K) |
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Electrical resistivity | (r.t.) (α, poly) 615 n Ω·m |
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Magnetic orderin | paramagnetic[3] |
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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 haurdness | 2.5 |
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Vickers haurdness | 491 MPa |
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Brinell haurdness | 363 MPa |
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CAS Nummer | 7439-91-0 |
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History |
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Diskivery | Carl Gustaf Mosander (1838) |
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Main isotopes o lanthanum |
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Isotope |
Abundance |
Hauf-life (t1/2) |
Decay mode |
Product |
137La |
syn |
6×104 y |
ε |
137Ba |
138La |
0.090% |
1.05×1011 y |
ε |
138Ba |
β− |
138Ce |
139La |
99.910% |
- |
(SF) |
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Decay modes in parentheses are predicted, but hisna yet been observed |
| references |