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Cerium |
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Pronunciation | (SEER-ee-əm) |
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Appearance | sillery white |
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Standard atomic weight Ar, std(Ce) | 7002140116000000000♠140.116(1)[1] |
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Cerium in the periodic cairt |
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Atomic nummer (Z) | 58 |
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Group | group n/a |
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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] 4f1 5d1 6s2[2] |
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Electrons per shell | 2, 8, 18, 19, 9, 2 |
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Pheesical properties |
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Phase at STP | solit |
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Meltin pynt | 1068 K (795 °C, 1463 °F) |
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Bylin pynt | 3716 K (3443 °C, 6229 °F) |
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Density (near r.t.) | 6.770 g/cm3 |
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when liquid (at m.p.) | 6.55 g/cm3 |
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Heat o fusion | 5.46 kJ/mol |
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Heat o vapourisation | 398 kJ/mol |
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Molar heat capacity | 26.94 J/(mol·K) |
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Vapour pressur
P (Pa) |
1 |
10 |
100 |
1 k |
10 k |
100 k |
at T (K) |
1992 |
2194 |
2442 |
2754 |
3159 |
3705 |
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Atomic properties |
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Oxidation states | +1, +2, +3, +4 (a mildly basic oxide) |
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Electronegativity | Pauling scale: 1.12 |
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Atomic radius | empirical: 181.8 pm |
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Covalent radius | 204±9 pm |
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Spectral lines o cerium |
Ither properties |
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Naitural occurrence | primordial |
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Creestal structur | face-centred cubic (fcc) |
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Speed o soond thin rod | 2100 m/s (at 20 °C) |
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Thermal expansion | (r.t.) (γ, poly) 6.3 µm/(m·K) |
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Thermal conductivity | 11.3 W/(m·K) |
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Electrical resistivity | (r.t.) (β, poly) 828 n Ω·m |
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Magnetic orderin | paramagnetic[3] |
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Young's modulus | (γ form) 33.6 GPa |
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Shear modulus | (γ form) 13.5 GPa |
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Bulk modulus | (γ form) 21.5 GPa |
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Poisson ratio | (γ form) 0.24 |
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Mohs haurdness | 2.5 |
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Vickers haurdness | 270 MPa |
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Brinell haurdness | 412 MPa |
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CAS Nummer | 7440-45-1 |
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History |
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Namin | efter dwarf planet Ceres, itsel named efter Roman deity o agricultur Ceres |
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Diskivery | Martin Heinrich Klaproth, Jöns Jakob Berzelius, Wilhelm Hisinger (1803) |
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First isolation | Carl Gustaf Mosander (1839) |
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Main isotopes o cerium |
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Isotope |
Abundance |
Hauf-life (t1/2) |
Decay mode |
Product |
134Ce |
syn |
3.16 d |
ε |
134La |
136Ce |
0.185% |
>3.8×1016 y |
(β+β+) |
136Ba |
138Ce |
0.251% |
>1.5×1014 y |
(β+β+) |
138Ba |
139Ce |
syn |
137.640 d |
ε |
139La |
140Ce |
88.450% |
- |
(SF) |
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141Ce |
syn |
32.501 d |
β− |
141Pr |
142Ce |
11.114% |
>5×1016 y |
(β−β−) |
142Nd |
(α) |
138Ba |
144Ce |
syn |
284.893 d |
β− |
144Pr |
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Decay modes in parentheses is predict, but hisna yet been observed |
| references |