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Chromium |
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Appearance | sillery metallic |
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Standard atomic weight Ar, std(Cr) | 7001519961000000000♠51.9961(6)[1] |
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Chromium in the periodic cairt |
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Atomic nummer (Z) | 24 |
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Group | group 6 |
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Period | period 4 |
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Block | d-block |
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Element category | Transeetion metal |
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Electron confeeguration | [Ar] 3d5 4s1 |
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Electrons per shell | 2, 8, 13, 1 |
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Pheesical properties |
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Phase at STP | solit |
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Meltin pynt | 2180 K (1907 °C, 3465 °F) |
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Bylin pynt | 2944 K (2671 °C, 4840 °F) |
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Density (near r.t.) | 7.19 g/cm3 |
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when liquid (at m.p.) | 6.3 g/cm3 |
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Heat o fusion | 21.0 kJ/mol |
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Heat o vapourisation | 339.5 kJ/mol |
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Molar heat capacity | 23.35 J/(mol·K) |
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Vapour pressur
P (Pa) |
1 |
10 |
100 |
1 k |
10 k |
100 k |
at T (K) |
1656 |
1807 |
1991 |
2223 |
2530 |
2942 |
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Atomic properties |
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Oxidation states | −4, −2, −1, 0, +1, +2, +3, +4, +5, +6 (dependin on the oxidation state, an acidic, basic, or amphoteric oxide) |
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Electronegativity | Pauling scale: 1.66 |
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Ionisation energies | |
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Atomic radius | empirical: 128 pm |
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Covalent radius | 139±5 pm |
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Spectral lines o chromium |
Ither properties |
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Naitural occurrence | primordial |
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Creestal structur | body-centred cubic (bcc) |
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Speed o soond thin rod | 5940 m/s (at 20 °C) |
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Thermal expansion | 4.9 µm/(m·K) (at 25 °C) |
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Thermal conductivity | 93.9 W/(m·K) |
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Electrical resistivity | 125 n Ω·m (at 20 °C) |
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Magnetic orderin | AFM (rather: SDW[2]) |
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Young's modulus | 279 GPa |
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Shear modulus | 115 GPa |
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Bulk modulus | 160 GPa |
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Poisson ratio | 0.21 |
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Mohs haurdness | 8.5 |
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Vickers haurdness | 1060 MPa |
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Brinell haurdness | 1120 MPa |
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CAS Nummer | 7440-47-3 |
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History |
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Diskivery | Louis Nicolas Vauquelin (1797) |
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First isolation | Louis Nicolas Vauquelin (1798) |
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Main isotopes o chromium |
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Isotope |
Abundance |
Hauf-life (t1/2) |
Decay mode |
Product |
50Cr |
4.345% |
>1.3×1018 y |
(β+β+) |
50Ti |
51Cr |
syn |
27.7025 d |
ε |
51V |
γ |
- |
52Cr |
83.789% |
stable |
53Cr |
9.501% |
stable |
54Cr |
2.365% |
stable |
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Decay modes in parentheses are predictit, but hae nae yet been observed |
| references |