Revision as of 20:56, 20 December 2011 by imported>Deflective
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Chromium, 24Cr| File:Chromium crystals and 1cm3 cube.jpg |
| Chromium |
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| Appearance | silvery metallic |
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| Standard atomic weight Ar, std(Cr) | Template:Val[1] |
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| Chromium in the periodic table |
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|
|
| Atomic number (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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| Electron configuration | [Ar] 3d5 4s1 |
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| Electrons per shell | 2, 8, 13, 1 |
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| Physical properties |
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| Phase at STP | solid |
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| Melting point | 2180 K (1907 °C, 3465 °F) |
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| Boiling point | 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 of fusion | 21.0 kJ/mol |
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| Heat of vaporization | 339.5 kJ/mol |
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| Molar heat capacity | 23.35 J/(mol·K) |
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Vapor pressure
| P (Pa)
|
1
|
10
|
100
|
1 k
|
10 k
|
100 k
|
| at T (K)
|
1656
|
1807
|
1991
|
2223
|
2530
|
2942
|
|
| Atomic properties |
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| Oxidation states | −4, −2, −1, 0, +1, +2, +3, +4, +5, +6 (depending on the oxidation state, an acidic, basic, or amphoteric oxide) |
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| Electronegativity | Pauling scale: 1.66 |
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| Ionization 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 of chromium |
| Other properties |
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| Natural occurrence | primordial |
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| Crystal structure | body-centered cubic (bcc) |
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| Speed of sound 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 ordering | 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 hardness | 8.5 |
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| Vickers hardness | 1060 MPa |
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| Brinell hardness | 1120 MPa |
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| CAS Number | 7440-47-3 |
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| Main isotopes of chromium |
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|
|
Category: Chromium | references |
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References
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