[[Category:Template:Pagetype with short description]]
Caesium, 55Cs |
| Caesium |
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| Pronunciation | (Template:Respell) |
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| Alternative name | cesium (US, informal) |
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| Appearance | pale gold |
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| Standard atomic weight Ar, std(Cs) | Template:Val[1] |
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| Caesium in the periodic table |
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|
|
| Atomic number (Z) | 55 |
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| Group | group 1: H and alkali metals |
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| Period | period 6 |
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| Block | s-block |
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| Electron configuration | [Xe] 6s1 |
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| Electrons per shell | 2, 8, 18, 18, 8, 1 |
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| Physical properties |
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| Phase at STP | solid |
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| Melting point | 301.7 K (28.5 °C, 83.3 °F) |
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| Boiling point | 944 K (671 °C, 1240 °F) |
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| Density (near r.t.) | 1.93 g/cm3 |
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| when liquid (at m.p.) | 1.843 g/cm3 |
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| Critical point | 1938 K, 9.4 MPa[2] |
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| Heat of fusion | 2.09 kJ/mol |
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| Heat of vaporization | 63.9 kJ/mol |
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| Molar heat capacity | 32.210 J/(mol·K) |
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Vapor pressure
| P (Pa)
|
1
|
10
|
100
|
1 k
|
10 k
|
100 k
|
| at T (K)
|
418
|
469
|
534
|
623
|
750
|
940
|
|
| Atomic properties |
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| Oxidation states | −1, +1[3] (a strongly basic oxide) |
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| Electronegativity | Pauling scale: 0.79 |
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| Ionization energies | - 1st: 375.7 kJ/mol
- 2nd: 2234.3 kJ/mol
- 3rd: 3400 kJ/mol
-
|
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| Atomic radius | empirical: 265 pm |
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| Covalent radius | 244±11 pm |
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| Van der Waals radius | 343 pm |
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| Spectral lines of caesium |
| Other properties |
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| Natural occurrence | primordial |
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| Crystal structure | body-centered cubic (bcc) |
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| Thermal expansion | 97 µm/(m·K) (at 25 °C) |
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| Thermal conductivity | 35.9 W/(m·K) |
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| Electrical resistivity | 205 nΩ·m (at 20 °C) |
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| Magnetic ordering | paramagnetic[4] |
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| Young's modulus | 1.7 GPa |
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| Bulk modulus | 1.6 GPa |
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| Mohs hardness | 0.2 |
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| Brinell hardness | 0.14 MPa |
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| CAS Number | 7440-46-2 |
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| History |
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| Naming | from Latin caesius, sky blue, for its spectral colours |
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| Discovery | Robert Bunsen and Gustav Kirchhoff (1860) |
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| First isolation | Carl Setterberg (1882) |
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| Main isotopes of caesium |
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|
|
Category: Caesium | references |
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References
These references will appear in the article, but this list appears only on this page.
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