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| Caesium | Césium | Cezij | Cesio | Cäsium | ||||||||||||||||||||
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Cs Caesium |
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- Caesium was discovered by Robert Bunsen and Gustav Kirchhoff (Germany) in 1860. The origin of the name comes from the Latin word caesius meaning sky blue or heavenly blue. It is very soft, light grey, ductile metal. Reacts readily with oxygen. Reacts explosively with water.
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ALKALIMETALLE | |
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| Relative Atommasse: | 132.90545(2) | Elektronenkonfiguration: | [Xe] 6s1 |
| Oxidationszustände: | +1 | Elekronegativität: | 0.79 |
| Wärmeleitfähigkeit: | 35.9 W m-1 K-1 | Elektrische Widerstandskraft (20 °C): | 20 μΩcm |
| Atomradius: | 265.5 pm | Zustand (20 °C): | fest |
| Dichte (g dm-3): | 1873 (293 K) 1843 (m.p.) |
Atomvolumen (cm3 mol-1): | 70.96 (293 K) 72.11 (m.p.) |
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THERMISCHE EIGENSCHAFTEN | |
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| Schmelzpunkt: | 798 °C | Bildungsenergie: | 2.09 kJ mol-1 |
| Siedepunkt: | 3443 °C | Verdampfungsenergie: | 66.5 kJ mol-1 |
| Kritische Temperatur: | 1784 °C | Zerstäubungsenergie: | 77.58 kJ mol-1 |
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IONISIERUNGSENERGIE UND HÄUFIGKEIT | |
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| 1. Ionisierungenergie: | 375.71 kJ mol-1 | Häufigkeit des Elements (Luft): | - ppm |
| 2. Ionisierungenergie: | 2234.37 kJ mol-1 | Häufigkeit des Elements (Erdkruste): | 1 ppm |
| 3. Ionisierungenergie: | - kJ mol-1 | Häufigkeit des Elements (Ozean): | 0.0005 ppm |
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ISOTOPE | |
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Isotope | Relative Atommasse | Häufigkeit (%) |
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133Cs | 132.905447(3) | 100 |
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MINERALIEN UND GEBRAUCH | |
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- Caesium is found in pollucite [(Cs4Al4Si9O26).H2O] and as trace in lepidolite. Used as a 'getter' to remove air traces in vacuum and cathode-ray tubes. Also used in producing photoelectric devices and atomic clocks. Since it ionises readily, it is used as an ion rocket motor propellant. The price of 99.8 % pure cesium metal is 461.80 € for 50 g.
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REDUKTIONSPOTENTIALE | |
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Balanced half-reaction | Eo / V | Anmerkung |
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Cs+ + e-  Cs(s) |
- 2.91 | |
