| Ordnungszahl: |
55 |
| Name: |
Cesium |
| Namensursprung: |
Latin: coesius (sky blue); for the blue lines of its spectrum. |
| Entdeckung: |
1860 by Gustov Kirchoff, Robert Bunsen in Germany |
| Beschreibung: |
Very soft, light gray, ductile metal. |
| Vorkommen: |
Found in pollucite [(Cs4Al4Si9O26)·H2O] and as trace in lepidolite. |
| Verwendung: |
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 ionizes readily, it is used as an ion rocket motor propellant. |
| Gruppe: |
Alkali Metal |
| Atomgewicht: |
132.90543 |
| Schmelzpunkt: |
28.4°C |
| Siedepunkt: |
669.3°C |
| Dichte bei 293 K: |
1.873 g/cm³ |
| Aggregatszustand bei Raumtemperatur: |
Solid |
| Schalen: |
2,8,18,18,8,1 |
| Orbitale: |
[Xe] 6s1 |
| Valenzen: |
1 |
| 1. Ionisierungs- potential: |
3.8939 V |
| 2. Ionisierungs- potential: |
25.10 V |
| 3. Ionisierungs- potential: |
-- |
| Atomradius: |
3.34 Å |
| Spezifische Wärme: |
0.24 J/gK |
| Verdampfungswärme: |
67.740 kJ/mol |
| Schmelzwärme: |
2.092 kJ/mol |
| Thermischer Ausdehnungskoeffizient: |
100 10-6 K-1 |
| Röntgenemission Energie / Wellenlänge: |
| |
KA |
KB |
LA |
LB |
MA |
MB |
|
|
|
| eV |
30857.5 |
0 |
4286.59 |
4619.94 |
0 |
0 |
|
|
|
| Å |
0.4018 |
0 |
2.8924 |
2.6837 |
0 |
0 |
|
|
|
|
| Röntgenabsorption Energie / Wellenlänge: |
| |
K |
L-I |
L-II |
L-III |
M-I |
M-II |
M-III |
M-IV |
M-V |
| eV |
35982 |
5714 |
5360 |
5012 |
1217 |
1065 |
0 |
0 |
726 |
| Å |
0.34457 |
2.16985 |
2.31316 |
2.47377 |
10.1878 |
11.6418 |
0 |
0 |
17.0779 |
|
| Röntgen Fluoreszenz Ausbeute: |
| |
KA |
KB |
LA |
LB |
MA |
MB |
|
|
|
| |
89.5% |
0% |
11.8% |
0% |
0% |
0% |
|
|
|
|
| Nuklide: |
| |
Anteil |
Gewicht |
Spin |
Halbwertszeit |
Zerfallsmodus |
| Cs126 |
0% |
126 |
1 |
1.64m |
β+,EC |
| Cs129 |
0% |
129 |
1/2 |
1.336d |
EC,β+ |
| Cs131 |
0% |
131 |
5/2 |
9.69d |
EC |
| Cs132 |
0% |
132 |
2 |
6.48d |
EC,β+,β- |
| Cs133 |
100% |
133.905 |
7/2 |
|
Stable |
| Cs134 |
0% |
134 |
4 |
2.065y |
β-,EC |
| Cs134m |
0% |
134 |
8 |
2.91h |
IT |
| Cs135 |
0% |
135 |
7/2 |
2.3E06y |
β- |
| Cs136 |
0% |
136 |
5 |
13.16d |
β- |
| Cs137 |
0% |
137 |
7/2 |
30.17y |
β-,β- |
| Cs138 |
0% |
138 |
3 |
32.2m |
β- |
| Cs139 |
0% |
139 |
7/2 |
9.3m |
β- |
|
