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- | |