Ordnungszahl: |
58 |
Name: |
Cerium |
Namensursprung: |
Named after the asteroid, Ceres, discovered two years before the element. |
Entdeckung: |
1803 by W. von Hisinger, J. Berzelius, M. Klaproth in Sweden/Germany |
Beschreibung: |
Malleable, ductile, iron-gray metal. |
Vorkommen: |
Most abundant rare earth metal. Found in many minerals like monazite sand [Ce(PO4)]. |
Verwendung: |
Its oxides are used in the optics and glass-making
industries. Its salts are used in the photography and textile industry.
Used in high-intensity carbon lamps and as alloying agents in special
metals. |
Gruppe: |
Actinide Metal |
Atomgewicht: |
140.115 |
Schmelzpunkt: |
798°C +/-3°C |
Siedepunkt: |
3433°C |
Dichte bei 293 K: |
6.78 g/cm³ |
Aggregatszustand bei Raumtemperatur: |
Solid |
Schalen: |
2,8,18,20,8,2 |
Orbitale: |
[Xe] 4f1 5d1 6s2 |
Valenzen: |
3,4 |
1. Ionisierungs- potential: |
5.5387 V |
2. Ionisierungs- potential: |
10.851 V |
3. Ionisierungs- potential: |
20.20 V |
Atomradius: |
2.70 Å |
Spezifische Wärme: |
0.19 J/gK |
Verdampfungswärme: |
414.0 kJ/mol |
Schmelzwärme: |
5.460 kJ/mol |
Thermischer Ausdehnungskoeffizient: |
5.2 10-6 K-1 |
Röntgenemission Energie / Wellenlänge: |
|
KA |
KB |
LA |
LB |
MA |
MB |
|
|
|
eV |
0 |
0 |
4840.34 |
5262.31 |
883.087 |
901.712 |
|
|
|
Å |
0 |
0 |
2.5615 |
2.3561 |
14.04 |
13.75 |
|
|
|
|
Röntgenabsorption Energie / Wellenlänge: |
|
K |
L-I |
L-II |
L-III |
M-I |
M-II |
M-III |
M-IV |
M-V |
eV |
40441 |
6549 |
6164 |
5724 |
1453 |
1273 |
1186 |
0 |
883 |
Å |
0.30658 |
1.8932 |
2.01144 |
2.16606 |
8.53306 |
9.73962 |
10.4541 |
0 |
14.0414 |
|
Röntgen Fluoreszenz Ausbeute: |
|
KA |
KB |
LA |
LB |
MA |
MB |
|
|
|
|
91.1% |
0% |
14.4% |
0% |
0% |
0% |
|
|
|
|
Nuklide: |
|
Anteil |
Gewicht |
Spin |
Halbwertszeit |
Zerfallsmodus |
Ce134 |
0% |
134 |
0 |
3016d |
EC |
Ce136 |
0.193% |
135.907 |
1/2 |
|
Stable |
Ce138 |
0.25% |
137.906 |
0 |
|
Stable |
Ce139 |
0% |
139 |
3/2 |
137.6d |
EC |
Ce140 |
88.48% |
139.905 |
0 |
|
Stable |
Ce141 |
0% |
141 |
7/2 |
32.50d |
β- |
Ce142 |
11.07% |
141.909 |
0 |
|
Stable |
Ce143 |
0% |
143 |
3/2 |
1.38d |
β- |
Ce144 |
0% |
144 |
0 |
284.6d |
β-,β- | |