| Ordnungszahl: |
24 |
| Name: |
Chromium |
| Namensursprung: |
Greek: chrôma (color). |
| Entdeckung: |
1797 by Louis Vauquelin in France |
| Beschreibung: |
Very hard, crystalline, steel-gray metal. The pure metal has a blue-white color. It is hard, brittle and corrsion-resistant at normal temperatures. |
| Vorkommen: |
Chromite [Fe,Mg(CrO4)] is its most important mineral. Produced commercially by heating its ore in the presence of silicon or aluminium. |
| Verwendung: |
Used to make stainless steel. It gives the color to rubies and emeralds. Iron-nickel-chromium alloys in various percentages yield an incredible variety of the most important metals in modern technology. |
| Gruppe: |
Transition Metal |
| Atomgewicht: |
51.9961 |
| Schmelzpunkt: |
1857°C |
| Siedepunkt: |
2672°C |
| Dichte bei 293 K: |
7.19 g/cm³ |
| Aggregatszustand bei Raumtemperatur: |
Solid |
| Schalen: |
2,8,13,1 |
| Orbitale: |
[Ar] 3d5 4s1 |
| Valenzen: |
2,3,6 |
| 1. Ionisierungs- potential: |
6.7666 V |
| 2. Ionisierungs- potential: |
16.50 V |
| 3. Ionisierungs- potential: |
30.96 V |
| Atomradius: |
1.85 Å |
| Spezifische Wärme: |
0.45 J/gK |
| Verdampfungswärme: |
344.30 kJ/mol |
| Schmelzwärme: |
16.90 kJ/mol |
| Thermischer Ausdehnungskoeffizient: |
4.9 10-6 K-1 |
| Röntgenemission Energie / Wellenlänge: |
| |
KA |
KB |
LA |
LB |
MA |
MB |
|
|
|
| eV |
5411.85 |
5946.91 |
572.945 |
582.912 |
0 |
0 |
|
|
|
| Å |
2.291 |
2.08487 |
21.64 |
21.27 |
0 |
0 |
|
|
|
|
| Röntgenabsorption Energie / Wellenlänge: |
| |
K |
L-I |
L-II |
L-III |
M-I |
M-II |
M-III |
M-IV |
M-V |
| eV |
5990 |
741 |
691 |
598 |
0 |
0 |
0 |
0 |
0 |
| Å |
2.06987 |
16.7322 |
17.9429 |
20.7333 |
0 |
0 |
0 |
0 |
0 |
|
| Röntgen Fluoreszenz Ausbeute: |
| |
KA |
KB |
LA |
LB |
MA |
MB |
|
|
|
| |
28.1% |
0% |
0.2% |
0% |
0% |
0% |
|
|
|
|
| Nuklide: |
| |
Anteil |
Gewicht |
Spin |
Halbwertszeit |
Zerfallsmodus |
| Cr49 |
0% |
49 |
5/2 |
42.3m |
β+ |
| Cr50 |
4.31% |
49.946 |
0 |
|
Stable |
| Cr51 |
0% |
50.945 |
7/2 |
27.70d |
EC |
| Cr52 |
83.76% |
51.9405 |
0 |
|
Stable |
| Cr53 |
9.55% |
52.9407 |
3/2 |
|
Stable |
| Cr54 |
2.38% |
53.9389 |
0 |
|
Stable |
|
