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 | |