Krom

24
Cr
Gruppe
6
Periode
4
Blokk
d
Protoner
Elektroner
Nøytroner
24
24
28
Generelle egenskaper
Atomnummer
24
Atomvekt
51,9961
Massetall
52
Kategori
Transisjonsmetaller
Farge
Sølv
Radioaktiv
Nei
From the Greek word chroma, color
Krystallstruktur
Body Centered Cubic
Historie
In 1797, Louis Nicolas Vauquelin received samples of crocoite ore.

In 1798, Vauquelin discovered that he could isolate metallic chromium by heating the oxide in a charcoal oven, making him the discoverer of the element.

Vauquelin was also able to detect traces of chromium in precious gemstones, such as ruby or emerald.
Elektroner per energinivå
2, 8, 13, 1
Elektronkonfigurasjon
[Ar] 3d5 4s1
Cr
Chromium oxide was used by the Chinese in the Qin dynasty over 2,000 years ago
Fysikalske egenskaper
Fase
Fast stoff
Tetthet
7,15 g/cm3
Smeltepunkt
2180,15 K | 1907 °C | 3464,6 °F
Kokepunkt
2944,15 K | 2671 °C | 4839,8 °F
Smeltevarme
20,5 kJ/mol
Fordampningsvarme
339 kJ/mol
Spesifikk varmekapasitet
0,449 J/g·K
Forekomst i jordskorpa
0,014%
Forekomst i universet
0,0015%
High
Bildekreditter: Wikimedia Commons (Alchemist-hp)
High purity chromium crystals, produced by chemical transport reaction through decomposition of chromium iodides, as well as a high purity chromium cube for comparison
CAS Number
7440-47-3
PubChem CID Number
23976
Atomegenskaper
Atomradius
128 pm
Kovalent radius
139 pm
Elektronegativitet
1,66 (Pauling-skalaen)
Ioniseringsenergi
6,7665 eV
Molart volum
7,23 cm3/mol
Termisk ledningsevne
0,937 W/cm·K
Oksidasjonstilstander
-2, -1, 1, 2, 3, 4, 5, 6
Bruksområder
Chromium is used to harden steel, manufacture stainless steel, and form many useful alloys.

It is mostly used in plating to produce a hard, beautiful surface and to prevent corrosion.

The metal is also widely used as a catalyst.

Chromium compounds are valued as pigments for their vivid green, yellow, red and orange colors.
In larger amounts, chromium can be toxic and carcinogenic
Isotoper
Stabile isotoper
50Cr, 52Cr, 53Cr, 54Cr
Ustabile isotoper
42Cr, 43Cr, 44Cr, 45Cr, 46Cr, 47Cr, 48Cr, 49Cr, 51Cr, 55Cr, 56Cr, 57Cr, 58Cr, 59Cr, 60Cr, 61Cr, 62Cr, 63Cr, 64Cr, 65Cr, 66Cr, 67Cr