Krom

24
Cr
Gruppe
6
Periode
4
Blokk
d
Protons
Electrons
Neutrons
24
24
28
Generelle eigenskapar
Atomnummer
24
Atommasse
51,9961
Mass Number
52
Kategori
Transisjonsmetall
Farge
Silver
Radioactive
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.
Elektron 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
Fysiske eigenskapar
Tilstandsform
Fast stoff
Tettleik
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
Fordampingsvarme
339 kJ/mol
Spesifikk varmekapasitet
0,449 J/g·K
Abundance in Earth's crust
0,014%
Abundance in Universe
0,0015%
High
Image Credits: 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
Atom eigenskapar
Atomradius
128 pm
Kovalent radius
139 pm
Elektronegativitet
1,66 (Paulings skala)
Ioniseringspotensial
6,7665 eV
Molart volum
7,23 cm3/mol
Termisk konduktivitet
0,937 W/cm·K
Oksidasjonstrinn
-2, -1, 1, 2, 3, 4, 5, 6
Applications
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
Isotopes
Stable Isotopes
50Cr, 52Cr, 53Cr, 54Cr
Unstable Isotopes
42Cr, 43Cr, 44Cr, 45Cr, 46Cr, 47Cr, 48Cr, 49Cr, 51Cr, 55Cr, 56Cr, 57Cr, 58Cr, 59Cr, 60Cr, 61Cr, 62Cr, 63Cr, 64Cr, 65Cr, 66Cr, 67Cr