Krom

24
Cr
Skupina
6
Perioda
4
Blok
d
Protons
Electrons
Neutrons
24
24
28
General Properties
Vrstno število
24
Atomska teža
51,9961
Mass Number
52
Kategorija
Prehodne kovine
Barva
Silver
Radioactive
Ne
From the Greek word chroma, color
Kristalna struktura
Telesno centrirana kubična
Zgodovina
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.
Electrons per shell
2, 8, 13, 1
Razporeditev elektronov
[Ar] 3d5 4s1
Cr
Chromium oxide was used by the Chinese in the Qin dynasty over 2,000 years ago
Physical Properties
Faza snovi
Trdnina
Gostota
7,15 g/cm3
Tališče
2180,15 K | 1907 °C | 3464,6 °F
Vrelišče
2944,15 K | 2671 °C | 4839,8 °F
Talilna toplota
20,5 kJ/mol
Izparilna toplota
339 kJ/mol
Toplotna kapaciteta
0,449 J/g·K
Abundance in Earth's crust
0,014%
Abundance in Universe
0,0015%
High
Zasluge za slike: 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
Atomic Properties
Atomski polmer
128 pm
Kovalentni polmer
139 pm
Elektronegativnost
1,66 (Paulingova lestvica)
Ionization Potential
6,7665 eV
Atomic Volume
7,23 cm3/mol
Toplotna prevodnost
0,937 W/cm·K
Oksidacijska stanja
-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