Chromium (Cr)

From Wikipedia, the free encyclopediaChromium is a chemical element with symbol Cr and atomic number 24. It is the first element in Group 6. It is a steely-gray, lustrous, hard and brittle metal which takes a high polish, resists tarnishing, and has a high melting point.

Chromium in the periodic table

SymbolCr
Atomic number24
Group6
Period4
Blockd
Element categoryTransition Metal

Physical properties

Phase at STPSolid
Density7.19 g/cm3
Atomic weight51.9962 u
Melting point2180 K
1906.85 °C
3464.33 °F
Boiling point2944 K
2670.85 °C
4839.53 °F

Atomära egenskaper

Electronegativity (Pauling Scale)1.66
Electron affinity65.21 kJ/mol
Ionization energies
1652.9 kJ/mol
2 1590.6 kJ/mol
3 2987 kJ/mol
4 4743 kJ/mol
5 6702 kJ/mol
6 8744.9 kJ/mol
7 15455 kJ/mol
8 17820 kJ/mol
9 20190 kJ/mol
10 23580 kJ/mol
11 26130 kJ/mol
12 28750 kJ/mol
13 34230 kJ/mol
14 37066 kJ/mol
15 97510 kJ/mol
16 105800 kJ/mol
17 114300 kJ/mol
18 125300 kJ/mol
19 134700 kJ/mol
20 144300 kJ/mol
21 157700 kJ/mol
22 166090 kJ/mol
23 721870 kJ/mol
24 761733 kJ/mol

Electron configuration

Electron configuration1s2 2s2 2p6 3s2 3p6 3d5 4s1
Electrons per shell2, 8, 13, 1

History

Discovered1794
Discovered byLouis Nicolas Vauquelin