024Transition metal · Group 6 · Period 4
Chromium
Chromium (Cr) is element 24, a transition metal in the d-block — group 6, period 4. It is a solid at room temperature with 4 electron shells (2, 8, 13, 1) and an atomic mass of 51.99616 u.
- Atomic mass
- 52.00 u
- Phase · STP
- solid
- Melting
- 2180 K · 1907 °C
- Boiling
- 2944 K · 2671 °C
- Electronegativity
- 1.66
- Density
- 7.19 g/cm³
Photograph — Jurii, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>, via Wikimedia Commons, source: https://images-of-elements.com/chromium.php
Identity
- Atomic number
- 24
- Standard atomic weight
- 52.00 u
- Category
- Transition metal
- Group
- 6
- Period
- 4
- Block
- d-block
- Oxidation states
- +6, +3, +2
Physical properties
- Melting point
- 2180 K · 1907 °C
- Boiling point
- 2944 K · 2671 °C
- Density
- 7.19 g/cm³
- Molar heat capacity
- 23.35 J/(mol·K)
- Atomic radius
- 189 pm
- Electron affinity
- 65.21 kJ/mol
Atomic structure
24protons
28neutrons
24electrons
1valence e⁻
- Noble-gas notation
- [Ar] 3d5 4s1
- Full configuration
- 1s2 2s2 2p6 3s2 3p6 4s1 3d5
- Electrons per shell
- 2, 8, 13, 1
Periodic trends
Where Chromium ranks across all 118 elements.
Ionization energies
Energy to remove each successive electron (kJ/mol).
652.91
1.6k2
3.0k3
4.7k4
6.7k5
8.7k6
15.5k7
17.8k8
20.2k9
23.6k10
Successive ionization energies (kJ/mol, log scale).
Discovery
- Discovered
- 1797
- Discovered by
- Louis Nicolas Vauquelin
- Named by
- —
- Appearance
- silvery metallic