Chromium (Cr) – element 24
Chromium is a chemical element with the symbol Cr and atomic number 24. It is a transition metal in group 6, period 4 of the periodic table (d-block), and is a solid at room temperature.
Chromium (Cr) has atomic number 24, atomic mass 51.996 u and electron configuration [Ar] 3d5 4s1.
Chromium facts
| Symbol | Cr |
|---|---|
| Atomic number | 24 |
| Atomic mass | 51.996 u (g/mol) |
| Category | transition metal |
| Group | group 6 |
| Period | 4 |
| Block | d-block |
| Phase at 20 °C | Solid |
| Electron configuration | 1s2 2s2 2p6 3s2 3p6 4s1 3d5 |
| Noble-gas notation | [Ar] 3d5 4s1 |
| Electrons per shell | 2, 8, 13, 1 |
Bohr model and shells
Chromium has 24 electrons in 4 shells: 2, 8, 13, 1. Full configuration and noble-gas notation are in the table; work out any element or ion with the electron configuration calculator.
Physical and atomic properties
| Melting point | 2180 K (1906.8 °C) |
|---|---|
| Boiling point | 2944 K (2670.8 °C) |
| Density | 7.19 g/cm³ |
| Electronegativity (Pauling) | 1.66 |
| Electron affinity | 65.21 kJ/mol |
| Ionization energies | 652.9, 1590.6, 2987 kJ/mol (1st, 2nd, 3rd) |
| Molar heat capacity | 23.35 J/(mol·K) |
| Discovered by | Louis Nicolas Vauquelin |
Use the atomic mass in the molar mass calculator for any formula containing Cr.
Position in the periodic table
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Frequently asked questions
What is the atomic mass of chromium?
The atomic mass of chromium is 51.996 u, so one mole of chromium atoms weighs 51.996 g.
What is the electron configuration of chromium?
Chromium has 24 electrons: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹ 3d⁵, or [Ar] 3d⁵ 4s¹ in noble-gas notation. Electrons per shell: 2, 8, 13, 1.
Is chromium a metal?
Yes. Chromium is a transition metal.
Where is chromium on the periodic table?
Chromium is in group 6, period 4, in the d-block.
Data: Periodic-Table-JSON (CC BY-SA 3.0); standard atomic weights from IUPAC (abridged). Values in brackets are the mass number of the longest-lived isotope.