Chromium (Cr)
Transition metal · d-block · period 4 · group 6
Hard, brittle, blue-white metal that takes a mirror polish.
Chromium (symbol Cr) is chemical element number 24, a transition metal in group 6, period 4 of the periodic table. Its standard atomic weight is 51.996 and its electron configuration is [Ar] 3d5 4s1. At room temperature it is a solid. Its name is Greek for 'colour' — its compounds are red, orange, yellow, green and violet.
Properties
| Atomic number | 24 |
|---|---|
| Atomic mass | 51.996 |
| Category | Transition metal |
| Block | d-block |
| Group · Period | 6 · 4 |
| Electron configuration | [Ar] 3d5 4s1 |
| Electrons per shell | 2, 8, 13, 1 |
| State at 25 °C | solid |
| Melting point | 2180 K |
| Boiling point | 2944 K |
| Density | 7.15 g/cm³ |
| Electronegativity (Pauling) | 1.66 |
| Radioactive | No |
| Origin | primordial |
| Discovered | 1794 · Louis-Nicolas Vauquelin |
Key facts about Chromium
- Its name is Greek for 'colour' — its compounds are red, orange, yellow, green and violet.
- Chromium plating gives the bright, hard, rust-proof finish on taps and car trim.
- Adding chromium to steel makes stainless steel.
- Rubies and emeralds owe their colours to trace chromium.
What Chromium is used for
Stainless steel, chrome plating, pigments, leather tanning, wood preservatives.
Where it sits in the periodic table
Chromium is in group 6, period 4, of the d-block. Its electron configuration [Ar] 3d5 4s1 means its outermost shell holds 1 electron, which is what places it here and explains much of its chemistry. See Chromium on the interactive table →
Chromium — frequently asked questions
What is Chromium used for?
Stainless steel, chrome plating, pigments, leather tanning, wood preservatives.
Is Chromium radioactive?
No. Chromium has at least one stable isotope and is not radioactive.
What is the electron configuration of Chromium?
Chromium has the electron configuration [Ar] 3d5 4s1, which is 2, 8, 13, 1 electrons per shell.
What group and period is Chromium in?
Chromium is in group 6, period 4, in the d-block. Its outer shell holds 1 electron.
Who discovered Chromium?
Chromium was discovered in 1794 by Louis-Nicolas Vauquelin.