ElementsWhat is antimony?
Antimony is a silvery, brittle element known since ancient times. Its black sulfide was used as eye make-up in the ancient world.
What is antimony used for?
Flame retardants, hardening lead in batteries, and some semiconductors.
Where the name comes from
From Greek words usually explained as 'not alone'. The symbol Sb comes from stibium, its Latin name.
Key facts
- Symbol
- Sb
- Atomic number
- 51
- Atomic mass
- 121.760 u
- Family
- Metalloid
- Period
- 5
- Group
- 15
- Block
- p
- State at room temperature
- Solid
- Melting point
- 630.6 °C (903.78 K, 1,167 °F)
- Boiling point
- 1,587 °C (1,860 K, 2,888 °F)
- Density
- 6.68 g/cm³
- Electrons per shell
- 2, 8, 18, 18, 5
- Electron configuration
- [Kr]5s2 4d10 5p3
- Common oxidation states
- +5, +3, -3
- Electronegativity (Pauling)
- 2.05
- First ionisation energy
- 8.64 eV
- Electron affinity
- 1.07 eV
- Atomic radius (van der Waals)
- 206 pm
- Discovered
- Known since ancient times
Place in the periodic table
Antimony is element number 51. It sits in period 5 (row 5) of the periodic table, in group 15 (column 15), and belongs to the p-block. Just before it comes tin (50), and just after it comes tellurium (52). In the same column, arsenic is above it and bismuth is below it. Elements in one column tend to behave alike.
Family: Metalloids.
Physical properties
At room temperature antimony is a solid. It melts at 630.6 °C and boils at 1,587 °C, so it stays liquid over a range of 956 degrees. Its density is 6.68 grams per cubic centimetre, so a one-litre block would weigh about 6.68 kilograms. By density it ranks 54th among the 96 elements with a measured value.
Inside the atom
An atom of antimony has 51 protons in its nucleus and, when neutral, 51 electrons around it. The electrons are arranged in 5 shells: 2, 8, 18, 18, 5. The outermost shell holds 5 electrons. Written in full, the electron configuration is [Kr]5s2 4d10 5p3.
Its electronegativity on the Pauling scale is 2.05. This number shows how strongly an atom pulls shared electrons towards itself: fluorine, the strongest, is 3.98. Removing one electron from an atom takes 8.64 electronvolts (about 834 kilojoules per mole). One mole of antimony weighs 121.760 grams, so a single gram contains about 4.95 × 1021 atoms.
The ring picture is a simple model that only counts the electrons in each shell. Real atoms do not look like this.
Next steps
- Work out the weight of a compound that contains antimony with the molar mass calculator.
- Compare it with every other element in the sortable list.
- Test yourself with the symbol quiz.
Figures on this page are from PubChem (U.S. National Library of Medicine), as downloaded on 11 November 2026. See About and data sources.