51121.76SbAntimony
Antimony (Sb) — element 51metalloid · group 15, period 5
Antimony is a chemical element with the symbol Sb and atomic number 51. It is a metalloid in group 15, period 5 of the periodic table (the p-block), with a standard atomic mass of 121.76 u. At room temperature (25 °C) antimony is a solid.
💡 Known for: Used in flame retardants and lead–acid batteries; its mineral stibnite was used as the ancient cosmetic kohl.
# Antimony properties
| Symbol | Sb |
|---|---|
| Atomic number | 51 |
| Atomic mass | 121.76 u |
| Category | metalloid |
| Group | 15 |
| Period | 5 |
| Block | p-block |
| Electron configuration | [Kr] 4d¹⁰ 5s² 5p³ |
| Full configuration | 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p³ |
| Electrons per shell | 2, 8, 18, 18, 5 |
| Protons / electrons | 51 / 51 |
| State at 25 °C | solid |
| Melting point | 903.78 K (630.6 °C, 1167.1 °F) |
| Boiling point | 1860 K (1586.8 °C, 2888.3 °F) |
| Density | 6.685 g/cm³ |
| Electronegativity (Pauling) | 2.05 |
| First ionization energy | 8.64 eV |
| Atomic radius | 133 pm |
| Discovered | known since ancient times |
# Electron configuration of antimony
The electron configuration of antimony is [Kr] 4d¹⁰ 5s² 5p³, written out in full as 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p³. Its 51 electrons fill 5 shells as 2, 8, 18, 18, 5, so the outermost shell holds 5 electrons. As a group 15 element, antimony has 5 valence electrons.
# Related elements
SnTinprevious elementTeTelluriumnext elementNNitrogengroup 15PPhosphorusgroup 15AsArsenicgroup 15BiBismuthgroup 15McMoscoviumgroup 15BBoronmetalloidSiSiliconmetalloidGeGermaniummetalloid
# Antimony FAQ
What is the atomic number of antimony?
The atomic number of antimony is 51: every antimony atom has 51 protons in its nucleus. Its symbol is Sb.
What is the atomic mass of antimony?
The standard atomic mass of antimony is 121.76 u.
What is the electron configuration of antimony?
Antimony's electron configuration is [Kr] 4d¹⁰ 5s² 5p³ (1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p³), with 2, 8, 18, 18, 5 electrons per shell.
Is antimony a metal?
No. Antimony is a metalloid, with properties between those of metals and nonmetals.
What is the melting point of antimony?
Antimony melts at 903.78 K (630.6 °C, 1167.1 °F) and boils at 1860 K (1586.8 °C, 2888.3 °F).
What is antimony used for / known for?
Used in flame retardants and lead–acid batteries; its mineral stibnite was used as the ancient cosmetic kohl.