Antimony
A brittle metalloid used in flame retardants and alloys.
Inside the Antimony atom
Switch between Bohr and Quantum Cloud modes to compare a simple teaching model with a more realistic probability-based view, and follow the guided tour to explore the Antimony atom step by step.
Electron configuration
[Kr] 4d10 5s2 5p3
A neutral Antimony atom has 51 electrons (equal to its proton count). Choosing a different isotope above changes only the neutron count.
Shell distribution
Electrons fill inner shells before outer ones; the outermost (valence) shell drives the element's chemistry.
Physical & atomic properties
- State (room temp)
- Solid
- Melting point
- 904 K (631 °C)
- Boiling point
- 1860 K (1587 °C)
- Density
- 6.685 g/cm³
- Electronegativity
- 2.05 Pauling
- Atomic radius
- 145 pm
- 1st ionization energy
- 834 kJ/mol
- Category
- Metalloids
Discovery & naming
- Discovered
- Antiquity
- Discovered by
- Known since antiquity
- Origin of name
- Greek 'anti monos', meaning not alone.
Notable uses
Flame retardants, lead alloys, and semiconductors.
Where Antimony comes from
Several comparable sources
Both slow neutron capture in dying stars and rapid capture in explosive events contribute meaningfully.
Simplified origin map — many elements form through more than one astrophysical pathway.
Summary
- Atomic number
- 51
- Atomic mass
- 121.76
- Category
- Metalloids
- Group · Period
- 15 · 5
- Block
- p-block
- Shells
- 2 · 8 · 18 · 18 · 5