Element 51 · Metalloid
Antimony (Sb) — Element 51
Greek anti monos
Antimony (Sb) is a metalloid in Period 5, Group 15 of the periodic table with atomic number 51, standard atomic weight 121.76 u, and ground-state electron configuration [Kr] 4d¹⁰ 5s² 5p³. At standard temperature and pressure it is classified as a solid with 5 valence electrons and common oxidation states -3, +3, +5.
Flame retardants, alloys
What are the atomic properties and physical constants of Antimony?
Reference constants compiled from IUPAC standard atomic weights, the NIST Atomic Spectra Database, and the CRC Handbook.
- Atomic number (Z)
- 51
- Standard atomic mass
- 121.76 u
- Chemical family
- Metalloid
- Ground-state configuration
- [Kr] 4d¹⁰ 5s² 5p³
- Electrons per shell
- 2, 8, 18, 18, 5
- Valence electrons
- 5
- Common ion charges / oxidation states
- -3, +3, +5
- Phase at STP
- Solid
- Pauling electronegativity
- 2.05 Pauling
- First ionization energy
- 834 kJ/mol
- Atomic radius
- 133 pm
- Melting point
- 631 °C
- Boiling point
- 1,587 °C
- Discovery year
- Ancient
- Table coordinate
- Period 5, Group 15
- Radioactivity
- Has stable isotope(s)
How are electrons arranged across Antimony’s shells?
A neutral Antimony atom contains 51 electrons distributed across 5 occupied principal energy shells ([Kr] 4d¹⁰ 5s² 5p³). The table below compares Antimony’s shell occupancy against each shell’s theoretical 2n² capacity.
| Principal Shell (n) | Spectroscopic Letter | Electrons in Sb | Max Shell Capacity (2n²) |
|---|---|---|---|
| n = 1 | K | 2 e⁻ | 2 e⁻ |
| n = 2 | L | 8 e⁻ | 8 e⁻ |
| n = 3 | M | 18 e⁻ | 18 e⁻ |
| n = 4 | N | 18 e⁻ | 32 e⁻ |
| n = 5 | O | 5 e⁻ | 50 e⁻ |
Frequently Asked Questions about Antimony (Sb)
What is the atomic mass and atomic number of Antimony (Sb)?
Antimony (Sb) has atomic number Z = 51 (51 protons in its nucleus) and an IUPAC standard atomic weight of 121.76 u. It sits in Period 5, Group 15 and is classified as a metalloid.
What is the ground-state electron configuration of Antimony?
The neutral ground-state electron configuration of Antimony (Z = 51) is [Kr] 4d¹⁰ 5s² 5p³. Across its 5 occupied principal shells (n = 1 to n = 5), the electrons per shell are 2, 8, 18, 18, 5, with 5 valence electrons participating in bonding.
What are the common ion charges and electronegativity of Antimony?
Antimony commonly forms -3, +3, +5 oxidation states or ion charges in compounds. Its Pauling electronegativity is 2.05 and its first ionization energy is 834 kJ/mol.
When was Antimony discovered and what is it used for?
Antimony was discovered in Ancient (Greek anti monos). Flame retardants, alloys
How does Antimony compare to neighboring elements?
Other metalloid elements: