Atomic number 15
Phosphorus
Nonmetal
Quick facts
- Atomic mass
- 30.974
- Group
- 15
- Period
- 3
- State (STP)
- solid
- Electronegativity
- 2.19
- Common ox. states
- -3, +3, +5
Properties
Electron configuration
[Ne] 3s² 3p³
- Ionization energy
- 1011.8 kJ/mol
- Electron affinity
- 72.0 kJ/mol
- Melting point
- 317.30 K (44.2 °C)
- Boiling point
- 553.70 K (280.6 °C)
How it bonds
Phosphorus mirrors nitrogen at first glance — group 15, 5 valence electrons, 3 bonds + 1 lone pair (PH₃). But phosphorus has accessible 3d orbitals, so it routinely forms 5 bonds in PCl₅ and PF₅ — the classic "expanded octet." This is what makes phosphate (PO₄³⁻) the backbone of DNA and ATP.
Where you meet it
- Build Phosphorus trichloridePCl₃
- Periodic Quest challengeunlock card