015Reactive nonmetal · Group 15 · Period 3
Phosphorus
Phosphorus (P) is element 15, a reactive nonmetal in the p-block — group 15, period 3. It is a solid at room temperature with 3 electron shells (2, 8, 5) and an atomic mass of 30.9737619985 u.
- Atomic mass
- 30.97 u
- Phase · STP
- solid
- Melting
- —
- Boiling
- —
- Electronegativity
- 2.19
- Density
- 1.823 g/cm³
Photograph — Jurii, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>, via Wikimedia Commons, source: https://images-of-elements.com/phosphorus.php
Identity
- Atomic number
- 15
- Standard atomic weight
- 30.97 u
- Category
- Reactive nonmetal
- Group
- 15 · Pnictogens
- Period
- 3
- Block
- p-block
- Oxidation states
- +5, +3, -3
Physical properties
- Melting point
- —
- Boiling point
- —
- Density
- 1.823 g/cm³
- Molar heat capacity
- 23.824 J/(mol·K)
- Atomic radius
- 180 pm
- Electron affinity
- 72.037 kJ/mol
Atomic structure
15protons
16neutrons
15electrons
5valence e⁻
- Noble-gas notation
- [Ne] 3s2 3p3
- Full configuration
- 1s2 2s2 2p6 3s2 3p3
- Electrons per shell
- 2, 8, 5
Periodic trends
Where Phosphorus ranks across all 118 elements.
Ionization energies
Energy to remove each successive electron (kJ/mol).
1.0k1
1.9k2
2.9k3
5.0k4
6.3k5
21.3k6
25.4k7
29.9k8
35.9k9
41.0k10
Successive ionization energies (kJ/mol, log scale).
Discovery
- Discovered
- 1669
- Discovered by
- Hennig Brand
- Named by
- —
- Appearance
- colourless, waxy white, yellow, scarlet, red, violet, black