Periodic Table
15
P
30.974
Phosphorus
NonmetalAllotropes white (reactive, P₄) & red; white P glows (chemiluminescence).
Electronic Configuration
[Ne] 3s² 3p³or1s² 2s² 2p⁶ 3s² 3p³
Electron shells
2e⁻n=1
8e⁻n=2
5e⁻n=3
Properties
Atomic number
15
Atomic mass
30.974 u
Category
Nonmetal
Block / Group / Period
p · 15 · 3
Valence electrons
5
Oxidation states
-3, +3, +5
Electronegativity
2.19
Atomic radius
98 pm
Ionization energy
1012 kJ/mol
Electron affinity
72 kJ/mol
Melting point
317 K / 44 °C
Boiling point
553 K / 280 °C
Density
1.82 g/cm³
State at 25 °C
solid
JEE / NEET notes
- White P (P₄): reactive, toxic, glows; stored under water.
- Red P: polymeric, stable, less reactive.
- Forms pπ–dπ bonds (unlike N).
- H₃PO₃ is dibasic, H₃PO₄ is tribasic.
Ores & extraction
Ores: Phosphorite, Apatite [Ca₅(PO₄)₃(F/Cl)]
Uses
Fertilisers · Matches (red P) · Detergents · Phosphoric acid
Important compounds
H₃PO₄P₄O₁₀PCl₅Ca₃(PO₄)₂
Personal Notes
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