Phosphorus

01 / A closer look

Meet Phosphorus

Phosphorus has atomic number 15: every atom of this element contains 15 protons. It belongs to period 3, group 15 of the periodic table.

In a neutral atom, the number of electrons equals the number of protons. Isotopes of this element share the same atomic number but have different neutron counts.

02 / Physical properties

Melting point

317.3 K

White phosphorus; other allotropes differ

Boiling point

553.7 K

White phosphorus; other allotropes differ

Density

1.823 g/cm³

White phosphorus; other allotropes differ

Atomic weight

30.974 ± 0.001

Melting points, boiling points and densities follow RSC fact boxes. Density is referenced to room temperature; consult the source for pressure and allotrope details. These are reference values, not a claim that every value was experimentally measured. Atomic weights follow CIAAW.

Physical-property source: Royal Society of Chemistry ↗ · Reviewed 24 September 2026

Standard atomic weights follow CIAAW 2024 (abridged). Brackets show an isotope mass number from IUPAC 2022, not a standard atomic weight.

03 / Atomic structure

Atomic structure

Electron configuration

[Ne]3s2 3p3

Oxidation states

+5, +3, -3

Electronegativity · Pauling

2.19

First ionisation energy

10.487 eV

Atomic radius

180 pm

04 / Where it is found

Where it is found

Phosphate rock, including apatite minerals.

Production and export figures depend on the commodity and reporting year. No comparable country quantities have been included for this element in this edition.