Phosphorus

Phosphorus is a chemical element with the symbol P and atomic number 15. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly reactive, phosphorus is never found as a free element on Earth.

What the numbers say

At standard temperature and pressure Phosphorus is a solid, sitting in period 3, group 15 of the p-block.

Its melting point of 317 K (44 °C) is the 92nd highest of the 110 elements with a measured value — mid-range among the elements.

At 1.823 g/cm³ it is the 79th densest of 96 elements with a quoted density.

Pauling electronegativity is 2.19. Paired with oxygen (3.44) that is a difference of 1.25, which puts the bond polar covalent — oxides here tend to be semiconducting or refractory rather than salt-like.

In the solid state it takes a simple triclinic structure.

It is reported in 8 oxidation states (-3, -2, -1, 1, 2, 3, 4, 5), which sets how many distinct compounds and phases it can form.

First identified in 1669.

Crystal structure

Check it against computed structures

The structure search queries the Materials Project, OQMD and the Open Materials Database for computed crystal structures containing P — with DFT formation energy, hull stability and band gap where the provider publishes them.