Phosphorus (P)

Phosphorus properties

Atomic number

15

Atomic mass

30.974 u

Category

Reactive nonmetal

Group

15

Period

3

Block

p-block

State at room temp.

Solid

Electronegativity

2.19

Melting point

317.3 K (44.2 °C)

Boiling point

553.7 K (280.6 °C)

Density

1.823 g/cm³

Valence electrons

5

Common charges

−3

Oxidation states

+5, +3, −3

Atomic radius

180 pm

Ionization energy

10.487 eV

Electron affinity

0.746 eV

Radioactive

No, has stable isotopes

Discovered

1669

Phosphorus electron configuration

The electron configuration of Phosphorus (P) is [Ne] 3s2 3p3. Its 15 electrons are arranged in shells as 2, 8, 5.

Protons, neutrons and electrons in Phosphorus

A neutral Phosphorus atom has 15 protons and 15 electrons. Most Phosphorus atoms have about 16 neutrons: the atomic mass rounded to 31, minus the atomic number 15.

Neutrons are approximate: atoms of the same element can have different numbers of neutrons (isotopes). Atomic number and mass

How many valence electrons does Phosphorus have?

5

Phosphorus has 5 valence electrons in its outermost shell, shell 3. These are the electrons involved in chemical bonding.

See every element: Periodic table with valence electrons

Phosphorus orbital diagram

Each box is an orbital that holds up to two electrons with opposite spins (↑↓). The inner shells are the same as the noble gas in brackets. How to write electron configurations

Molar mass of Phosphorus

30.974 g/mol

One mole of Phosphorus atoms (6.022 × 10²³ atoms) has a mass of 30.974 grams. Use this value to convert between grams and moles.

Compounds containing Phosphorus

Phosphorus facts

• Phosphorus gets its name from the Greek for 'light-bearer', because white phosphorus glows faintly in the dark as it reacts with oxygen.
• White phosphorus can catch fire on its own in air, so it is stored under water.
• Phosphorus (P) has atomic number 15 and is a solid at room temperature. It was discovered in 1669.

Position in the periodic table

Phosphorus is element 15, in period 3 and group 15 of the periodic table, in the p-block.

All nonmetals

Uses of Phosphorus

Phosphorus is mined as phosphate rock, and most of it is turned into fertilizers that supply this essential plant nutrient. Phosphoric acid gives cola drinks their tang and is used to treat metal surfaces against rust, and phosphates are added to some foods and to animal feed. Red phosphorus is part of the striking surface on boxes of safety matches.

Who discovered Phosphorus?

German alchemist Hennig Brand discovered phosphorus in Hamburg in 1669 while boiling down large amounts of urine in search of the philosopher's stone. The glowing substance he obtained was white phosphorus.

Where does the name come from?

Phosphorus comes from the Greek phosphoros, meaning 'light-bearer', from phos, 'light', and pherein, 'to carry'. The name refers to the eerie glow that white phosphorus gives off in the dark as it reacts with air.

Discovery timeline