Phosphorus · element 15
The element that glows in the dark, strikes a match, builds your bones and holds your DNA together
Key facts
Phosphorus was the first element discovered by a person whose name we know, and it arrived with a sense of theatre. In 1669 a German alchemist boiled down vast quantities of urine and obtained a waxy solid that glowed in the dark and burst into flame in air. He named it after the Greek for light-bearer.
Phosphorus comes in several very different forms. White phosphorus is soft, poisonous and catches fire on its own. Red phosphorus is stable and lives on the side of matchboxes. Black phosphorus is flaky and conducts electricity. In our bodies the element exists as phosphate, the group of atoms that links the strands of DNA, stores energy as ATP and hardens bone and teeth.
Where it is found
Phosphorus is never found free in nature because it reacts too readily with oxygen. It occurs as phosphate minerals, chiefly the apatite family of calcium phosphates. Sedimentary phosphate rock, laid down on ancient seabeds from the remains of marine life, is mined on an enormous scale. Morocco and Western Sahara hold the largest reserves by a wide margin, with China, the United States, Russia and Jordan also significant producers.
Phosphorus is roughly the eleventh most abundant element in the crust at about 0.1 per cent. Living things concentrate it. Bones and teeth are mostly calcium phosphate, and guano, the accumulated droppings of seabirds, was so rich in phosphate that islands were fought over and stripped bare in the nineteenth century.
How it was discovered
Hennig Brand, a merchant and self-taught alchemist in Hamburg, was searching for the philosopher's stone. Around 1669 he let buckets of urine stand until they putrefied, boiled them to a paste, heated the residue fiercely and passed the vapours through water. What condensed was a white waxy substance that glowed with a cold green light in the dark.
The glow made phosphorus famous across Europe. Robert Boyle in London worked out how to make it independently in 1680 and studied it carefully. In 1769 the Swedish chemists Johan Gottlieb Gahn and Carl Wilhelm Scheele found that bone was a rich source, and phosphorus production shifted from urine to bones.
What we use it for
About nine tenths of all mined phosphate goes into fertiliser. Phosphorus is one of the three main plant nutrients alongside nitrogen and potassium, and crop yields collapse without it. Phosphate rock is treated with sulfuric acid to make superphosphate, or with more acid to make the concentrated fertilisers used worldwide.
Elemental phosphorus and its compounds have many smaller roles. Red phosphorus coats the striking strip of safety matches. Phosphoric acid gives cola drinks their sharp taste and is used in rust removal. Phosphorus compounds appear in flame retardants, pesticides, steel making and lithium iron phosphate batteries. White phosphorus is used in military smoke munitions.
Reading the numbers
The data has no single melting or boiling point for phosphorus, because the different forms behave so differently. White phosphorus melts at about 44 degrees Celsius, so a warm room could soften it, and it boils at about 280 degrees. The density listed, 1.82 grams per cubic centimetre, describes white phosphorus; black phosphorus is denser at about 2.7.
The configuration [Ne] 3s2 3p3 gives phosphorus five outer electrons, the same pattern as nitrogen above it in group 15. Unlike nitrogen, phosphorus does not form a stable triple-bonded pair. Its atoms are larger, so they prefer to form three single bonds and build up chains, cages and layers. This is why phosphorus has so many solid forms while nitrogen is a simple gas. Its electronegativity of 2.19 is much lower than nitrogen's 3.04, and phosphorus can form five bonds, as in phosphoric acid and phosphate, which nitrogen cannot.
Safety and the environment
White phosphorus is one of the most dangerous common chemicals. It ignites spontaneously in air at around 30 degrees Celsius, sticks to skin and burns deeply, and is highly toxic, with a lethal dose well under a gram. Workers in nineteenth-century match factories developed phossy jaw, a rotting of the jawbone, which led to the ban on white phosphorus matches.
The environmental problem is excess phosphate. Fertiliser runoff and sewage feed algae in lakes and rivers, causing blooms that use up oxygen and kill fish. Unlike nitrogen, phosphorus has no atmospheric reservoir: once it washes to the sea it is gone for millions of years. Phosphate rock is a finite resource concentrated in a few countries, and recovering phosphorus from sewage and manure is becoming an important goal.
Did you know?
- Phosphorus was the first element discovered by a named individual, Hennig Brand, in about 1669.
- White phosphorus glows in the dark because it reacts slowly with oxygen in the air, not because it stores light.
- The word phosphorescence was named after phosphorus, even though the glow of phosphorus is a different process.
- The backbone of every DNA molecule is a chain of phosphate groups.
- About 85 per cent of the phosphorus in your body is in your bones and teeth as calcium phosphate.
- The head of a safety match contains no phosphorus. The red phosphorus is in the striking strip on the box.
More in the non-metals
Column-mates come first, since elements in one column have outer electrons arranged in a similar way and tend to behave alike; the rest are the nearest neighbours in the family.
See all 7 non-metals on one page, or browse all 118 elements.
Compare Phosphorus with another element
Each comparison has a side-by-side data table and a plain-English summary of the differences.
Frequently asked questions
Why does phosphorus glow in the dark?
White phosphorus reacts slowly with oxygen in the air, and the reaction releases energy as a faint green light. This is chemiluminescence, light from a chemical reaction. It is not the same as the glow-in-the-dark stickers that store light and release it later, even though that effect was named after phosphorus.
Is phosphorus dangerous?
White phosphorus is very dangerous: it catches fire on contact with air, causes deep burns and is highly poisonous. Red phosphorus is much safer and is used on matchboxes. The phosphates in food, bones and fertiliser are stable compounds and are essential to life.
What is phosphorus used for?
About 90 per cent of mined phosphate becomes fertiliser, with animal feed next. Smaller amounts go into matches, detergents, cola drinks, flame retardants, steel making and lithium iron phosphate batteries.
Why is phosphorus important for the body?
Phosphate forms the backbone of DNA, stores and delivers energy as ATP, and makes up the mineral of bones and teeth along with calcium. Every cell membrane is built from phospholipids. The body gets all the phosphorus it needs from a normal diet, especially dairy, meat, fish and grains.
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Written by Anthony. Updated September 2026. Numerical data from Periodic-Table-JSON (CC BY-SA), cross-checked against the Phosphorus reference article. Spotted an error? Tell us.