What is Phosphorus? | Definition, Properties, Compounds, & Facts

What is Phosphorus?

Phosphorus is the second element in the fifteenth column of the periodic table. It is classified as non-metallic. The phosphorus atom has 15 electrons and 15 protons, with 5 valence electrons in the outermost shell.

Highlights of Phosphorus:

Symbol P
Atomic Number 15
Atomic Weight 30.97376
Classification Nonmetal
Phase at Room Temperature Solid
Density white: 1.823 grams per cm cubed
Melting Point white: 44.1°C, 111°F
Boiling Point white: 280°C, 536°F
Discovered by Hennig Brandt in 1669

Characteristics and Properties

Phosphorus is a highly reactive element and therefore it is never found on Earth as a free element. Elemental phosphorus occurs in different allotropic forms (different crystal structures), including white, red, purple, and black phosphorus. The two main forms of phosphorus are white and red.

White phosphorus is very reactive and unstable. White phosphorus is slightly yellow in color and very flammable. It will spontaneously ignite when exposed to air. White phosphorus glows in the dark and is also very toxic. Red phosphorus is generally more stable than white phosphorus. It is also less toxic and does not spontaneously ignite when exposed to air. Red phosphorus is made by heating white phosphorus.

Where on Earth is Phosphorus found?

Phosphorus is not found in pure elemental form on Earth, but it is found in many minerals called phosphates. Most commercial phosphorus is produced by mining and heating calcium phosphate. Phosphorus is the eleventh most abundant element in the earth’s crust.

Phosphorus is also found in the human body. It is the sixth most abundant element in the human body.

How is Phosphorus used today?

The main industrial use of phosphorus is in the production of fertilizers. Indeed, phosphorus is an important element for plant growth.

Red phosphorus is used in the manufacture of pesticides and safety matches.

Other uses of phosphorus include baking powder, phosphor bronze alloys, flame retardants, incendiary bombs, and LEDs (light-emitting diodes).

Phosphorus is an important element in the functioning of the human body and is essential for life. It is used in the DNA molecule and is a major component in our bones and teeth. We get phosphorus from foods like beans, nuts, eggs, fish, milk and chicken.

How was it discovered?

Phosphorus was discovered in 1669 by the German alchemist Hennig Brandt. He hoped to create a legendary substance known as the philosopher’s stone. He discovered phosphorus by accident while conducting experiments with urine.

Where does Phosphorus get its name from?

Phosphorus gets its name from the Greek word “phosphorus” which means “light-giver”. Henning Brandt chose this name because the item glows in the dark.


The only stable isotope of phosphorus is phosphorus-31. It has twenty-three known isotopes.

Interesting facts about Phosphorus

It was once a major ingredient in detergents, but phosphates have caused algae growth in rivers and lakes, killing many fish species. Some cleaners today still use phosphates.

Touching white phosphorus can cause severe burns.

Similar to the oxygen, carbon and nitrogen cycle, there is also the phosphorus cycle which is very important for plant and animal life.

Hennig Brandt was the first to be recognized for discovering an element. Black phosphorus looks like graphite powder and conducts electricity even though it is not a metal.

The majority of phosphate rock quarried in the United States comes from Florida and North Carolina.

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