Red phosphorus

Red phosphorus is a special form of the element phosphorus. It is usually a red solid that does not catch fire easily in air, making it safer to handle than another form called white phosphorus.

People first made red phosphorus by shining sunlight on white phosphorus or by heating it. This discovery happened in 1847 by a scientist named Anton von Schrötter. By heating red phosphorus in a vacuum, it can change into a crystalline form called violet or Hittorf’s phosphorus, named after another scientist.

Red phosphorus is very useful. It is a key ingredient in safety matches, helping them light only when struck against a special surface. It is also used in fire retardants, materials that help prevent things from catching fire too easily.

Amorphous red phosphorus

Amorphous red phosphorus is a type of phosphorus with a chain-like structure. It does not dissolve in most liquids. It can be made by shining sunlight or applying heat to white phosphorus. Unlike white phosphorus, amorphous red phosphorus is more stable and does not react easily. It also has properties that let it work as a semiconductor.

Crystalline red phosphorus

Hittorf's phosphorus, also called violet phosphorus, is a type of red phosphorus that has a crystal shape. It can be made by heating red phosphorus in a vacuum with a helper called iodine. Violet phosphorus behaves a bit differently from regular red phosphorus—it can catch fire if hit in the air, but it won’t catch fire when touched to bromine at normal temperatures.

Another form is fibrous red phosphorus, made in the same way as violet phosphorus. In fibrous red phosphorus, the phosphorus chains line up specially, and it can help in certain chemical reactions.

Applications

Red phosphorus helps make things safer from fires. It makes a special acid that stops flames from spreading when mixed with some plastics. This helps keep many everyday products from catching fire easily.

You can also find red phosphorus on the strip you rub against to light a match. This makes matches safer and easier to use. It is also used to make important chemicals for different industries, though some of these uses are carefully watched.