Red phosphorus

Red phosphorus is a special form of the element phosphorus. It is usually a red, amorphous 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 polymeric form of phosphorus, meaning its structure is made of connected chains. It does not dissolve in most solvents and can be made by exposing white phosphorus to sunlight or heat. Unlike white phosphorus, amorphous red phosphorus is much more stable and does not react as easily. It also has properties that allow it to act as a semiconductor.

Crystalline red phosphorus

Hittorf's phosphorus, also called violet phosphorus, is a crystalline form of red phosphorus. It can be made by heating red phosphorus in a vacuum with a special helper called iodine. Violet phosphorus acts a little differently from regular red phosphorus—it can catch fire when hit in the air, but it does not catch fire when touched to bromine at room temperature.

Another form is fibrous red phosphorus, which is also made along with violet phosphorus using the same method. In fibrous red phosphorus, the phosphorus chains line up in a special way, and it can help in special chemical reactions like a photocatalyst.

Applications

Red phosphorus is used to make materials safer from fires. It works by creating a special acid that helps stop flames from spreading when mixed with certain plastics. This makes many everyday products less likely to catch fire.

It is also found on the strip you rub against to light a match. This makes matches safer to use and produce. Additionally, red phosphorus helps create important chemicals used in different industries, though some of these uses are carefully controlled.