White phosphorus in the context of Flammable

Phosphorus is a chemical element; it has symbol P and atomic number 15. All elemental forms of phosphorus are highly reactive and are therefore never found in nature. They can nevertheless be prepared artificially, the two most common allotropes being white phosphorus and red phosphorus. With P as its only stable isotope, phosphorus has an occurrence in Earth's crust of about 0.1%, generally as phosphate rock. A member of the pnictogen family, phosphorus readily forms a wide variety of organic and inorganic compounds, with as its main oxidation states +5, +3 and −3.

The isolation of white phosphorus in 1669 by Hennig Brand marked the scientific community's first discovery of an element since antiquity. The name phosphorus is a reference to the god of the Morning star in Greek mythology, inspired by the faint glow of white phosphorus when exposed to oxygen. This property is also at the origin of the term phosphorescence, meaning glow after illumination, although white phosphorus itself does not exhibit phosphorescence, but chemiluminescence caused by its oxidation. Its high toxicity makes exposure to white phosphorus very dangerous, while its flammability and pyrophoricity can be weaponised in the form of incendiaries. Red phosphorus is less dangerous and is used in matches and fire retardants.

Red phosphorus is an allotrope of phosphorus. It is an amorphous polymeric red solid that is stable in air. It can be easily converted from white phosphorus under light or heating. Applications include matches and fire retardants. It was discovered in 1847 by Anton von Schrötter.

The Mark 77 bomb (MK-77) is a United States 750-pound (340 kg) air-dropped incendiary bomb carrying 110 U.S. gallons (416 L; 92 imp gal) of a fuel gel mix which is the direct successor to napalm.

The MK-77 is the primary incendiary weapon currently in use by the United States military. Instead of the gasoline, polystyrene, and benzene mixture used in napalm bombs, the MK-77 uses kerosene-based fuel with a lower concentration of benzene. The Pentagon has claimed that the MK-77 has less impact on the environment than napalm. The mixture reportedly also contains an oxidizing agent, making it more difficult to put out once ignited, as well as white phosphorus.

White phosphorus munitions are weapons that use one of the common allotropes of the chemical element phosphorus. White phosphorus is used in smoke, illumination, and incendiary munitions, and is commonly the burning element of tracer ammunition. Other common names for white phosphorus munitions include WP and the slang terms Willie Pete and Willie Peter, which are derived from William Peter, the World War II phonetic alphabet rendering of the letters WP. White phosphorus is pyrophoric (it is ignited by contact with air); burns fiercely; and can ignite cloth, fuel, ammunition, and other combustibles.

White phosphorus is a highly efficient smoke-producing agent, reacting with air to produce an immediate blanket of phosphorus pentoxide vapour. Smoke-producing white phosphorus munitions are very common, particularly as smoke grenades for infantry, loaded in defensive grenade launchers on tanks and other armoured vehicles, and in the ammunition allotment for artillery and mortars. These create smoke screens to mask friendly forces' movement, position, infrared signatures, and shooting positions. They are often called smoke/marker rounds for their use in marking points of interest, such as a light mortar to designate a target for artillery spotters.

Elemental phosphorus can exist in several allotropes, the most common of which are white and red solids. Solid violet and black allotropes are also known. Gaseous phosphorus exists as diphosphorus and atomic phosphorus.

Phossy jaw, formally known as phosphorus necrosis of the jaw, was an occupational disease affecting those who worked with white phosphorus (also known as yellow phosphorus) without proper safeguards. It was most commonly seen in workers in the matchstick industry in the 19th and early 20th centuries. It was caused by white phosphorus vapor, which destroys the bones of the jaw. Modern occupational hygiene practices have since eliminated the working conditions that caused this disease.