Allotropes of phosphorus

Allotropes of phosphorus are distinct structural forms of the element, including white, red, violet, and black phosphorus. Their bonding and crystal structures give them different reactivities and physical properties.

Phosphorus: Phosphorus is a reactive chemical element with atomic number 15 and several elemental structural forms. The allotropes are structures of this element, not different compounds.
White phosphorus: White phosphorus is a waxy, highly reactive form composed of tetrahedral P₄ molecules. Its strained P₄ units help explain its high reactivity.
Red phosphorus in matches: Red phosphorus in matches is a friction-sensitive ignition material placed on the striking surface of safety matches. Its relative stability makes it practical for controlled ignition.
Phosphorus allotrope stability: Phosphorus allotrope stability describes the relative thermodynamic favorability and persistence of its structural forms. Black phosphorus is the thermodynamically stable form under ordinary conditions, while others can persist metastably.
Chemical allotropy: Chemical allotropy is the existence of multiple structural forms of the same element in the same physical state. It names the phenomenon that links these forms.
Red phosphorus: Red phosphorus is a less reactive, polymeric form of phosphorus produced in several related structural varieties. Its extended bonding contrasts with white phosphorus's discrete molecules.
Black phosphorus electronics: Black phosphorus electronics use thin black-phosphorus layers as semiconducting channels in experimental devices. Its tunable band gap and directional transport motivate device research.
White phosphorus toxicity: White phosphorus toxicity is the severe harmful effect caused by exposure to reactive elemental white phosphorus. Its hazards sharply distinguish it from less reactive allotropes.
Phosphorus bonding: Phosphorus bonding describes how phosphorus atoms share or redistribute electrons in molecules and extended structures. Different bonding arrangements underpin the allotropes' distinct structures.
Violet phosphorus: Violet phosphorus is a crystalline allotrope with a complex structure of linked phosphorus atoms. It provides a crystalline structure distinct from the red and black forms.

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Phosphorus trioxideNarrower topic: The starting allotrope affects how phosphorus is handled during oxide preparation.