Its (*) white allotrope has alpha and beta forms depending on the temperature and is the most volatile and reactive allotrope; hence its use as an additive in napalm.
High pressures are usually needed to synthesize this element's black allotrope, while its violet allotrope is sometimes named after Johann Hittorf, who was the first to recrystallize it from molten lead. In its red allotrope, one of its usual tetrahedral bonds is broken, allowing bonding with neighboring tetrahedrons and a more stable structure. Its (*) white allotrope has alpha and beta forms depending on the temperature and is the most volatile and reactive allotrope; hence its use as an additive in napalm. For 10 points, name this chemical element, number 15, which was used in early matches.
High pressures are usually needed to synthesize this element's black allotrope, while its violet allotrope is sometimes named after Johann Hittorf, who was the first to recrystallize it from molten lead.
{phosphorus} [or {P}]