Phosphorous (P)

Never found free in nature, phosphorus ([Ne]3s²3p³) (CAS 7723-4-0) is widely available in combination with minerals and is an important component of many organic compounds. It is insoluble in water and highly reactive in air. Available in three allotropic forms; red, black, and white, ordinary phosphorus is a waxy white solid that is colorless and transparent when pure. When exposed to sunlight, or when heated in its own vapor, white phosphorus converts to the red variety, which is relatively stable. The black form resembles graphite and is stable in air.