Alkali metals cause explosions and alkaline earth metals display vigorous activity in bulk; to prevent passivation from the formation of metal fluoride layers most other metals such as aluminium and iron must be powdered,[18] and noble metals require pure fluorine gas at 300???450 ??C (575???850 ??F).[21] Some solid nonmetals (sulfur, phosphorus) react vigorously in liquid air temperature fluorine