Lithium

Li. At.wt. 7.02, sp.gr..594, sp.ht..94, valence I. Discovered by Arfvedson 1817. It occurs in petalite, lepidolite, in some mineral springs, in the ash of many plants, especially in those of tobacco and the beet. It is the lightest metal known, of a silvery white color, decomposes water at ordinary temperatures, and burns with an intense white light. It is one of the alkali metals.