Lithium has one valence electron. The atomic number of lithium is 3, and its electronic configuration is [He] 2S1. The lone valence electron occupies the second orbit around the nucleus of the lithium atom.
Lithium is a soft metal and has a silvery-white color. It is classified as an alkali metal and is in group 1 and period 2 of the Periodic Table of Elements. Its atomic weight is 6.941 atomic mass units, or grams per mole. It has a melting point of 180.50 degrees Celsius and a boiling point of 1,342 degrees Celsius. Lithium is a solid at room temperature with a density of 0.534 grams per cubic centimeter.