Lithium is the first element in Group 1 of the periodic table, a group of elements generally known as the alkali metals. It is the lightest of all metals. Lithium's atomic number is 3, its atomic mass is 6.941, and its chemical symbol is Li.

Properties

Lithium is a very soft, silvery metal with a melting point of 356.97°F (180.54°C), a boiling point of 2,435°F (1,335°C), and a density of 0.534 grams per cubic centimeter. Lithium is extraordinarily soft for a metal with a rating of 0.6 on the Mohs scale, softer even than talc, whose Mohs rating is 1.

Lithium is an active metal, although, as one would predict from its place in the periodic table, not as active as sodium, potassium, and the other alkali metals. For example, it reacts slowly with cold water, releasing hydrogen gas. It does not react with oxygen at room temperature, although it...