Name: lithium
Symbol: Li
Atomic number: 3
Atomic weight: [ 6.941 (2)] g m r
Group in periodic table: 1
Group name: Alkaline metal
Period in periodic table: 2
Block in periodic table: s-block
CAS registry ID: 7439-93-2
Lithium is a Group 1 (IA) element containing just a single valence electron (1s22s1). Group 1 elements are called "alkali metals". Lithium is a solid only about half as dense as water. A freshly cut chunk of lithium is silvery, but tarnishes in a minute or so in air to give a grey surface.