Lithium (Li) has 1 valence electron.
Explanation: Lithium is an alkali metal with the atomic number 3. Its electron configuration is 1s2 2s1. The outermost shell, which is the second shell (2s1), contains only one electron. This single electron in the outermost shell is what we refer to as the valence electron. Valence electrons are important because they determine how an element will react chemically with other elements.