Sodium (Na) has 1 valence electron.
The electron configuration of sodium is 1s22s22p63s1. Valence electrons are the electrons in the outermost shell of an atom, which are involved in chemical bonding. In the case of sodium, the outermost shell is the third shell (n=3), and it contains only one electron in the 3s orbital. Therefore, sodium has only 1 valence electron. This explains why sodium readily loses this one electron to form a +1 ion (Na+), achieving a more stable electron configuration.
