Sodium (Na) has 1 valence electron. This is because sodium has 11 electrons arranged in shells as 2, 8, 1, with the single electron in the outermost shell (the third shell) being the valence electron
. This valence electron is in the 3s orbital according to sodium's electron configuration: 1s22s22p63s11s^22s^22p^63s^11s22s22p63s1
. Sodium is in Group 1 of the periodic table, and elements in this group typically have one valence electron
. The single valence electron explains sodium's chemical reactivity, as it tends to lose this electron easily to form a stable Na+Na^+Na+ ion with a full outer shell
