Definition of positive valence
1: the valence of a positively charged ion
2: the number of electrons an atom can give up sodium has a positive valence of 1
Hydrogen has one valence electron, so to be stable, it can gain or lose one electron. When hydrogen meets a more electronegative element, it forms a positive charge (losing one electron), but when it meets a less electronegative element, it forms a negative charge (gaining one electron).