The oxidation number of all metals on the periodic table have a positive (+) charge. which of these best explains why? a) metals are known to add protons to their nuclei causing them to become positively charged. b) all metals lose one or more valence electrons to become stable, giving them a positive oxidation number. c) all metals gain one or more valence electrons to become stable, giving them a positive oxidation number. d) metals are known to lose protons and add neutrons to their nuclei causing them to become positively charged.