How does the octet rule determine the charge of an ion?
Monatomic ions are atoms that have fulfilled their octets by either gaining or losing electrons.
Only metals in Groups 1, 2, and 13 follow the octet rule. They can lose one, two, or three electrons, respectively, to achieve their octets. This gives them charges of +1, +2, and +3.
The octet rule applies only to filling s and p orbitals. Transition metals (Groups 3 to 12) have an electron configuration that involves d orbitals. They do not follow the octet rule.
Nonmetals in Groups 15 to 17 can achieve an octet by gaining three electrons, two electrons, or one electron. This gives them charges of -3, -2, and -1.
This concept is explained in the following video:
Video from: Noel Pauller