Question

How do metals obey the octet rule?

Answer 1

Only the metals in Groups 1 and 2 strictly obey the octet rule.

Explanation:

Group 1 and Group 2 Metals

Metals in Group 1 can lose one `s` electron to achieve an octet of valence electrons, and metals in Group 2 can lose two `s` electrons to achieve an octet.

Transition Metals (Group 3 to Group 11) and Group 12

Transition metals usually have an electron configuration that ends in `ns^2(n-1)d^x`, where `x = 1, 2, … 9`.

They often lose two or three of their valence electrons, but not enough to get back to an `s^2p^6` configuration.

For example, the electron configuration of `"Fe"` is `["Ar"]4s^(2)3d^6`.

`"Fe"` typically loses 2 electrons to form `"Fe"^(2+)`with configuration `["Ar"] 3d^6`, or `"Fe"^(3+)` with configuration `["Ar"] 3d^5`.

Transition metals will often violate the octet rule by using their `d` orbitals for bonding.

They can expand their octet to twelve or more valence electrons.

An example is hexaamminecobalt(III) chloride.

Groups 13 to Group 15 Metals

Aluminium forms compounds such as `"AlCl"_3`, with an incomplete octet.

All the other metals in Groups 12 to 15 can expand their octets.