# How do metals obey the octet rule?

Dec 17, 2013

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 $n {s}^{2} \left(n - 1\right) {d}^{x}$, where x = 1, 2, … 9.

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

For example, the electron configuration of $\text{Fe}$ is $\left[\text{Ar}\right] 4 {s}^{2} 3 {d}^{6}$.

$\text{Fe}$ typically loses 2 electrons to form ${\text{Fe}}^{2 +}$with configuration $\left[\text{Ar}\right] 3 {d}^{6}$, or ${\text{Fe}}^{3 +}$ with configuration $\left[\text{Ar}\right] 3 {d}^{5}$.

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 ${\text{AlCl}}_{3}$, with an incomplete octet.

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