How does the octet rule relate to alkali metals?

Alkali metals have one valence electron so they will want to donate an electron in order to satisfy their octet.

The states that when a metal and nonmetal ion wants to form a bond together, one will donate electrons and one will accept electrons in order to have 8 (8 electrons in its outer shell).

Let's look at Na (sodium. The sodium ion has one electron in its outer shell. Notice how sodium is in period 3. That means it has three shells. The second shell is completely filled with 8 electrons, and the third shell has one electron. Na can either donate one electron or accept 7 electrons. If sodium donates one electron then there will only be two shells filled with electrons. BUT, the second shell will have 8 electrons in its "new" outer most shell which is now the second shell.

Having 8 electrons in the outer most shell will make sodium more stable. The alternative is to give sodium 7 electrons. Giving 7 electrons is unfavorable and requires too much energy. It is much easier just to donate 1 electron than to require another ion to give 7 electrons to sodium.

Therefore alkali metals will want to donate one electron in order to have a filled shell.