Question

Consider sodium, which has an atomic number of 11 and an atomic mass of 23. How many valence electrons does it have?

Answer 1

In which Group of the Periodic Table, which vertical column, does sodium lie?

Explanation:

This should be pretty obvious. And the number of this Group gives the number of valence electrons...

Answer 2

`1`

Explanation:

Sodium has the electron configuration of `[Ne]3s^1`. Therefore, its outermost shell is `n=3` and has one electron. So sodium has one valence electron.

Alternatively, as anor277 stated, one could use the group number (without counting the transition metals) to find the number of valence electrons of an element.