An atom has the following electron configuration. 1s^2 2s^2 2p^6 3s^2 3p^4 how any valence electrons does this atom have?

6.

Explanation:

The valence electrons are those in the outer  shells  3s and 3p,  so it is 2 + 4 = 6.

the number of valence electrons for each molecule or ion is shown beneath the structure. remember hydrogen will not have more than two electrons. this hydrogen is part of a covalent bond (sharing two electrons). a double bond here would cause hydrogen to share four electrons with phosphorus.