Valence Electrons, i was wondering how do you figure out the # of electrons from 3s-4d.?

I understand that something like lithium has 3 electrons and one valence electron because theres one in the 2 level. Now if you got something in the 3d level do you consider the 3 level only or the 4s as well? I hope you guys understand what im trying to say. Help PleaseValence Electrons, i was wondering how do you figure out the # of electrons from 3s-4d.?
Valance electrons are only the outermost electrons of an atom. If there are any electrons the 4 level, then you only count those. No need to count the ones in the 3 level.





1s2 2s2 2p6 3s2 3p6 4s2 3d10


if the electron configuration is like this ( sorry no superscript), you still only count the electrons on the 4th energy level, even though the 3d level comes after it.





[the electrons fill up levels by energy efficiency, not by numerical order, that is why the 4s level comes before 3d]





i hope this helps...