Valence Electrons and the Periodic Table

Helium only has two

valence

electrons

, so what happens in this column is that most of these have eight. neon has one argon, as does krypton, xenon and radon, but then there's helium which only has two, but regardless of whether it's necessary, I mean, if you have eight or two, if you're in this column, your

valence

shell is totally full, so here it is full with eight, here it is full with eight and here it is full with two, but they are all full and there are no empty holes in the shells, so as an example I am going to use neon which has eight so one two three four and now we go clockwise five six seven eight eight valence

electrons

for most of these guys, but remember that helium only has two valence electrons but they all have valence shells that are completely filled with no empty spaces, so this sums up everything we talked about.

Each atom in this column has one valence electron. Each atom in this column has two valence electrons. Then we skip this middle section and get three. four five six seven and eight, so if you know which of these columns a particular atom is in, you can calculate how many valence electrons it has