00:01
In this question, we were determining the number of valence electrons that each element has.
00:07
So the valence electrons are considered those that do not fill up the orbital in which to make a non -reactive species, a nobel gas.
00:21
So it's basically, we'll see, that everything except for this row here would have valence electrons.
00:27
So starting with a, we have b -a, which is number 56 down here.
00:32
So it's a nobel gas.
00:35
The closest one for it is that car -54xe.
00:40
And so we just count the number away from that.
00:44
So one here, two here.
00:46
So it has two valence electrons.
00:51
We do the exact same thing for cs, because it's ba's neighbor.
00:55
But it only has one position over.
00:58
So it only has one extra, one valence electron, instead of two...