Now if we look at these orbitals and subshells what we'll find is that the ones on the inside are going to be, or the inner electrons are going to be called core electrons.
The one thing that you have to add to that is that once we fill up one of these orbitals or subshells, it's going to shield the electrons on the outside from those on the inside.
Well remember as we're going across a subshell, let's say we're going across this p block right here, as we go across we're increasing the number of protons.