Originally Posted by redgoober4life
What is also more confusing to this is that even though Sc does have one electron in the 3d subshell, it has one more proton. More protons=more internal pull on the electrons which would decrease the size. So I don't know if having more electrons would necessarily make it larger overall. I don't know though
If the 3s level is full, the electrons tend to "shield" the protons from the electrons in the next higher energy level shell, so the protons have less pull on the electrons in the 3d level.