There's a pattern. You have to learn about some other quantum numbers, subshells etc..
Btw 4th shell=32 e
5th shell=50
The answer is definitely 4. It has fewer electrons. This is because, whenever the electrons are few, they are positive. Positive electrons are anions, while the negative ones are cations. Hope i helped. Have a nice day.
The atom that is made up of two protons is He. The number of neutrons is also two. The number of electrons matters in the charge. So to make 10 electrons, we add 8 more. hence, 4/2 He 8-.
