Question

three different atoms or atomic cations with 20 electrons

Answer 1

@AZ

Answer 2

nevermind I found it lol

Answer 3

20 electrons

what neutral element would have 20 electrons?
hint: it's going to have 20 protons so look at your periodic table

and cations that would have 20 electrons are going to have more than 20 protons but they've lost an electron or two hence why they have a positive charge

so if they have 21 protons and 21 electrons but lose one electron, how many electrons does it have now?
what element is that?

remember: if the number of protons change, then the entire element changes
if the number of electrons changes, then you're dealing with ions and it can either be an anion (if it gained an electron) or a cation (if it lost an electron)