Within nonmetals, ions that have more electrons tend to be bigger than ions that have fewer additional electrons why?

Nonmetals that have less electrons have less shielding (electrons between valence electrons and nucleus) so the nucleus has more pull on the valence electrons so it pulls on these electrons and this kinda squishes the electron down so it's smaller. With more electrons between valence electrons and nucleus there isn't as much force pulling these electrons toward nucleus so they tend to be bigger