Why does Br (-) have a larger atomic radius than Rb (+)?

Question

I am trying to understand why Br (-) has a larger atomic radius than Rb (+)... Is there any way to calculate or tell which one is larger?

Answer 1

Br^- and Rb⁺ both have the same electronic configuration of Kr but we have to put on consideration the Br^- has less protons than Rb⁺ so the attraction to nucleus is less and the radius is more

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