Cation vs. Anion Radii Comparison

Size Order: $$\text{Size Order: Anion} > \text{Neutral Atom} > \text{Cation}$$

Concept: Removing electrons decreases electron-electron repulsion and increases $$Z_{\text{eff}}$$ causing contraction (cation), while adding electrons increases mutual repulsion and expands the cloud (anion).

Notation:

• $$\text{Anion}$$ = Negatively charged ion;
• $$\text{Neutral Atom}$$ = Uncharged base element;
• $$\text{Cation}$$ = Positively charged ion.