Ionic radii

In my words: for anions that gain electrons as the ionic radii increases compared to the atomic radii, for cations they lose electrons as the ionic radii decreases.

Definition: The ionic radius is the measure of an atom's ion in a crystal lattice. Values for ionic radius are difficult to obtain and tend to depend on the method used to measure the size of the ion. A typical value for an ionic radius would be from 30 pm (0.3 Å) to 200 pm (2 Å). Ionic radius may be measured using x-ray crystallography or similar techniques.