In which direction does electron affinity typically increase in the periodic table?

Electron affinity typically increases from left to right across a period and from bottom to top within a group on the periodic table. This trend can be attributed to the arrangement and behavior of electrons in atoms.

As you move from left to right across a period, the effective nuclear charge experienced by the outer electrons increases because the number of protons in the nucleus increases while shielding remains relatively stable. This greater nuclear charge attracts additional electrons more effectively, resulting in a higher electron affinity.

In addition, as one moves up a group, the atomic radius decreases. Electrons are closer to the nucleus and experience less shielding, which enhances the attraction between the nucleus and the incoming electron. Therefore, the combination of these two factors explains why the trend for electron affinity increases both left to right and bottom to top in the periodic table.

This understanding is crucial for predicting how different elements will behave in chemical reactions, particularly in gaining electrons to form anions.