What is the relationship between atomic radius and electronegativity?

The relationship between atomic radius and electronegativity is generally inverse: as the atomic radius increases, electronegativity tends to decrease, and vice versa.

Atomic radius refers to the distance from the nucleus of an atom to the outermost electron shell. When the atomic radius is larger, the outer electrons are farther away from the nucleus, experiencing weaker attraction, which leads to decreased electronegativity.

Electronegativity, on the other hand, is a measure of an atom's tendency to attract electrons towards itself when participating in a chemical bond. Atoms with smaller radii have a stronger hold on their electrons due to the stronger nuclear pull, resulting in higher electronegativity.

However, there are exceptions to this trend, notably involving the transition metals and certain anomalies within different groups and periods of the periodic table. Nonetheless, the general trend of increasing atomic radius corresponding to decreasing electronegativity and vice versa is a useful guideline.