Atomic Radius

It is possible to estimate the radii of atoms and characteristic bonding situations by observing the distances between atoms and molecules. In any given group of the periodic table, for example Group VI-A, the atomic radius increases as we move downward. As we move from left to right in any row, the atomic radius generally tends towards smaller values. This occurs because the effective nuclear charge acting on the outermost electrons is increasing. As we proceed across the first long row of the table, in which electrons are being added to the valence she1l D orbitals of the metals, we see an overall decrease in radius as a result of increasing effective nuclear charge.