Covalent radii are obtained from experimentally determined distances between bonded atomic nuclei in molecules. By comparing numerous molecules, an average radius for each type of atom is obtained, and such values are used to determine atomic sizes in the view.

All covalent radii are drawn to the same relative scale to enable comparison of radii of various atoms within the same molecule and between pairs of molecules in the database.

HCl vs. HI

The numerical values for the covalent radii in angstroms are:
Hydrogen……0.37
Chlorine……..0.99
Iodine………..1.33
The graphics are scaled to size.

Covalent Radii

This graphic shows the periodic trends for covalent radii of several atoms in the same period and several atoms in the same group.