How Do You Find the Covalent Radius of an Element?

Calculating the Covalent Radius

• 1

  Form a reference table like the one listed in the resources, find the section that addresses your element of interest.

• 2

  Record the homonuclear bond length, the distance between nuclei of two identical elements covalently bonded together. For example, the homonuclear bond distance of H_2 (where 2 is a subscript), is the distance between two hydrogen nuclei whose atoms are covalently bonded together.

• 3

  Divide the homonuclear bond length by 2; this distance is the covalent radius.

Comparing Covalent Radii

• 4

  Instead of calculating the covalent radius of each of the two elements you want to compare, identify the locations of both elements in the periodic table.

• 5

  If the two elements are in the same group, or column, the element farther down the column has the greater covalent radius. Electrons in this lower element occupy higher energy levels, so the electrons are farther away from the nucleus.

• 6

  If the two elements are in the same period, or row, the element farther to the left has the greater covalent radius. This phenomenon has to do with the effective nuclear charge, the charge "felt" by an electron from the nucleus and other electrons, of an atom.