The ionic radius, metallic radius, and covalent radius of each atom present in a molecule can be used to estimate the bond strength. For suppose, boron's covalent radius is estimated at 83.0 pm, whereas the bond length of B–B in B2Cl4 is given as 175 pm, which is a larger value significantly.This would show that the bond between the two boron atoms is a weak single bond rather. As another example, the metallic radius of rhenium can be given at 137.5 pm, with a Re-Re bond length of 224 pm, present in the Re2Cl8 compound. Using this data, we can conclude that the bond is either a very strong bond or a quadruple bond. This determination method is useful mostly for the covalently bonded compounds.