Question
What do you mean by covalent radius?
Solution
The covalent radius (or covalent atomic radius) is defined as half of the distance between the nuclei of two like atoms forming a single covalent bond.
rcov = 1/2 [Internuclear distance between two bonded atoms]
For example, for hydrogen molecule, the internuclear distance between two hydrogen atoms is 74 pm.
rcov = 1/2 [Internuclear distance between two bonded atoms]
For example, for hydrogen molecule, the internuclear distance between two hydrogen atoms is 74 pm.
where 198 pm = Internuclear distance between two chlorine atoms (Cl—Cl) in a molecule of Cl2.
In case of heteronuclear molecules (containing different atoms) such as HCl, the covalent radius may be defined as: “The difference of the distance between the nuclei of two bonded atoms and covalent radius of one of the atoms in a heteronuclear molecule.”
Covalent radius = [Internuclear distance of two bonded atoms] -[Covalent radius of one of the two atoms in heteronuclear molecules]
For example,
Covalent radius of H-atom (in HCl)
= Internuclear distance of HCl - covalent radius of Cl atom
= 136 pm - 99 pm = 37 pm.
