Although all covalent bonds
involve the sharing of electrons they widely differ in the degree of sharing and based on this we classify the covalent bonds into two categories of nonpolar covalent and polar covalent which basically differs in electronegativity between bonded atoms.
In a nonpolar covalent bond
electrons are shared equally and there is no sharp dividing line between polar and nonpolar covalent and as per thumb rule the Non polar covalent
would be considered for if the electronegativity difference between bonding atoms is less than 0.5 and hence anything greater than this value will be considered for anything but nonpolar bond
For example the difference of electronegativity between hydrogen and Chlorine in the bond of H-Cl is found to be 3.0 – 2.1 = 0.9 and hence it is considered as polar covalent bond. While the bonding between carbon and hydrogen, the electronegativity difference is 2.5 – 2.1 = 0.4 which classifies this as nonpolar covalent bond. The increasing difference in electronegativity is directly related to increasing bond polarity.
In a nonpolar covalent bond
the shared electrons are not drawn substantially closer to either of the two atoms and as per the rule the chemists have coded it as electronegativity difference in the range of 0 to 0.5 results in nonpolar covalent bond. Any molecule with same bonded atoms would definitely qualify for such covalent bonds. For example the bromine molecule has the same electronegativity difference between the atoms is zero.
This could work out as the shared electrons is not pulled to either end of the molecule which resulted in a nonpolar bond
. The description of delta positive and delta negative notation is not required for this molecule as the electrons are uniformly distributed. Non polar covalent bonds
are typically bonding pattern where the atoms remain electrically neutral as each shared electron stay away from each other where each of are either of same atoms or having same electronegativity value.
Nonpolar covalent examples
for molecules life hydrogen or fluorine diatomic forms where there is aequal sharing of electron pairs. Both the hydrogen atoms in hydrogen molecule as well as the fluorine atoms in fluorine molecule displays equal sharing of bonding electrons and hence is considered as nonpolar covalent bond.
The bonds in hydrogen molecule, fluorine molecule, nitrogen tri chloride (both nitrogen and chlorine have equal abilities to attract electrons) and are considered as nonpolar.
| Non polar covalent molecule
|| Molecule Formula
| Nitrogen tri chloride
There are two types of covalent bonds and the type of bond in a molecule is determined by an atoms ability to share its electrons. A nonpolar covalent bond is formed when atoms share their electrons equally due to the identical atoms presence and as neither atoms could dominate in controlling the shared electrons. The electrons being equally shared makes the molecule as nonpolar in character.
In case we are looking at polar molecules, the bonded atoms become partially positive as one of the bonded atoms loses controls of the electrons. In case of nonpolar bonds none of the bonded atoms never lose control of their electrons and hence never obtain partial positive charge or partial negative charge.
The measure of power to attract electrons that one atom shares in covalent bonding is known as its electronegativity
and atoms with higher atomic number and less atomic radius have higher electronegativity. Higher the electronegativity of an atom, stronger the attraction for oppositely charged atom and hence it’s the electronegativity which helps in formation of polar covalent bond between two atoms and also determines the strength of the bond.
As nonpolar covalent bonds results in atoms sharing electrons equally which results in neither positive nor negative charge. The bonds between two identical atoms result in nonpolar covalent bonds and hence nonpolar covalent bond has the weakest strength as far bond strength is concerned.As compared to nonpolar covalent bond, the covalent bond has higher strength and even more than that the ionic bond has higher strength.The series of strength comparison is as follows:
Ionic bond > covalent bond > hydrogen bonding > dipole – dipole bond > van der Waal forces.