Question

How does electronegativity affect covalent bonding?

Answer 1

Electronegativity differences affect the degree of sharing in covalent bonding. The more equal the sharing the stronger the bond.

Explanation:

Electronegativity differences affect the degree of sharing in covalent bonding. The more equal the sharing the stronger the bond.

If the electronegativities of the two atoms are completely the same, the bond formed by the sharing of the electrons will be a pure covalent bond.

An example would be `H_2, H:H`. The pair of electrons (one from each atom) that forms the bond is shared equally between the two hydrogens because the difference in electronegativity is zero.

If the electronegativities of the two atoms are close to the same, it is still a covalent bond even though the sharing is not exactly equal.

An example would be a hydrocarbon like methane `CH_4`

      H          
      ..
 H: C : H    Hydrogen has an electronegativity of 2.2.
      ..          Carbon has an electronegativity of 2.5. 
      H         The difference of 0.3 is very small.

If the difference in electronegativity is significant, the bond created is a polar covalent bond, such as that formed in water, `H_2O`.

`H:O color(white)(m)`The Oxygen has an electronegativity of 3.5.
`color(white)(mll)..color(white)(ll)`This creates a difference of 1.3, so that the electrons are
`color(white)(mll)Hcolor(white)(m)`pulled strongly toward the oxygen.

This allows the hydrogen to form intermolecular bonds called hydrogen bonds with other molecules. It also allows the hydrogen to be more easily pulled away from the oxygen, completely breaking the chemical bond.