Electronegativity & bond polarity

Electronegativity

The power of an atom to attract electrons in a covalent bonds

Factors effecting electronegativity:

Nuclear charge, Atomic radius , Shielding

Electronegativity decreases

Atomic radius increases, more shielding ,less nuclear attraction between the nucleus and bonded pairs of electrons, These 2 factors have more influence than increasing nuclear charge.

Electronegativity increases

Atomic radius decreases ,More nuclear charge, Stronger nuclear attraction between nucleus and bonded pairs of electrons.These 2 factors have more influence than shielding

Differences in electronegativity between bonded atoms can cause polar bonds:

1. a covalent bond between atoms with different electronegativities, the bonding electrons are more strongly attracted to the more electronegative atom. This unequal sharing of electrons makes the bond polar.

2. Polar bonds have a permanent electric dipole. A dipole is a separation of positive and negative charges within a polar covalent bond or polar molecule, resulting from an uneven distribution of electrons.

3. In a polar bond, the more electronegative atom acquires a slight negative charge (δ^-) and the less electronegative atom acquires a slight positive charge (δ⁺). The bigger the difference in electronegativity, the more polar the bond.

electronegativity difference increases

bond becomes more polar covalent

electronegativity difference is very large

bond is considered ionic

electronegativity difference is zero

pure (non-polar) covalent bond