Electronegativity is the power of a covalently bonded atom to attract the shared pair of electrons towards itself.
Explanation level
This topic explains electronegativity — what it is, what factors affect it, and how it varies across the periodic table. It also explains how electronegativity differences determine the nature of chemical bonds.
Definition
Electronegativity is the power of a covalently bonded atom to attract the shared pair of electrons towards itself.
Factors Affecting Electronegativity
Size of atom: Smaller atom → higher electronegativity.
It is the power of a covalently bonded atom to attract the shared pair of electrons towards itself in a molecule.
It is a dimensionless property and has no unit because it is only a tendency.
It indicates the net result of the tendencies of atoms in different elements to attract the bond-forming electron pairs.
We measure electronegativity on several scales. The most commonly used scale was designed by Linus Pauling.
Factors Affecting Electronegativity
Electronegativity depends upon the following factors:
Size of atom
Nuclear charge
Screening by inner electrons
As the number of protons in the nucleus increases, the nuclear charge increases.
Hence the size of atom decreases, causing the attraction of bonded electrons with the nucleus to increase, resulting in an increase of electronegativity.
When the number of inner shell electrons increases, the distance between the nucleus and valence electrons increases.
So, the attraction of bonded electrons with the nucleus decreases, causing a decrease in electronegativity.
Important Points
1. Electronegativity = power of an atom to attract shared electrons.
2. It is a dimensionless property (no units).
3. Pauling scale is the most commonly used.
4. Factors: Size, nuclear charge, screening by inner electrons.
- Covalent character: Increases with polarising power
Common Mistakes
1. Thinking electronegativity has units: It is dimensionless.
2. Confusing electronegativity with electron affinity: Electronegativity is about attracting shared electrons; electron affinity is about gaining an electron.
3. Forgetting the shielding effect: It decreases electronegativity down a group.
4. Mixing up the bond type ranges: Ionic > 1.8; Polar covalent 0.4–1.8; Nonpolar covalent ≤ 0.4.
Quick Revision
Electronegativity = power of an atom to attract shared electrons.
It is a dimensionless property (no units).
Pauling scale is the most commonly used.
Factors: Size, nuclear charge, screening by inner electrons.
