Electronegativity is the ability of an atom to attract the shared electron pair towards itself in a covalent bond.
The electronegativity increases from left to right in a period.
The electronegativity decreases down the group.
The key factors that influence electronegativity are as follow:
1. Atomic size
2. Nuclear charge
3. Shielding effect
5. Multiplicity of a bond
Atomic size :
The larger the atomic size of the element in the periodic table refers to the bigger the atomic size.
The bigger atomic size is due to the increase in shell number, the electrons being far away from the nucleus will experience a lesser nuclear force of attraction.
Therefore, it will result in lesser electronegativity values.
Nuclear charge :
Effective nuclear charge (Z) is due to the number of protons in the nucleus of an atom.
The greater nuclear charge will result in a greater electronegativity value.
This happens because the nucleus attracts the electrons more towards itself.
Shielding effect :
The shielding effect is responsible for the decrease in the nuclear force of attraction for the valence shell electrons.
A greater shielding effect will result in a lesser electronegativity value.
Greater the s-character of the hybrid orbital, the greater the electronegativity value.
In sp3 hybridization, we have 25% s-character
In sp2 hybridization ,we have 33.3% s-character
In sp hybridization, we have 50% s-character
so the increasing order of electronegativity values:
sp3 < sp2 < sp
Multiplicity of a bond :
In the case of single, double and triple covalent bonds, the electronegativity value of :
single bond < double bond < triple bond
so with the increase in bond number, the bond length decrease which will result in a greater electronegativity value.
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