Q

QuestionChemistry

Electronegativity is a property of an atom that describes its ability to attract a shared pair of electrons (or electron density) towards itself in a covalent bond. The higher the electronegativity, the more an atom attracts the shared electrons.

As you move across a period (left to right) in the periodic table, electronegativity generally increases due to the increasing nuclear charge and smaller atomic radius. However, as you move down a family (from top to bottom), electronegativity decreases.

The decrease in electronegativity down a family is primarily due to two factors: A) Increasing atomic size: As you move down a family, atomic radii increase. This larger size results in a weaker attraction of the nucleus for the outermost electrons. Consequently, the atom's ability to attract shared electrons in a covalent bond decreases, leading to a lower electronegativity value. B) Core electron shielding: The inner electrons in larger atoms create a shielding effect, reducing the effective nuclear charge felt by the outermost electrons. This decreased effective nuclear charge also weakens the attraction of the nucleus for the outermost electrons, further decreasing the atom's ability to attract shared electrons in a covalent bond.

In summary, electronegativity decreases down a family due to the increasing atomic size and the shielding effect of inner electrons, both of which weaken the attraction of the nucleus for the outermost electrons. As a result, the atom's ability to attract shared electrons in a covalent bond decreases, leading to a lower electronegativity value.