Discuss the periodic trend of electronegativity... - SS2 Chemistry Atomic Structure and Periodicity Question

Electronegativity is the measure of an atom's ability to attract shared electrons in a chemical bond.

Across a period in the periodic table, electronegativity generally increases from left to right. This is due to the increasing effective nuclear charge and decreasing atomic radius, which result in a stronger attraction for shared electrons in a chemical bond.

Down a group, electronegativity generally decreases. This is because the atomic radius increases, leading to a decreased attraction for shared electrons. Additionally, the shielding effect from inner electron shells reduces the effective nuclear charge, further weakening the attractive force.

The observed variations in electronegativity are primarily influenced by the balance between the attractive force of the protons in the nucleus and the repulsive force between electrons. As you move across a period, the increasing effective nuclear charge enhances the attraction for shared electrons, resulting in higher electronegativity. Down a group, the increasing atomic radius and shielding effect weaken the attractive force, leading to lower electronegativity.

Electronegativity plays a vital role in determining the nature of chemical bonding and the polarity of molecules. Elements with higher electronegativity tend to attract electrons more strongly and form polar covalent or ionic bonds, while elements with lower electronegativity are more likely to form nonpolar covalent bonds.