Explain the following:
(a) Electronegativity of elements increases on moving from left to right in the periodic table.
(b) Ionisation enthalpy decrease in a group from top to bottom?
Explain the following:
(a) Electronegativity of elements increases on moving from left to right in the periodic table.
(b) Ionisation enthalpy decrease in a group from top to bottom?

(a) The size of the atoms reduces as we move from left to right in a period due to an increase in the effective nuclear charges on the outermost electron. As a result, as you move from left to right in the periodic table, the electronegativity of elements increases.

(b) As we move down the group, atomic size increases, resulting in an increase in the distance between electrons in the outermost shell. Due to this, effective nuclear charge decreases. Hence, the ionization enthalpy decreases.