Question

Why is electronegativity directly proportional to $s$ character?

Answer 1

Hint :An atom is more stable when the electrons in its outermost orbitals are either all paired or are all unpaired, rest of the configurations are less stable. The character in a particle is the tendency to have the last number of electrons in the and also the percentage of sigma bonds in the compound.

Complete Step By Step Answer:
Electronegativity is the tendency of an atom in a molecule to attract the shared pair of electrons towards itself. Electronegativity increases as you go across a period from left to right as the nuclear charge increases and atomic size decreases. While as we go down the group, the nuclear charge increases but is compensated by the fact that orbitals also increase, therefore, the electronegativity decreases.
Electronegativity also depends on the distance of the nucleus from the outermost orbital, as the closer the greater the tendency to attract another atom’s electron.
Now the $s$ orbital is closer to the nucleus than $p$ orbital, therefore electrons present in the closer one will be able to attract electrons more easily. The larger the charge on the nucleus, higher the tendency to attract electrons and also as close to the last orbital smaller it would be with higher charge and that would make it more electronegative.
Now what happens here is that the $s$ character is when possessed by the element, then its ratio tells us about the $s$ character percentage. The greater the percentage, the greater will be its closeness to the nucleus of the element. The closer it is to the nucleus; with greater power it will be able to attract it and therefore higher the electronegativity.
Electronegativity is directly proportional to $s$ character as it is directly proportional to the closeness to the nucleus of its last orbital.

Note :
The more the electronegative compound from left to right, the acidic nature of the oxides of the elements also increases. While the basic nature of oxides of the elements decreases as we go from left to right.