Question

How do electronegativity values determine the charge distribution?

Answer 1

The atom with the greatest electronegativity attracts the electron cloud more strongly gaining the greatest negative charge.

Explanation:

Electronegativity is a measure of the attraction an atom has for electrons.

In `H_2` the two atoms have the same electronegativity so the charge is evenly distributed between the two atoms.

In `H_2O` The Oxygen has an electronegativity of 3.5 while Hydrogen has an electronegativity of only 2.1 There is a difference of 1.4 electronegativity. This is not enough difference to create an ionic bond. However there is enough difference to create a strongly polar bond.

The Oxygen gets the majority of the electron cloud resulting in a partial negative charge on the Oxygen atom. The Hydrogen atom which has less than half of the electron cloud resulting in a partial positive charge

A difference in electronegativity creates a difference in charge distribution.