Why does a more electronegative atom develop a partial negative charge in a covalent bond?

In a covalent bond, atoms share a pair of electrons. Electronegativity is defined as the power of an atom to attract these shared electrons toward itself.12

When two atoms with different electronegativities form a bond, the shared electron pair is not distributed equally. The more electronegative atom exerts a stronger pull on the shared electrons, drawing them closer to its own nucleus. Because electrons carry a negative charge, this shift in electron density causes the more electronegative atom to acquire a partial negative charge. Conversely, the atom that has lost its equal share of the electron pair experiences a reduction in negative charge density, leaving its positive nuclear charge less effectively canceled and resulting in a partial positive charge.2

This unequal distribution of charge creates a polar bond, which can be represented as an electric dipole.2