WHERE DO ELECTRONS ROTATE WHEN TWO ATOMS SHARE THEIR ELECTRONS
When two atoms share their electrons forming covalent bond then shared electrons rotate between the two atoms i.e. shared electrons are localised on the line joining the two atoms. If two atoms have different electronegativities then the more electronegative atom exerts more force on the shared pair of electron and as a result electrons move slightly towards the more electronegative atom. Thus, more electronegative atom has partial negative and other atom has partial positive charge.