Every explanation I can find says something like: valence electrons in metals have low ionising energies and non-metals ''want'' to complete their valence shell.
But I can't seem to get my head around the ''wants to complete it's valence shell'' force.
Take a neutral sodium atom and a neutral chlorine atom separated by some distance. Now move them closer until the valence electron of sodium makes the jump. What force did it feel if chlorine is neutral ? My only explanation is that the valence electron induces a dipole on the chlorine atom. In other words the presence of the valence electron pushes the electron valence orbital of chlorine away slightly. The positive nucleus of the chlorine atom is not pushed away due to shielding by the other shells in chlorine. Now that the valence shell of chlorine is pushed away slightly the valence electron of sodium begins to feel a slight attraction to the chlorine atom despite it being neutral overall. It is now a dipole. At some point the force of attraction between the valence electron of sodium and the chlorine atom is stronger than to the sodium atom and makes the jump.
Is this a reasonable explanation as to why the electron makes the jump or is it something else entirely ?