What determines the ionic nature of a bond? I am a bit confused regarding this. Is it the polarising ability of the cation or the greater electronegativity of the anion? Regarding fajan's rules, smaller the size of the cation (and greater the charge) and smaller the size of the anion, greater is the covalent nature of the bond. So in this case, the bonding pair of electrons is pulled closer to the core of the cation, resulting in accumulation of a slight negative charge for the cation? right? But in some other cases, the shared pair(s) of electrons are pulled closer to the anion due to the greater electronegativity of the anion. So.. does this mean that the bonding pair of electrons can be pulled closer to either to the cation or the anion?? Can someone please explain?