IS there charge on all colloidal partciles? My book states that charge is the reason why colloidal partciles are stable, otherwise they would coagulate I always thought that it was their size that made them float. I dont understand how they attain charge - they are not like ionic compounds such that they would get charge For example :- metals sols like gold sols are negatively charged , blood is positvely charged I dont get it. Where does this charge come from?? IS it necessary for colloids to have charge?