I would like to know why the ionic substance aluminium oxide doesn't dissolve in water.
Aluminium gives away 3 electrons, and two aluminium atoms are combined with 3 oxygen atoms, the charge is just to great for it to gracefully dissolve.
It does dissolve, but only slightly. It has a solubility of about 0.0001 under atmospheric pressure, it doesn't dissolve because the aluminium is extremely strongly bonded to oxygen, so it can't dissociate very much at all. If you want to dissolve aluminium oxide, you should use an alkaline solution.
