2Al(s) + 3H2O(g) -------- Al2O3(s) + 3H2(g)
why in the above reaction metal oxide is formed? why not metal hydroxide?
Dear student!
Normally, the alkaline earth metals form hydroxides with water but, the aluminium first forms a thin layer of oxide when react with water. This aluminium oxide Al2O3 is very hard substance which does not dissolve in water easily. So, it could not be able to further dissolve it to form the hydroxide, while the other metals can dissolve their oxides.
This, behavior is shown because of rapid reaction of aluminum with water.