This work examines two partial oxidation reactions over oxides (alcohols dehydrogenation to aldehydes and aldehydes esterification to esters) to determine how reaction rates can be quantitatively correlated with physical properties of the bulk catalysts. We show that while electronegativity difference, Delta chi, metal-oxygen bond strength, EM-O, fail utterly, oxygen partial charge, q(O), and oxygen Madelung potential, V-Mad (O), do provide limited correlations for the set of roughly twelve oxides examined. However, oxygen electronic polarisability, alpha(O), does a much better job. We rationalise this finding in terms of the concept of chemical hardness in what appears to be the first successful application of this idea to oxide reactivity.