Classify these oxides as acidic, basic, amphoteric, or neutral. P4O10, At2O7, Al2O3, SnO2, MgO, Li2O, CO, NO. Begin by classifying the element (other than oxygen) in each oxide by where it appears on the periodic table. In general, oxides of elements further to the left on the periodic table are basic, moving toward acidic on the right. For nonmetallic oxides, when the oxidation number of the element other than oxygen is high, the oxide tends to be acidic. When the oxidation number of this element is low, the oxide is generally neutral