Made up of two elements, one element is a compound of oxygen. Could have a material reacts with oxygen are called oxides. According to the different chemical properties, oxides acidic oxides and alkaline oxides can be divided into two broad categories. Acidic oxide: energy and water into salt acid or alkali oxides. Such as sulfur, phosphorus pentoxide oxide, carbon dioxide and other, non-metallic oxides mostly acidic oxides.
Basic oxides: water can react with acids to form salts and oxides, and produce the only salt and water, can not have any other substance. Basic oxides include active metals oxides and other metal oxides of low price, like CaO, BaO and CrO, MnO.