Oxides can be both metallic and non metallic. These oxides can further described as acidic, basic, neutral and amphoteric oxides.

Acidic Oxides (non metallic)

Acidic oxides are oxides of non-metals that neutralize bases to form salt and water only, example:
-Carbon Dioxide
CO_{2 (g)}+ 2 NaOH _(aq) →  Na₂CO_3(s) + H₂O _(l)

Acidic Anhydride

An acidic anhydride is an acidic oxide which dissolves in water to form an acid solution.

CO_{2 (g) +} H₂O_(l)→ H₂CO3_(aq) carbonic acid

SO_{3 (g)} + H₂O_(l) →  H₂SO4_(aq) sulphuric acid

NO₂ is a mixed acid anhydride because it dissolves in water to produce 2 acids:

2NO_{2 (g)} +   H₂O_(l) →HNO_{3(aq) +} HNO_{2 (aq)} nitric acid

Basic Oxides

These are oxides of metal which neutralize acids to form salt and water only. For example the basic oxide MgO (magnesium oxide) neutralises Sulphuric acid to form magnesium sulphate (salt) and water.

MgO _(s) + H₂SO4 _(aq) →  MgSO_4(aq) + H₂O_(l)

Basic oxides can be either soluble or insoluble. Soluble oxides dissolve in water to form alkaline solutions.

Neutral Oxides

These are oxides of non-metal that neither neutralizes acids or base, example CO, NO and H₂O

Amphoteric Oxides

These are oxides of metals that neutralize both acid and bases to form a salt and water

Examples: Al₂O3, ZnO

ZnO_(s) + H₂SO4 _{(aq) →}ZnSO4_(aq) + H₂O

ZnO + NaOH + H2O →   Na₂ (Zn (OH)₄)

Na₂ (Zn (OH)₄) – This is a complex ion. You will be introduced to this later in your studies in chemistry. For now, appreciate the fact that ZnO is an amphoteric oxide which neutralizes both acidic and alkaline solutions.