What is the chemical formula of aluminium oxide?

The chemical formula of Aluminum oxide- ${\mathrm{Al}}_2{\mathrm{O}}_3$

Application of the rules of writing chemical formulas.

• Step 1: Write down the elements.
• Step 2: Write down their valency/charges beneath.
• Step 3: Interchange their valency and write as subscripts.

Let’s learn the concept with an example:

• The symbol for Aluminum is Al and for oxygen, it is O.
• The valency of Al is 3 and O is 2.
• On doing the criss-cross of the valency and writing them as subscripts, the chemical formula of Aluminum oxide becomes Al₂O₃.