Writing formulae of simple covalent molecules

The chemical formula for a simple covalent molecule shows:

For example, the formula H2O shows that a water molecule contains two hydrogen atoms and one oxygen atom.

Useful formulae of simple covalent molecules:

CompoundFormula
WaterH2O
Carbon dioxideCO2
Carbon monoxideCO
Nitrogen dioxideNO2
Nitrogen monoxideNO
Sulfur dioxideSO2
MethaneCH4