Chemical Formulae

Symbols are used to represent elements; these symbols are referred to as chemical formulae. The chemical formulae help scientists know the compounds or an element irrespective of the language the name has been written. Chemical formulae are written to show the number of atoms and type of the elements that form the molecule of the compound. A number also written at the subscript of the symbol and the number shows the number of atoms of the element in the formula unit of the compound.

Writing the Chemical Formulae of Compounds

Using the exchange of valencies

Write the symbols of the element involved.

Indicate their valencies below the elements.

The valencies are then interchanged and written as subscripts.

Examples

Magnesium Chloride

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Water

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NB: If the valencies of the elements are not the same and can be divided by a common factor, it can be done.

Example:

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If the valencies of the elements are the same, the valencies must not be written in the chemical formula of the compound.

Example;

Magnesium Oxide

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