A word equation tells us the identities of the reactants and products.
A chemical equation that uses chemical symbols gives much more than the identities
of the substances involved. It gives information about:
the chemical formulas
gives us the proportional amounts of each substances
In the balancing of chemical equations, we are
only allowed to insert coefficients
to make the number of each type of atoms on both sides of the equation equal.
You are not allowed to change the subscripts
in the chemical formulas of the compounds.