Although the above equation does correctly show that
hydrogen and oxygen combine to form water, it is not
entirely correct because the number of atoms on each side of
the arrow is not equal. The equation is more properly
written as...
2H2 + O2 ->
2H2O
The equation now shows that two hydrogen molecules combine
with one oxygen molecule to form two water molecules. Note
that there are four hydrogen atoms and two oxygen atoms on
each side of the equation.
