the chemical formula of water is h2o & the number in chemical formula shows the number of atoms of each element in a molecule ->  the number in chemical formula of water shows the number of atoms of each element in a water molecule  the number in chemical formula of water shows the number of atoms of each element in a water molecule & water is made of hydrogen and oxygen ->  the number in chemical formula of water shows the number of hydrogen and oxygen in a water molecule  the number in chemical formula of water shows the number of hydrogen and oxygen in a water molecule & the chemical formula of water is h2o -> a molecule of water is made of 2 hydrogen atoms and 1 oxygen atom