The chemical formula for water is H2<span>O which means that every </span>molecule<span> of water has 2 </span>atoms<span> of hydrogen (H) and one </span>atom<span> of oxygen (O). Here comes the key part. From the Periodic Table of Elements, one sees that one mole of hydrogen </span>atoms weighs <span>1 gram while one mole of oxygen </span>atoms<span> weighs 16 grams.</span>
