The formula H₂O shows that water is made from two atoms of hydrogen (H) bonded to one atom of oxygen (O). Katie: Time for some science. And today it's a chemistry classic, the periodic table.

the formula for carbon dioxide is CO 2. It has one carbon atom (relative atomic mass = 12.0) and two oxygen atoms (relative atomic mass = 16.0): M r of CO 2 = 12.0 + 16.0 + 16.0 = 44.0 It could ...