A water molecule is made up of two hydrogen atoms and one oxygen atom. When the two hydrogen atoms get close enough to an oxygen atom their electrons will become attracted to the proton of the oxygen atom. The electrons in the oxygen atom will also be attracted to the protons in the hydrogen atoms. This is a strong attraction between the atoms. As well as this strong attraction, the hydrogen and oxygen atoms have room for electrons in their outer energy levels. This means that they share electrons which forms a covalent bond between the atoms.