A water molecule contains an oxygen atom and two hydrogen atoms which are covalently bonded to the oxygen atom.Atoms in a covalently bonded molecule are always fighting for the shared electrons, the atoms attraction to the shared electrons is called the electronegativity. Therefore, the more electronegative an atom is the more it attracts the shared electrons.The force of attraction between a partially electronegative atom and another partially positive atom is the hydrogen bond. It is the hydrogen bond that pulls water molecules together which results into a cohesive force between the water molecules.