These elements are described as being electronegative. In the elements common in living systems, both oxygen and nitrogen are electronegative. They will pull the electrons of small atoms, such as hydrogen, closer to themselves, creating polar covalent bonds. In a polar bond, one atom in the bond monopolizes the shared electrons and carries a slight negative charge. The other atom in the bond has less 'access' to the electrons, and thus has a slight positive charge.
Water is a good example of a molecule with polarization.
Complete the electron dot diagram for the formation of water. Expect polarized bonds to form anywhere that oxygen or nitrogen atoms are covalently bonded to hydrogen atoms. Ionic Bonds Ionic bonds are formed between ions. When an atom has gained or lost electrons, it becomes a charged particle, either a positive ion or a negative ion. There is a electrostatic attraction between oppositely charged particles.