Life on earth would not exist without the many bonds observed throughout Biochemistry. There is two types of force the intramolecular force which exist between the atoms in a molecule such as Covalent, Ionic and Metallic bonding, the second force being intermolecular force that exist between neighboring molecules such a Hydrogen bonding, dispersion forces and dipole-dipole bonds. Hydrogen bonding being a weak chemical bond is one of the most important bonds present in essential biological molecule.
Nearly all molecules have London dispersion forces, Hydrogen Bonds Fig. 1 form between molecules consisting of dispersion forces and Dipole-dipole bond. Hydrogen bond is the forces of attraction between a Nitrogen, Oxygen or Fluorine atom of another molecule and the hydrogen atom attached in the molecule. Nitrogen, Oxygen or Fluorine are heteroatoms suggested by Alan R. Katritzky, Otto Meth-Cohn, Thomas L. Gilchrist – (1995) which means that electronegativity of Nitrogen, Oxygen and Fluorine is great than Hydrogen but also all the other elements in the periodic table explained by William C. Robertson (2007) according to the Pauling scale of electro-negativities of the elements. This means that hydrogen will have a partial positive charge and the heteroatoms have a partial negative charge. .
Water being one of the essential biological molecules is usually used to explain the Chemistry of hydrogen bond formation. Darrell Ebbing, Steven D. Gammon (2010) defines Covalent bonding where two atoms share one or more single pair of electrons, in the case of water there is pair of free electron shared in the covalent bond one from Hydrogen and the other from Oxygen which are attracted to Oxygen being the most electronegative in the molecule therefore oxygen becomes slightly delta-negative leaving hydrogen as slightly delta-positive. As opposite electrostatic charged atoms attract, Hydrogen being slightly delta-positive enables it to attract a lone pair of electron from another slightly delta-negative charged atoms such as the Oxygen from another water molecule forming hydrogen bond.
