Interaction Forces

Molecules, whether biological or synthetic, attract or repel each other, in other words, interact with each other. All kinds of interaction observed in the biological world are based on electrostatics. The essence is, charges of the same signs repel and opposite charges attract each other. In practice, such interactions are classified according to the distribution of electrons within the atoms or molecules in focus. Ions are fully charged, negatively or positively, but uncharged neutral molecules can be either polar or nonpolar depending on the relative positions of negative and positive charge distributions. Polar molecules have a dipole moment. Hydrogen bonds are important in biology because it is a relatively strong interaction between two electronegative atoms having a hydrogen atom in between. Electronegativity is a measure of the tendency of each nucleus in a molecule to attract valence electrons to its side. Other forms of noncovalent interactions are introduced under different conventional names.