molecular biology. (mÉ-lÄk'yÉ-lÉr) The branch of biology that deals with the formation, structure, and function of macromolecules essential to life, such as nucleic acids and proteins, including their roles in cell replication and the transmission of genetic information.
Molecules containing more than two atoms are termed polyatomic molecules, e.g., carbon dioxide (CO2) and water (H2O). Polymer molecules may contain many thousands of component atoms. A water molecule is made up of two hydrogen atoms and one oxygen atom. A single oxygen atom contains six electrons in its outer shell, which can hold a total of eight electrons. When two hydrogen atoms are bound to an oxygen atom, the outer electron shell of oxygen is filled. EncyclopÃ¦dia Britannica, Inc.
A molecule like CO2 may be composed of two dipoles, but it has no dipole moment. This is because the charge is equally distributed amongst the entire molecule. When molecules have an even charge distribution and no dipole moment then they are nonpolar molecules. CO2 is a linear molecule, so our dipoles are symmetrical; the dipoles are equal in magnitude but point in opposite directions.