Organic molecules mean that chemical compounds contain carbon in them. It is true. Organic also refers to living organisms. So originally, the term organic molecules are found in living things. Carbon can also bond with other four atoms because of its outer shell that has four electrons. This is the reason why organic molecules can be so large because of this bonding. For example, we need proteins in our body in order to perform the necessary functions to live. Proteins are made up of nucleic acids. And nucleic acids have a carbon-nitrogen-hydrogen bond in it.