CFC molecule. Computer model of a molecule of dichlorodifluoromethane, also known as Freon-12. Atoms are represented as spheres and are colour- coded: carbon (grey), chlorine (light green) and fluorine (dark green). This colourless gas is used as a refrigerant. It is a member of the CFC (chlorofluorocarbon) class of compounds, whose use is thought to have contributed to the depletion of the ozone layer.