Carbon dioxide molecule. Computer model of a molecule of carbon dioxide. Atoms are colour- coded: carbon (yellow) and oxygen (red). The wireframe surface around the atoms shows electrostatic potential, the ability of the different regions of the molecule to attract electrons, from red (highest attraction) through yellow and light blue to dark blue (least attraction). Carbon dioxide is a colourless gas at room temperature. It occurs naturally in the atmosphere and has an important role in animal and plant respiration.