Carbon dioxide

Carbon dioxide is a compound that usually exists as a gas. One molecule is made up of one carbon atom and two oxygen atoms.

Animals burn fuel to produce carbon dioxide. Plants pull it from the air to produce sugar.

Carbon dioxide can be frozen to make dry ice. Dry ice is useful for keeping goods very cold, and it sublimates directly back to gas, creating no mess as it is consumed.

Carbon dioxide is produced by power plants burning fossil fuels and by most automobiles. It can act as a greenhouse gas, trapping heat.