Carbon Dioxide is not an element.
More Info: Carbon Dioxide (CO2) is actually a compound. Compounds are made up of individual elements. Because of this, they are inherently not compounds. Carbon Dioxide is made up of two separate elements. There are two atoms of oxygen (hence the oxide) and a single element of carbon.
Major Difference between Elements and Compounds
Elements are different materials located on the periodic table. These include many families of different elements (meaning they all react similarly). These elements represent the smallest unit of distinguishable matter known to man.
Compounds are combinations of different elements. As mentioned above, carbon dioxide is made of two separate elements (carbon and oxygen). Bonds hold these elements together making it difficult to separate them. Another familiar compound is dihydrogen monoxide–also known as water or H20. The compound H2O consists of one oxygen atom and two hydrogen atoms.
Carbon Dioxide in Nature
Although it isn’t an element, CO2 is extremely abundant in nature. Carbon dioxide is made readily through a number of different processes. Combustion is one such process. Combustion is the interaction between two elements to create an explosive reaction. When chemists analyzed the end-results of combustion, they discovered that CO2 was one of the two compounds that consistently popped up at the end of the process. CO2 is also generated through organic chemical reactions. A great example is through breathing. When you inhale, you take in oxygen to be used in the numerous chemical reactions happening every second in your body. Every time you exhale, you are expelling carbon dioxide from your lungs. It’s considered a waste product. Plants then take this waste and revert it back to oxygen.
New York University-Mathematics and Molecules
Elements, Atoms, and Molecules
Combustion of Fossil Fuels
Union of Concerned Scientists
How Much CO2 Is in the Atmosphere and Can That Level Have Dramatic Effects?
The Oxygen Cycle
Carbon Dioxide Information Analysis Center
How Much Carbon Dioxide Is Exhaled with Each Breath?