Nitrogen (N2), oxygen (O2) and Argon (Ar) molecules compromise 99% of Earth’s atmosphere. Though these molecules become excited by heat, they are too small to absorb infrared thermal radiation. The larger molecules of carbon dioxide (CO2), methane (CH4), water vapor (H2O), nitrous oxide (N2O), and various fluorinated gases do, however, absorb the photonic energy known as infrared radiation (IR) and re-emit it. This creates the greenhouse effect.
Carbon dioxide and the Greenhouse Effect (3 minutes)-Lab demonstration at 1 min 33 second point: