An organic compound is any member of a large class of chemical compounds whose molecules contain carbon; for historical reasons discussed below, a few types of compounds such as carbonates, carbon oxides and cyanides, as well as elemental carbon are considered inorganic.The study of organic compounds is termed organic chemistry, and since it is a vast collection of chemicals (over half of all known chemical compounds), systems have been devised to classify organic compounds. A few of the compound classes based on the functional groups they carry are as follows: