Cigarettes and smokeless tobacco both contain the active ingredient nicotine, which is an organic compound with psychoactive properties, meaning that it acts upon the brain. Nicotine produces a feeling of arousal, meaning that it increases alertness and attention. It also suppresses appetite. The nicotine molecule is made up of three separate elements, which work together to produce its chemical properties.
Nitrogen
Of the elements in nicotine, the one most directly responsible for its activity in the brain is nitrogen. The element nitrogen is the heaviest of the three elements in nicotine, but it is still relatively light in weight compared to many other elements. There are two atoms of nitrogen in nicotine, both of which are incorporated into the molecule's general shape, or backbone, which according to the "CRC Handbook of Chemistry and Physics," consists of two ring structures. Many of the molecules---including street drugs, pharmaceuticals and brain chemicals---that bind to receptors in the brain and activate brain responses are nitrogen-containing. Both the shape of the nicotine molecule and its nitrogen atoms contribute to its psychoactive nature.
Carbon
Nicotine also contains atoms of the element carbon, which is perhaps the most important of the organic elements. Life on Earth is carbon-based, meaning that organic molecules, or those that make up living organisms, have carbon-dominated structures. The backbone of any organic molecule is made up of carbon. Nicotine, with 10 atoms of carbon, is no exception. The backbone of nicotine consists of a six-membered ring, five members of which are carbon, and a five-membered ring, four members of which are carbon. Drs. Reginald Garrett and Charles Grisham note in their text "Biochemistry" that carbon atoms in a chemical backbone are relatively unreactive, but they do determine the overall shape of a molecule, which is important to the molecule's ability to bind to receptors in the body.
Hydrogen
The most numerous and lightest of the elements in nicotine is hydrogen, of which there are 14 atoms. Hydrogen atoms have the ability to make only one chemical bond, meaning they can't connect multiple other atoms to one another. Instead, in nicotine, hydrogen atoms are attached to the carbon backbone. Some hydrogen atoms in nature are quite reactive. Drs. Mary Campbell and Shawn Farrell, in their book "Biochemistry," note that generally these reactive hydrogen atoms are bound to elements like nitrogen and oxygen. Hydrogen atoms bound to carbon are typically quite unreactive. Because hydrogen is so small, it doesn't contribute significantly to the overall shape of nicotine. Still, the presence of hydrogen is important to the molecule, because hydrogen atoms complete the bonding requirements of carbon, and make the carbon skeleton more stable.
References
- "CRC Handbook of Chemistry and Physics"; David Lide; 1974
- "Biochemistry"; Reginald Garrett, Ph.D., and Charles Grisham, Ph.D.; 2007
- "Biochemistry"; Mary Campbell, Ph.D., and Shawn Farrell, Ph.D.; 2005
