Caffeine is a stimulant that acts upon the central nervous system (CNS) so that cells respond better to signals. This molecule is the most common CNS stimulant. The substance is used for its refreshing effect against fatigue. It is an organic molecule

Caffeine belongs to a group of substances called alkaloids. Alkaloids are found naturally in several plant species, such as coffee, tea, and cocoa.

A 10 membered ring of atoms is made of a 6 membered ring that shares 2 carbons with a 5 membered ring. The atoms in the 10 membered ring are carbon 1, carbon 2, nitrogen 3, carbon 4, nitrogen 5, carbon 6, nitrogen 7, carbon 8, nitrogen 9. The atoms shared between the 6 and 5 membered rings are carbon 2 and 6. A methyl group is attached to nitrogen 3, 7, and 9. A double-bonded oxygen is attached to carbon 1 and 8. A double bond is between carbon 2 and 6, and between carbon 4 and nitrogen 5.

Figure 1: Molecular structure of caffeine