Chitin—a white, amorphous, semitransparent mass that is insoluble in common solvents like water and alcohol—is found in the exoskeletons of insects and other arthropods. It is referred to as a glucosamine polysaccharide with the formula of C30H50O19N4. The basic units of this substance are linked together by certain reactions that make up long chains; hydrogen bonds link the chains together and help make chitin rigid and strong.