therefore, these long carboxylate molecules (conjugate bases of carboxylic acids) arrange
themselves into spherical structures known as micelles, in which the charged “heads” (the –COO–
groups) are exposed to the water while the organic chains are inside the sphere. Nonpolar
molecules such as grease can dissolve in the hydrocarbon interior of the spherical micelle. This is
why these molecules, which are salts of long-chain carboxylic acids, are called soaps.
CARBOHYDRATES
Carbohydrates are so named because they are “hydrates of carbon”: They have the general formula
Cn(H 2 O)m, where n is not necessarily the same as m. They serve as chemical sources of energy for
most organisms.
Simple sugars or monosaccharides are carbohydrates and can be classified according to the number
of carbons they possess, and have the general formula Cn(H 2 O)n or CnH 2 nOn. Trioses, tetroses,
pentoses, and hexoses have three, four, five, and six carbon atoms, respectively. Glucose and
fructose are the two most common examples of hexoses:
As you can see, then, these compounds also contain the carbonyl group. In particular, glucose has
an aldehyde functionality while fructose contains a ketone functionality. In solution, however, the
straight-chain forms of these sugars (structures shown above) exist in equilibrium with a cyclic form.