In organic chemistry, a hexose is a monosaccharide with six carbon atoms having the chemical formula C6H12O6. Hexoses are classified by functional group, with aldohexoses having an aldehyde at position 1, and ketohexoses having a ketone at position 2. Aldohexoses The aldohexoses have four chiral centres for a total of 16 possible aldohexose stereoisomers (24). The D/L configuration is based on the orientation of the hydroxyl at position 5, and doesn't refer to the direction of optical activity.… (More on Hexose)