MonosaccharidesBased on the number of carbons, monosaccharides can be called trioses (three carbons), tetroses (four carbons), pentoses (five carbons), hexoses (six carbons), heptoses (seven carbons), octoses (eight carbons), and so on.
Monosaccharides contain many hydroxyl groups and a carbonyl group. If a monosaccharide contains an aldehyde group, it is called an aldose sugar. If a monosaccharide contains an keto group, it is called an ketosesugar.
Figure: Glucose is an aldose sugar. Fructose is a ketose sugar.
Figure: D-aldose sugars