1. Simple sugars
They are crystalline, soluble in water and sweet substances. They are grouped into monosaccharides like glucose, fructose and disaccharides like maltose, sucrose etc.
Monosaccharides have six carbon atoms per molecule.
E.g. C6H12O6 (glucose). It turns brick red with Fehling’s solution. Monosaccharides are formed by hydrolysis of starch with dilute acid.
(C6H10H5)n → nC6H12O6
Disaccharides – They contain twelve carbon atoms per molecule. It is formed by the condensation of two molecules of monosaccharides by the elimination of one molecule of water.
C6H12O6 + C6H12O6 → C12H22O11 + H2O(L)
(2) Complex Sugars
These are the polysaccharides of long chains of monosaccharides linked together by condensation. Examples are starch and cellulose.