The Glucose molecule - rotatable in 3 dimensions

Glucose (also known as dextrose or blood sugar) is a monosaccharide - formula C₆H₁₂O₆.

It is an example of a 6-carbon (hexose) sugar. Label / unlabel Carbon numbers.

Notice the 6 carbon atoms (grey) forming the backbone of the molecule, and the oxygen atom (red) in the ring.

The hydrogen atoms (white) are either attached directly to the carbons, or via oxygen as OH groups - at an angle.

The glucose molecule can form into other configurations, but this structure - a ring or chair form - is the most stable and therefore most common in biological systems.

The ring itself is 6-sided, but only 5 of its corners are made up by carbon atoms.
Only the carbon outside the ring (number 6) has 2 single hydrogens and an OH group.

The glucose molecule in this form is known as α-D-glucopyranose, as the central part of the molecule is similar to pyran - a six-membered heterocyclic ring-shaped compound with five carbon atoms and one oxygen.

It is in equilibrium with a open-chain form in which Carbon 1 forms a CHO aldehyde group which gives it reducing properties, so that it reacts with reagents such as Benedict's.

Glucose is a component of other biological molecules: maltose, lactose, sucrose, cellobiose, amylose, amylopectin, glycogen.
See the carbohydrates section of the 3-D molecules index, above.