Glucose models. Molecular models of the aldehyde form of glucose (C6H12O6). At top, the molecule is laid out flat. At bottom, the atoms have been linked by bonds to show the bent structure of the molecule. Glucose is a hexose sugar, meaning that it has six carbon atoms. Aldehyde has all six carbon atoms (black) linked in a chain. Hydrogen atoms (white) and hydroxyl groups (OH) are attached to each carbon atom. Oxygen atoms are red. The aldehyde form of glucose exists only in solution. Glucose is found in many plants and is a normal constituent of blood. It is widely used in the confectionary industry as a sweetener.