How do you know that glucose is a compound?

Glucose is a compound because it consists of two or more different elements chemically combined in fixed proportions by mass. In the case of glucose, the elements are carbon, hydrogen, and oxygen. The chemical formula for glucose is C6H12O6, which indicates that each molecule of glucose contains six atoms of carbon, twelve atoms of hydrogen, and six atoms of oxygen. The atoms are arranged in a specific structure, which gives glucose its unique properties.