Living organisms are made of organic and inorganic substances. How can each of these substances be classified based on the complexity of their molecules?

Inorganic substances, such as water, mineral salts, molecular oxygen and carbon dioxide, are small molecules made up of few atoms. Organic substances, in general, such as glucose, fatty acids and proteins, are much more complex molecules made of sequences of carbons bound in carbon chains. The capacity of carbon to form chains is one of the main chemical facts that allowed for the emergence of life on the planet.