The molecular formula of n-decane is CH3(CH2)8CH3. Decane is not considered a polymer, whereas polyethylene is. What is the distinction?

A molecular formula represents the number and types of atoms in a molecule. For n-decane, CH3(CH2)8CH3 indicates it consists of 10 carbon atoms and 22 hydrogen atoms. This formula provides insight into the molecule's structure and composition, which is essential for understanding its properties and behavior.

Polymers are large molecules made up of repeating structural units called monomers, linked together by covalent bonds. Polyethylene, for example, is a polymer formed from the polymerization of ethylene monomers. In contrast, n-decane is a simple hydrocarbon with a fixed number of atoms and does not consist of repeating units, thus classifying it as a non-polymeric substance.

The primary distinction between polymers and small molecules lies in their size and structure. Polymers are typically long chains of repeating units, which give them unique physical properties, such as elasticity and strength. Small molecules, like n-decane, are discrete entities with specific molecular formulas and do not exhibit the same extensive chain-like structure, leading to different chemical and physical characteristics.