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

Verified step by step guidance

1. Step 1: Define what a polymer is. A polymer is a large molecule composed of repeating structural units, typically connected by covalent chemical bonds. These repeating units are called monomers.
2. Step 2: Identify the structure of polyethylene. Polyethylene is a polymer made from the monomer ethylene (C2H4). During polymerization, the double bonds in ethylene open up and link together to form long chains of repeating -CH2- units.
3. Step 3: Analyze the structure of n-decane. The molecular formula of n-decane is CH3(CH2)8CH3, which indicates a single, linear chain of carbon atoms with hydrogen atoms filling the remaining valences. It does not have repeating monomeric units.
4. Step 4: Compare the structures. Polyethylene consists of long chains of repeating units, whereas n-decane is a single, finite molecule without repeating units. This structural difference is key to why polyethylene is a polymer and n-decane is not.
5. Step 5: Conclude the distinction. The distinction lies in the presence of repeating monomeric units in polymers like polyethylene, which n-decane lacks, making it a simple alkane rather than a polymer.

Key Concepts

Molecular Formula

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

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.

Distinction Between Polymers and Small Molecules

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.