Draw an 18-carbon saturated fatty acid. Is this a “straight-chain” molecule or a “bent” molecule?

Verified step by step guidance

1. Identify the structure of a saturated fatty acid, which consists of a long hydrocarbon chain with a carboxylic acid group at one end.
2. Recognize that a saturated fatty acid has no double bonds between carbon atoms, meaning all carbon-carbon bonds are single bonds.
3. Draw a chain of 18 carbon atoms in a linear sequence, each bonded to two hydrogen atoms, except for the terminal carbons which are bonded to three hydrogen atoms.
4. Add a carboxylic acid group ($-COOH$) to one end of the chain, replacing one hydrogen atom on the terminal carbon.
5. Conclude that the molecule is a 'straight-chain' because there are no double bonds or branches causing bends in the structure.

Key Concepts

Saturated Fatty Acids

Saturated fatty acids are types of fats that have no double bonds between the carbon atoms in their hydrocarbon chain. This means that each carbon atom is fully 'saturated' with hydrogen atoms. The absence of double bonds allows these fatty acids to pack closely together, resulting in a straight-chain structure, which is typically solid at room temperature.

Molecular Structure

The molecular structure of a fatty acid refers to the arrangement of its carbon and hydrogen atoms. In an 18-carbon saturated fatty acid, the carbon atoms are connected in a linear fashion, forming a straight chain. This structural configuration is crucial for determining the physical properties of the fatty acid, such as its melting point and state at room temperature.

Straight-chain vs. Bent Molecules

Straight-chain molecules have a linear arrangement of atoms, allowing for tight packing and stability, while bent molecules have one or more double bonds that introduce kinks in the chain. In the case of an 18-carbon saturated fatty acid, the absence of double bonds results in a straight-chain configuration, distinguishing it from unsaturated fatty acids, which are bent due to their double bonds.