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

Verified step by step guidance

1. Step 1: Understand the structure of a saturated fatty acid. A saturated fatty acid contains only single bonds between carbon atoms, meaning there are no double or triple bonds in the hydrocarbon chain.
2. Step 2: Recognize that the molecule has 18 carbon atoms. The structure will consist of a carboxylic acid group (COOH) at one end and a long hydrocarbon chain of 17 carbon atoms attached to it.
3. Step 3: Draw the carboxylic acid group (COOH) at one end of the molecule. This is the functional group that defines the molecule as a fatty acid.
4. Step 4: Add 17 carbon atoms in a straight chain, each bonded to two hydrogen atoms (except for the terminal carbon, which will have three hydrogens). Use the general formula for a saturated fatty acid: \( C_nH_{2n+1}COOH \), where \( n \) is the number of carbons in the chain.
5. Step 5: Determine the shape of the molecule. Since there are no double bonds, the molecule will be a 'straight-chain' structure, as the single bonds allow the carbon atoms to align in a linear fashion without kinks or bends.

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 solid state at room temperature, which is characteristic of saturated fats.

Molecular Structure

The molecular structure of a fatty acid includes a long hydrocarbon chain with a carboxylic acid group at one end. In the case of an 18-carbon saturated fatty acid, the chain consists of 18 carbon atoms linked by single bonds. This structure is typically linear or 'straight-chain' due to the lack of double bonds, which would otherwise introduce bends or kinks in the chain.

Straight-Chain vs. Bent Molecules

Straight-chain molecules have a linear arrangement of atoms, allowing them to pack tightly together, while bent molecules have one or more double bonds that create angles in the chain. In the case of an 18-carbon saturated fatty acid, the absence of double bonds means it is a straight-chain molecule, which influences its physical properties and behavior in biological systems.