The structural formulas for 2,2-diethylbutane and 2,3-dimethylpentane involve drawing the base carbon chains for butane and pentane, respectively, and then attaching the specified alkyl groups at the correct positions.
The structural formula for 2,2-diethylbutane depicts a butane molecule (four-carbon chain) with two ethyl groups (two-carbon chain) attached to the second carbon atom of the butane. To draw it, begin with a four-carbon chain and attach an ethyl group to each side of the second carbon.
The structure of 2,3-dimethylpentane showcases a pentane molecule (five-carbon chain) with one methyl group (one-carbon chain) attached to the second carbon atom and another methyl group attached to the third carbon atom. Start with a five-carbon chain, then attach a methyl group to the second and third carbons.
Remember that each carbon atom makes four bonds, typically filled with hydrogen atoms if not specified otherwise.