Which of the following molecules is an amide?

• A. ${\mathrm{CH}}_3\mathrm{CONH}{2}_{}$
• B. ${\mathrm{CH}}_3\mathrm{COOH}$
• C. ${\mathrm{CH}}_3\mathrm{CH}{2}_{}\mathrm{OH}$
• D. ${\mathrm{CH}}_3\mathrm{CHO}$

Answer: (A)

Verified step by step guidance

1. Step 1: Understand the functional groups involved. An amide functional group consists of a carbonyl group (C=O) directly bonded to a nitrogen atom (N), typically represented as -CONH2, -CONHR, or -CONR2.
2. Step 2: Examine each molecule's structure to identify the functional groups present. For example, look for the presence of a carbonyl group (C=O) and check if it is attached to a nitrogen atom.
3. Step 3: Analyze the first molecule, \(\mathrm{CH_3CONH_2}\), which has a methyl group (\(\mathrm{CH_3}\)) attached to a carbonyl group (\(\mathrm{C=O}\)) bonded to an amine group (\(\mathrm{NH_2}\)). This matches the amide functional group.
4. Step 4: Compare the other molecules: \(\mathrm{CH_3COOH}\) is a carboxylic acid (carbonyl attached to OH), \(\mathrm{CH_3CH_2OH}\) is an alcohol (hydroxyl group), and \(\mathrm{CH_3CHO}\) is an aldehyde (carbonyl attached to hydrogen). None of these have the amide functional group.
5. Step 5: Conclude that the molecule with the structure \(\mathrm{CH_3CONH_2}\) is the amide because it contains the characteristic carbonyl group bonded directly to nitrogen.