Draw a Lewis structure for each compound. Include all nonbonding pairs of electrons

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Draw a Lewis structure for each compound. Include all nonbonding pairs of electrons.

(a) CH3COCH2CHCHCOOH

(b) NCCH2COCH2CHO

(c) CH2CHCH(OH)CH2CO2H

(d) CH2CHC(CH3)CHCOOCH3

The correct answer and explanation is:

Let’s start by drawing the Lewis structures for each compound. We will also identify and include all nonbonding pairs of electrons (lone pairs) in the drawings. Here’s the step-by-step approach for each molecule.

(a) CH₃COCH₂CH=CHCOOH (Methyl vinyl ketone)

  1. Count the atoms and arrange them:
    • The compound has a total of 10 carbon (C) atoms, 12 hydrogen (H) atoms, and 2 oxygen (O) atoms.
    • The structure contains a ketone group (C=O), a carboxylic acid group (COOH), a double bond between carbons (C=C), and single bonds between the other atoms.
  2. Constructing the skeleton:
    • Start with the central C-C backbone: CH₃-C-O-CH₂-CH=CH-COOH.
    • The first part (CH₃-C=O) is an acetyl group.
    • The second part (CH₂-CH=CH) is the vinyl group.
    • Finally, add the carboxyl group (-COOH).
  3. Assigning bonds and lone pairs:
    • The O in the carboxyl group (COOH) has two lone pairs. The C=O bond in the ketone has no lone pairs on the O.
    • Each C-H bond has two electrons in the form of shared pairs, and each C=C bond has four electrons.
    • The remaining lone pairs are on the oxygen atoms.

(b) NCCH₂COCH₂CHO (2-Cyanopropionyl aldehyde)

  1. Count the atoms and arrange them:
    • This compound contains 7 carbon (C), 9 hydrogen (H), 2 oxygen (O), and 1 nitrogen (N) atom.
    • The structure involves a nitrile group (-C≡N), an aldehyde group (-CHO), and a carbonyl group (-C=O).
  2. Constructing the skeleton:
    • Start with the chain: N≡C-CH₂-C=O-CH₂-CHO.
    • Place the nitrile group at the beginning, then a -CH₂ group, followed by a carbonyl group, and another -CH₂ group, finishing with an aldehyde group.
  3. Assigning bonds and lone pairs:
    • The nitrile group has a triple bond between C and N with one lone pair on the N.
    • The aldehyde and carbonyl oxygens have lone pairs, as typical for carbonyl groups.
    • Hydrogens are attached to C atoms, completing each C’s valence.

(c) CH₂=CH-CH(OH)-CH₂CO₂H (3-Hydroxybutenoic acid)

  1. Count the atoms and arrange them:
    • This compound has 6 carbon (C), 8 hydrogen (H), 3 oxygen (O) atoms.
    • It contains a hydroxyl group (-OH), a carboxyl group (-COOH), and a double bond (C=C).
  2. Constructing the skeleton:
    • The backbone is CH₂=CH-CH(OH)-CH₂CO₂H.
    • Place the hydroxyl group (-OH) on the third carbon, and the carboxyl group (-COOH) on the last carbon.
  3. Assigning bonds and lone pairs:
    • The carboxyl group has lone pairs on the oxygen atoms.
    • The hydroxyl group also has lone pairs on the oxygen.
    • The C=C double bond and single C-H bonds fill the other valence.

(d) CH₂=CH-C(CH₃)-CHCOOCH₃ (Methyl acrylate)

  1. Count the atoms and arrange them:
    • This compound contains 8 carbon (C), 12 hydrogen (H), 2 oxygen (O) atoms.
    • The structure includes an alkene (C=C), a methyl group (-C(CH₃)), and an ester group (-COOCH₃).
  2. Constructing the skeleton:
    • The backbone is CH₂=CH-C(CH₃)-CHCOOCH₃.
    • Attach the methyl group to the central carbon, the ester group (-COOCH₃) to the terminal carbon, and the C=C bond in the middle.
  3. Assigning bonds and lone pairs:
    • The ester group (-COOCH₃) contains lone pairs on the oxygen atoms.
    • The other carbons form bonds as needed to satisfy valency.

Summary of the Lewis Structures

  • (a) Involves an acetyl group (CH₃-C=O), a vinyl group (CH₂=CH), and a carboxyl group (-COOH), with lone pairs on oxygen atoms.
  • (b) Contains a nitrile group (C≡N), aldehyde group (-CHO), and a carbonyl group (C=O) with lone pairs on oxygen atoms.
  • (c) Includes a hydroxyl group (-OH), a carboxyl group (-COOH), and a C=C bond.
  • (d) Features an alkene (C=C), a tertiary carbon (C(CH₃)₂), and an ester group (COOCH₃), with lone pairs on oxygen atoms.

The lone pairs are placed around oxygen atoms in carbonyl and hydroxyl groups, and other nonbonding pairs are assumed to complete the octet for each atom.

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