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Ch. 1 - Remembering General Chemistry: Electronic Structure and Bonding (Part 2)
Bruice - Organic Chemistry 8th Edition
Bruice8th EditionOrganic ChemistryISBN: 9780135213711Not the one you use?Change textbook
All textbooksBruice 8th EditionCh. 1 - Remembering General Chemistry: Electronic Structure and Bonding (Part 2)Problem 69
Chapter 2, Problem 69

In which orbitals are the lone pairs in nicotine?
Chemical structure of nicotine, highlighting nitrogen atoms and lone pairs in the molecular diagram.

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1
Step 1: Analyze the structure of nicotine. Nicotine contains two nitrogen atoms, each with lone pairs of electrons. One nitrogen is part of a pyridine ring, and the other is part of a pyrrolidine ring.
Step 2: Determine the hybridization of the nitrogen atoms. The nitrogen in the pyridine ring is sp2 hybridized because it is part of an aromatic system, while the nitrogen in the pyrrolidine ring is sp3 hybridized because it is part of a saturated ring system.
Step 3: Consider the orbital location of the lone pairs. For the sp2 hybridized nitrogen in the pyridine ring, the lone pair resides in an sp2 orbital, which is oriented in the plane of the ring. For the sp3 hybridized nitrogen in the pyrrolidine ring, the lone pair resides in an sp3 orbital, which is tetrahedrally oriented.
Step 4: Note the implications of aromaticity. The lone pair on the sp2 hybridized nitrogen does not participate in the aromatic π-system of the pyridine ring because it is localized in the sp2 orbital.
Step 5: Summarize the orbital locations. The lone pair on the pyridine nitrogen is in an sp2 orbital, and the lone pair on the pyrrolidine nitrogen is in an sp3 orbital.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Molecular Orbitals

Molecular orbitals are formed by the combination of atomic orbitals when atoms bond together. In nicotine, the arrangement of these orbitals determines the distribution of electrons, including lone pairs. Understanding how these orbitals overlap helps in visualizing the electron density and the geometry of the molecule.
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Lone Pairs

Lone pairs are pairs of valence electrons that are not involved in bonding and are localized on a single atom. In nicotine, the presence of lone pairs affects the molecule's shape and reactivity. Identifying the location of these lone pairs is crucial for predicting the molecule's behavior in chemical reactions.
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Hybridization

Hybridization is the concept of mixing atomic orbitals to form new hybrid orbitals that can accommodate bonding and lone pairs. In nicotine, understanding the hybridization of the nitrogen atom helps determine the geometry and orientation of the lone pairs. This concept is essential for predicting molecular shape and reactivity.
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Related Practice
Textbook Question

Rank the following compounds from highest dipole moment to lowest dipole moment:

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Textbook Question

Do the sp2 carbons and the indicated sp3 carbons lie in the same plane?

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Textbook Question

a. Which of the species have bond angles of 109.5°?

b. Which of the species have bond angles of 120°?

H2O H3O+ +CH3 BF3

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Textbook Question

For each of the following molecules, indicate the hybridization of each carbon and give the approximate values of all the bond angles:

d. CH2═CH—CH═CH2

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Textbook Question

Draw a Lewis structure for each of the following:

c. (CH3)2CHCH(CH3)CH2C(CH3)3

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Textbook Question

a. Which of the species have bond angles of 109.5°?

b. Which of the species have bond angles of 120°?

NH3 +NH4 -CH3

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