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Ch. 3 - Alkanes and Cycloalkanes: Properties and Conformational Analysis
Mullins - Organic Chemistry: A Learner Centered Approach 1st Edition
Mullins1st EditionOrganic Chemistry: A Learner Centered ApproachISBN: 9780137566471Not the one you use?Change textbook
All textbooksMullins 1st EditionCh. 3 - Alkanes and Cycloalkanes: Properties and Conformational AnalysisProblem 44a
Chapter 2, Problem 44a

Based on the formal charge, determine how many lone pairs are on each indicated atom.
(a) Diagram showing a molecule with labeled atoms (a) OH group and (b) O atom, indicating formal charge and lone pairs.

Verified step by step guidance
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Step 1: Recall the formula for calculating formal charge: Formal Charge = (Valence Electrons) - (Non-bonding Electrons) - (1/2 × Bonding Electrons). This formula will help us determine the number of lone pairs on the indicated atom.
Step 2: Identify the valence electrons for the indicated atom. Refer to the periodic table to determine the number of valence electrons for the atom in question.
Step 3: Count the bonding electrons around the indicated atom. These are the electrons shared in covalent bonds. Each bond contributes two electrons.
Step 4: Count the non-bonding electrons (lone pairs) around the indicated atom. These are the electrons not involved in bonding. Use the formal charge formula to solve for the number of non-bonding electrons.
Step 5: Divide the non-bonding electrons by two to determine the number of lone pairs on the indicated atom. Verify your result by ensuring the formal charge matches the given or expected value.

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Key Concepts

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

Formal Charge

Formal charge is a theoretical charge assigned to an atom in a molecule, calculated by taking the number of valence electrons in the free atom, subtracting the number of non-bonding electrons, and half the number of bonding electrons. It helps in determining the most stable structure of a molecule by minimizing the formal charges across the atoms.
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Calculating formal and net charge.

Lone Pairs

Lone pairs are pairs of valence electrons that are not involved in bonding and are localized on a specific atom. They play a crucial role in determining the geometry and reactivity of molecules, as they can influence the shape and polarity of the molecule.
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Lewis Structures

Lewis structures are diagrams that represent the bonding between atoms in a molecule and the lone pairs of electrons that may exist. They provide a visual representation of the arrangement of electrons, allowing for the determination of formal charges and the identification of lone pairs on specific atoms.
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Related Practice
Textbook Question

Given the line-angle drawings shown, answer the following questions:

(i) How many carbons are in each molecule?

(ii) How many hydrogens are at the circled carbon?

(iii) Is the indicated (→) carbon or 1° , 2°, 3°, or 4°?

(c)

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Textbook Question

Draw the most stable chair conformation for the following trisubstituted cyclohexane.

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Textbook Question

Draw two different chair conformations for each of the following molecules. Make sure that your drawings clearly show the cis–trans stereochemistry.

(c)

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Textbook Question

Modify the following line-angle drawings to show all lone pairs.

(b)

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Textbook Question

Modify the following line-angle drawings to show all lone pairs.

(a)

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Textbook Question

For each pair of conformations you drew in Assessment 3.41, indicate which is most stable.

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