Table of contents

1. A Review of General Chemistry5h 5m
2. Molecular Representations1h 14m
3. Acids and Bases2h 46m
4. Alkanes and Cycloalkanes4h 17m
5. Chirality3h 39m
6. Thermodynamics and Kinetics1h 22m
7. Substitution Reactions1h 48m
8. Elimination Reactions2h 30m
9. Alkenes and Alkynes2h 9m
10. Addition Reactions3h 19m
11. Radical Reactions1h 58m
12. Alcohols, Ethers, Epoxides and Thiols2h 42m
13. Alcohols and Carbonyl Compounds2h 17m
14. Synthetic Techniques1h 26m
15. Analytical Techniques:IR, NMR, Mass Spect7h 3m
16. Conjugated Systems6h 13m
17. Ultraviolet Spectroscopy51m
18. Aromaticity2h 34m
19. Reactions of Aromatics: EAS and Beyond5h 1m
20. Phenols55m
21. Aldehydes and Ketones: Nucleophilic Addition4h 56m
22. Carboxylic Acid Derivatives: NAS2h 51m
23. The Chemistry of Thioesters, Phophate Ester and Phosphate Anhydrides1h 10m
24. Enolate Chemistry: Reactions at the Alpha-Carbon1h 53m
25. Condensation Chemistry2h 9m
26. Amines1h 43m
27. Heterocycles2h 0m
28. Carbohydrates5h 53m
29. Amino Acids4h 20m
30. Peptides and Proteins2h 42m
31. Catalysis in Organic Reactions1h 30m
32. Lipids 2h 50m
33. The Organic Chemistry of Metabolic Pathways2h 52m
34. Nucleic Acids1h 32m
35. Transition Metals6h 14m
36. Synthetic Polymers1h 49m

1. A Review of General Chemistry

Skeletal Structure

Organic Chemistry

1. A Review of General Chemistry

Skeletal Structure

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5:31 minutes

Problem 46f

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°?
(f)

Verified step by step guidance

Step 1: Analyze the line-angle drawing provided. In line-angle drawings, each vertex represents a carbon atom, and lines represent bonds between atoms. Count the number of vertices to determine the total number of carbon atoms in the molecule.

Step 2: Identify the circled carbon atom in the drawing. Recall that each carbon atom forms four bonds. If the circled carbon is bonded to other carbons or hydrogens, determine the number of hydrogens by subtracting the number of bonds to other atoms from four.

Step 3: Locate the indicated (→) carbon atom in the drawing. Determine its degree (1°, 2°, 3°, or 4°) based on the number of carbon atoms directly attached to it: 1° (primary) has one carbon attached, 2° (secondary) has two carbons attached, 3° (tertiary) has three carbons attached, and 4° (quaternary) has four carbons attached.

Step 4: Verify your answers by carefully reviewing the structure and ensuring all bonds and atoms are accounted for. Double-check the number of hydrogens and the degree of the indicated carbon.

Step 5: Summarize your findings for each part of the question: (i) total number of carbons, (ii) number of hydrogens at the circled carbon, and (iii) degree of the indicated carbon.

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Key Concepts

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

Line-Angle Structures

Line-angle drawings, also known as skeletal structures, represent organic molecules in a simplified form where vertices and ends of lines indicate carbon atoms. Each carbon is assumed to have enough hydrogen atoms to satisfy its tetravalency, which is four bonds. Understanding this representation is crucial for quickly identifying the number of carbon atoms in a molecule.

Hydrogen Atoms and Valency

In organic chemistry, each carbon atom typically forms four bonds, which can include bonds with hydrogen atoms. The number of hydrogen atoms attached to a specific carbon can vary based on its bonding environment. Recognizing how to determine the number of hydrogens at a given carbon, especially when it is circled in a drawing, is essential for answering questions about molecular structure.

Carbon Hybridization and Degree Classification

Carbons in organic molecules can be classified based on their connectivity to other carbon atoms, leading to designations such as primary (1°), secondary (2°), tertiary (3°), and quaternary (4°). This classification is determined by how many other carbon atoms are directly bonded to a given carbon. Understanding this concept is vital for assessing the reactivity and properties of the molecule in question.

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Related Practice

Textbook Question

Compound X, isolated from lanolin (sheep's wool fat), has the pungent aroma of dirty sweatsocks. A careful analysis showed that compound X contains 62.0% carbon and 10.4% hydrogen. No nitrogen or halogen was found.

b. A molecular weight determination showed that compound X has a molecular weight of approximately 117. Find the molecular formula of compound X.

Textbook Question

Give the molecular formula of each compound shown

(a)

(b)

(c)

Textbook Question

Some of the following molecular formulas correspond to stable compounds. When possible, draw a stable structure for each formula. Propose a general rule for the numbers of hydrogen atoms in stable hydrocarbons.

Textbook Question

Convert the following hybrid structural formulas into the line-angle drawings.

(b)

Textbook Question

Identify the mistakes contained within the following structures.

(a)

Textbook Question

How many hydrogens are attached to each of the indicated carbons in morphine?

Textbook Question

How many hydrogens would you expect a 24-carbon compound from each of the following molecular classes to have?

(a) Alkane

Textbook Question