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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Problem 46e

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°?
(e)

Verified step by step guidance

Step 1: Count the number of carbons in the molecule. In a line-angle drawing, each vertex represents a carbon atom. For the given cyclic structure, count the vertices to determine the total number of carbons.

Step 2: Determine the number of hydrogens at the circled carbon. In a line-angle drawing, hydrogens are implied based on the number of bonds a carbon atom has. Carbon typically forms four bonds, so subtract the number of bonds shown from four to find the number of hydrogens attached to the circled carbon.

Step 3: Analyze the indicated (arrowed) carbon to determine its degree. The degree of a carbon atom is based on the number of other carbon atoms it is directly bonded to: 1° (primary) for one bond, 2° (secondary) for two bonds, 3° (tertiary) for three bonds, and 4° (quaternary) for four bonds.

Step 4: Verify the structure and ensure all implied hydrogens and bonds are accounted for. Double-check the circled and indicated carbons to confirm their properties.

Step 5: Summarize the findings for each part of the question: (i) total carbons, (ii) 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 Drawings

Line-angle drawings, also known as skeletal structures, are a shorthand representation of organic molecules. In these drawings, vertices represent carbon atoms, and the ends of lines represent carbon atoms as well. Hydrogen atoms are typically omitted for clarity, as they are implied based on the carbon's tetravalency. Understanding this notation is crucial for determining the number of carbons and hydrogens in a molecule.

Degree of Carbon

The degree of a carbon atom refers to the number of other carbon atoms it is directly bonded to. A carbon can be classified as primary (1°), secondary (2°), tertiary (3°), or quaternary (4°) based on this bonding. This classification affects the reactivity and properties of the molecule, making it essential to identify the degree of the indicated carbon in the question.

Hydrogen Count at a Carbon

The number of hydrogen atoms attached to a carbon atom depends on its degree and the presence of other substituents. A carbon atom typically forms four bonds; thus, a primary carbon (1°) is bonded to one other carbon and has three hydrogens, while a tertiary carbon (3°) is bonded to three other carbons and has only one hydrogen. Accurately counting the hydrogens at the circled carbon is vital for understanding the molecule's structure.