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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