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

Lewis Structure

Organic Chemistry

1. A Review of General Chemistry

Lewis Structure

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4:57 minutes

Problem 30a

Textbook Question

Both PCl₃ and PCl₅ are stable compounds. Draw Lewis structures for these two compounds.

Verified step by step guidance

To draw the Lewis structure for PCl3, start by identifying the total number of valence electrons. Phosphorus (P) has 5 valence electrons, and each chlorine (Cl) has 7 valence electrons. Since there are three chlorine atoms, the total number of valence electrons is 5 + (3 * 7) = 26.

Place the phosphorus atom in the center as it is less electronegative than chlorine. Arrange the three chlorine atoms around the phosphorus atom.

Draw single bonds between the phosphorus atom and each chlorine atom. Each bond represents a pair of shared electrons, so this uses up 6 electrons (3 bonds * 2 electrons per bond).

Distribute the remaining 20 electrons as lone pairs around the chlorine atoms to satisfy the octet rule. Each chlorine atom should have 3 lone pairs (6 electrons) to complete its octet.

For PCl5, calculate the total number of valence electrons: Phosphorus has 5, and each of the five chlorine atoms has 7, giving a total of 5 + (5 * 7) = 40 valence electrons. Place phosphorus in the center and arrange the five chlorine atoms around it. Form single bonds between phosphorus and each chlorine, using 10 electrons. Distribute the remaining 30 electrons as lone pairs on the chlorine atoms, ensuring each chlorine has an octet.

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Key Concepts

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

Lewis Structures

Lewis structures are diagrams that represent the bonding between atoms of a molecule and the lone pairs of electrons that may exist. They are essential for visualizing the arrangement of electrons around atoms, which helps in predicting the shape, reactivity, and properties of the molecule. In drawing Lewis structures, it is important to account for all valence electrons and ensure that atoms achieve a stable electron configuration, often resembling the nearest noble gas.

Valence Electrons

Valence electrons are the outermost electrons of an atom and are crucial in determining how atoms interact and bond with each other. For phosphorus (P), which is in group 15 of the periodic table, there are five valence electrons. Understanding the number of valence electrons is key to drawing accurate Lewis structures, as it dictates how many bonds an atom can form and how many lone pairs it may have.

Octet Rule and Expanded Octet

The octet rule states that atoms tend to form bonds until they are surrounded by eight valence electrons, achieving a stable electron configuration. However, elements in period 3 and beyond, like phosphorus, can have an expanded octet, meaning they can hold more than eight electrons. This is due to the availability of d-orbitals, allowing compounds like PCl5 to exist with phosphorus having ten electrons in its valence shell.

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