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

Formal Charges

Organic Chemistry

1. A Review of General Chemistry

Formal Charges

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Problem 62u

Textbook Question

Draw the Lewis structure for the following molecular formulas.
(u) NH₄⁺

Verified step by step guidance

Step 1: Begin by identifying the total number of valence electrons in the molecule. Nitrogen (N) has 5 valence electrons, and each hydrogen (H) has 1 valence electron. Since the molecule has a positive charge (NH⁺₄), subtract 1 electron from the total count.

Step 2: Place the nitrogen atom at the center of the structure because it is less electronegative than hydrogen. Arrange the four hydrogen atoms around the nitrogen atom symmetrically.

Step 3: Draw single bonds between the nitrogen atom and each hydrogen atom. Each single bond represents 2 electrons, so account for these electrons in the total count.

Step 4: Check if the nitrogen atom has a complete octet (8 electrons) and if all hydrogen atoms have a complete duet (2 electrons). Since the molecule is positively charged, ensure the structure reflects the loss of one electron.

Step 5: Verify the formal charges on all atoms. The nitrogen atom should have a formal charge of +1, and the hydrogens should have a formal charge of 0. Ensure the overall charge of the molecule is +1, consistent with NH⁺₄.

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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 in a molecule and the lone pairs of electrons that may exist. They use dots to represent electrons and lines to represent bonds between atoms. Understanding how to draw Lewis structures is essential for visualizing molecular geometry and predicting the behavior of molecules in chemical reactions.

Valence Electrons

Valence electrons are the outermost electrons of an atom and are crucial for determining how atoms bond with each other. The number of valence electrons influences the molecule's reactivity and stability. For example, nitrogen has five valence electrons, which play a key role in forming bonds in compounds like NH₄⁺.

Formal Charge

Formal charge is a concept used to determine the distribution of electrons in a molecule and assess the stability of its Lewis structure. It is calculated by comparing the number of valence electrons in an isolated atom to the number of electrons assigned to it in the Lewis structure. A structure with the lowest formal charges on atoms is generally more stable, guiding the correct representation of molecules like NH₄⁺.

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