An atom with a formal charge does not necessarily have more or less electron density than the atoms in the molecule without formal charges. We can see this by examining the potential maps for H 2 O, H 3 O + , and HO − . <IMAGE> c. Which atom bears the formal positive charge in the hydronium ion? d. Which atom has the least electron density in the hydronium ion?

Alright. Hi, everyone. So for this question, it says that by examining the potential maps for NH three NH four plus an NH two minus, we can see that an atom with a formal charge does not always have a higher or lower electron density than the atoms in the molecule with no formal charges. So for part one is asking us which Adam carries the formal positive charge in NH four plus. And then part two is asking us which Adam has the least electron density in NH four plus. So to start us off with part one Let's go ahead and begin by drawing the Lewis structure for NH four plus. So our first step if you recall is to determine the total number of valence electrons in our chemical formula, right? So nitrogen is going to have A total of five and each nitrogen is going sorry, each hydrogen is going to have one. So that's five plus four is equal to nine, but we have to subtract one because of that positive charge. So -1 equals eight valence electrons. So now what we do for a Lewis structure is we start off by drawing the atom with the highest bond preference in the middle, which in this case is hydrogen. And we start off by proposing a sigma bond framework, right. So that means that our remaining atoms in this case are hydrogen Are going to be bonded to our nitrogen via 1 σ bond each. So if we count our total number of electrons, we do, in fact, end up with the eight valence electrons that we have for our Lewis structure. So now let's calculate the formal charge which I'm gonna abbreviate as FC on the screen. And our formal charge is equal to the number of valence electrons minus the number of non bonding electrons. Well spelled that wrong minus the number of non bonding electrons minus the number of bonding electrons divided by two. Mhm. So if I scroll down to give myself some space, let's start off by drawing or rather calculating the formal charge of nitrogen. Alright. So nitrogen here is going to be Our surveillance electrons is five, we have zero non bonding electrons because we have zero loan pairs and we have eight bonding electrons because our nitrogen participates in four single bonds, Right? So that's gonna be eight divided by two. So that's going to equal 5 -4, which means that we have a positive charge of plus one, right. So for hydrogen, hydrogen has just one valence electron, we have zero loan pairs. So that's zero non bonding electrons. And we have Two bonding electrons because we have one signal bond for each divided by two, right. So that's 1 -1, which equals to zero. So for part one it's gonna be nitrogen that carries the formal positive charge. So in blue on the side here, I'm gonna go ahead and write that for part one, the atom that carries a formal positive charge is going to be nitrogen. Now, for part two, it's asking us which atom has the least electron density in NH four plus. And we can look at that by noticing the colors of our electrostatic potential maps, right? So recall it in an electrostatic potential map. Dark blue areas correspond to areas with more positive electrostatic potential, which means that we have less electron density, Right? So if we look at the potential map for NH four plus in the center here, our dark blue areas are actually concentrated around our hydrogen, not our nitrogen in the center, right. So because our hydrogen are in the dark blue areas of our potential map, they have the more positive electrostatic potential and therefore the least electron density. So for part two, that's going to correspond to hydrogen having the least electron density and this is going to correspond to option a within the multiple choice. So this is going to be your final answer. And with that being said, thank you very much for watching. And I hope you found this helpful

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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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5:46 minutes

Problem 15c,d

Textbook Question

An atom with a formal charge does not necessarily have more or less electron density than the atoms in the molecule without formal charges. We can see this by examining the potential maps for H₂O, H₃O⁺, and HO⁻.
<IMAGE>
c. Which atom bears the formal positive charge in the hydronium ion?
d. Which atom has the least electron density in the hydronium ion?

Verified step by step guidance

Step 1: Understand the hydronium ion (H3O+). It consists of one oxygen atom bonded to three hydrogen atoms, with a formal positive charge distributed across the molecule.

Step 2: To determine which atom bears the formal positive charge in H3O+, recall that the formal charge is typically assigned to the atom that has fewer electrons than its neutral state. In H3O+, the oxygen atom has a formal positive charge because it has one less lone pair compared to neutral water (H2O).

Step 3: To identify the atom with the least electron density in H3O+, consider the electronegativity of the atoms. Oxygen is more electronegative than hydrogen, so it pulls electron density toward itself. However, the formal positive charge on oxygen reduces its electron density compared to neutral oxygen in H2O.

Step 4: Examine the molecular potential map for H3O+ (if provided). The atom with the least electron density will appear in the region with the most positive potential (blue regions in potential maps). This corresponds to the oxygen atom in H3O+.

Step 5: Summarize: In H3O+, the oxygen atom bears the formal positive charge and has the least electron density due to its formal charge and electronegativity effects.

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Key Concepts

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

Formal Charge

Formal charge is a theoretical charge assigned to an atom in a molecule, calculated based on the number of valence electrons, the number of bonds, and the number of non-bonding electrons. It helps in understanding the distribution of electrons within a molecule and predicting the stability of different resonance structures. A formal charge does not necessarily correlate with the actual electron density around an atom.

Electron Density

Electron density refers to the probability of finding electrons in a given region of space around an atom or molecule. It is visualized using potential maps, where areas of high electron density are often represented in blue, indicating regions where electrons are more likely to be found. Understanding electron density is crucial for predicting molecular behavior, reactivity, and the distribution of charges within a molecule.

Hydronium Ion (H3O+)

The hydronium ion (H3O+) is formed when a water molecule (H2O) accepts a proton (H+). In this ion, the oxygen atom carries a formal positive charge due to the addition of the proton, which alters the electron density around it. Analyzing the electron density in H3O+ compared to neutral water helps illustrate how formal charges can affect molecular properties without necessarily changing the overall electron density distribution.

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