Table of contents

1. Intro to General Chemistry3h 48m
2. Atoms & Elements4h 16m
3. Chemical Reactions4h 10m
4. BONUS: Lab Techniques and Procedures1h 38m
5. BONUS: Mathematical Operations and Functions48m
6. Chemical Quantities & Aqueous Reactions3h 53m
7. Gases3h 49m
8. Thermochemistry2h 37m
9. Quantum Mechanics2h 58m
10. Periodic Properties of the Elements3h 9m
11. Bonding & Molecular Structure3h 29m
12. Molecular Shapes & Valence Bond Theory1h 57m
13. Liquids, Solids & Intermolecular Forces2h 23m
14. Solutions3h 1m
15. Chemical Kinetics2h 53m
16. Chemical Equilibrium2h 29m
17. Acid and Base Equilibrium5h 1m
18. Aqueous Equilibrium4h 47m
19. Chemical Thermodynamics1h 50m
20. Electrochemistry2h 42m
21. Nuclear Chemistry2h 36m
22. Organic Chemistry5h 7m
23. Chemistry of the Nonmetals2h 39m
24. Transition Metals and Coordination Compounds3h 16m

10. Periodic Properties of the Elements

Valence Electrons of Elements

General Chemistry

10. Periodic Properties of the Elements

Valence Electrons of Elements

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Multiple Choice

Which of the following is the correct number of valence electrons in NH3, and which Lewis structure best represents the molecule?

NH3 has 8 valence electrons; the Lewis structure shows nitrogen with a double bond to one hydrogen and single bonds to the other two hydrogens.

NH3 has 8 valence electrons; the Lewis structure shows nitrogen with three single bonds to hydrogens and one lone pair.

NH3 has 5 valence electrons; the Lewis structure shows nitrogen with three single bonds to hydrogens and one lone pair.

NH3 has 6 valence electrons; the Lewis structure shows nitrogen with three single bonds to hydrogens and no lone pairs.

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Verified step by step guidance

Step 1: Determine the total number of valence electrons in NH3 by adding the valence electrons of nitrogen and hydrogen atoms. Nitrogen is in group 15 and has 5 valence electrons, and each hydrogen has 1 valence electron. So, total valence electrons = 5 (N) + 3 × 1 (H) = 8 electrons.

Step 2: Use the total valence electrons to draw the Lewis structure. Place nitrogen as the central atom because it is less electronegative than hydrogen and can form multiple bonds.

Step 3: Connect each hydrogen atom to nitrogen with a single bond. Each single bond represents 2 electrons, so 3 single bonds use 6 electrons.

Step 4: Distribute the remaining electrons as lone pairs on the nitrogen atom. Since 6 electrons are used in bonds, 8 - 6 = 2 electrons remain, which form one lone pair on nitrogen.

Step 5: Verify the Lewis structure by checking that nitrogen has an octet (8 electrons total: 6 bonding + 2 lone pair) and each hydrogen has 2 electrons (a full shell for hydrogen). This confirms the correct Lewis structure is nitrogen with three single bonds to hydrogens and one lone pair.