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

3. Chemical Reactions

Naming Ionic Compounds

General Chemistry

3. Chemical Reactions

Naming Ionic Compounds

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Multiple Choice

Which of the following is the correct chemical formula for aluminum sulfide?

Al3S2

AlS

Al2S3

AlS3

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Verified step by step guidance

Step 1: Identify the charges of the ions involved. Aluminum typically forms a +3 charge ion, written as Al^{3+}, and sulfide forms a -2 charge ion, written as S^{2-}.

Step 2: To write the correct formula for aluminum sulfide, balance the total positive and negative charges so that the compound is electrically neutral.

Step 3: Use the crisscross method to balance charges: take the magnitude of the charge on the aluminum ion (3) and use it as the subscript for sulfur, and take the magnitude of the charge on the sulfide ion (2) and use it as the subscript for aluminum.

Step 4: Write the formula with the subscripts obtained: Al_{2}S_{3}, which means 2 aluminum atoms combine with 3 sulfur atoms to form aluminum sulfide.

Step 5: Verify that the total positive charge (2 × +3 = +6) balances the total negative charge (3 × -2 = -6), confirming the formula Al_{2}S_{3} is correct.