Table of contents

1. Matter and Measurements4h 29m
2. Atoms and the Periodic Table5h 23m
3. Ionic Compounds2h 18m
4. Molecular Compounds2h 18m
5. Classification & Balancing of Chemical Reactions3h 17m
6. Chemical Reactions & Quantities2h 35m
7. Energy, Rate and Equilibrium3h 46m
8. Gases, Liquids and Solids3h 25m
9. Solutions4h 10m
10. Acids and Bases3h 29m
11. Nuclear Chemistry56m
BONUS: Lab Techniques and Procedures1h 38m
BONUS: Mathematical Operations and Functions47m
12. Introduction to Organic Chemistry1h 34m
13. Alkenes, Alkynes, and Aromatic Compounds2h 12m
14. Compounds with Oxygen or Sulfur1h 6m
15. Aldehydes and Ketones1h 1m
16. Carboxylic Acids and Their Derivatives1h 11m
17. Amines38m
18. Amino Acids and Proteins1h 51m
19. Enzymes1h 37m
20. Carbohydrates1h 46m
21. The Generation of Biochemical Energy2h 8m
22. Carbohydrate Metabolism2h 22m
23. Lipids2h 26m
24. Lipid Metabolism1h 45m
25. Protein and Amino Acid Metabolism1h 37m
26. Nucleic Acids and Protein Synthesis2h 54m

3. Ionic Compounds

Writing Formula Units of Ionic Compounds

GOB Chemistry

3. Ionic Compounds

Writing Formula Units of Ionic Compounds

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1:24 minutes

Problem 18Timberlake - 13th Edition

Textbook Question

Write the correct ionic formula for the compound formed between each of the following pairs of ions: b. Ca²⁺ and S²⁻

Verified step by step guidance

Identify the charges on each ion: Calcium (Ca) has a charge of +2, and Sulfur (S) has a charge of -2.

To form a neutral compound, the total positive charge must balance the total negative charge.

Since both ions have charges of equal magnitude but opposite signs (+2 and -2), they will combine in a 1:1 ratio.

Write the formula by placing the symbols for calcium and sulfur together, without any subscripts, as the charges are already balanced.

The correct ionic formula for the compound is CaS.

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Key Concepts

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

Ionic Compounds

Ionic compounds are formed when positively charged ions (cations) and negatively charged ions (anions) bond together through electrostatic forces. The overall charge of the compound must be neutral, meaning the total positive charge must balance the total negative charge. Understanding how these charges interact is essential for writing correct ionic formulas.

Charge Balance

Charge balance is a fundamental principle in forming ionic compounds. Each ion carries a specific charge, and when combining ions, the total positive charge from cations must equal the total negative charge from anions. For example, in the case of Ca²⁺ (which has a +2 charge) and S²⁻ (which has a -2 charge), one of each ion combines to create a neutral compound.

Chemical Formula Representation

The chemical formula of an ionic compound represents the ratio of ions in the compound. It is typically written with the cation first followed by the anion. For the compound formed from Ca²⁺ and S²⁻, the formula is CaS, indicating a 1:1 ratio of calcium ions to sulfide ions, which reflects the balance of charges.