Log out Go to App
Go to App

Learning Materials

Features

Discover

Chapter 4: Problem 146

Why is the formula for calcium sulfide \(\mathrm{CaS}\) and not \(\mathrm{Ca}_{2} \mathrm{~S} ?\)

Short Answer

Expert verified
The formula for calcium sulfide is CaS because the valencies of calcium (+2) and sulfur (-2) balance each other without the need for a subscript. This is determined by understanding valency and elements' combining capacity. Calcium loses 2 electrons and sulfur gains 2 electrons, resulting in a stable compound with electrical neutrality.

Step by step solution

01

Understanding Valency

Valency is the measure of an element's combining capacity with other elements to form compounds. It's determined by the number of electrons an element can gain, lose, or share in order to achieve a stable electronic configuration (a full outer shell of electrons).
02

Identifying the Valency of Calcium and Sulfur

Calcium (Ca) belongs to Group 2 of the periodic table, which means it has 2 valence electrons. Calcium's valency is +2, since it prefers to lose these 2 electrons to achieve a stable electronic configuration with a full outer shell. Sulfur (S) belongs to Group 16 of the periodic table, which means it has 6 valence electrons. Sulfur requires 2 more electrons to achieve a stable electronic configuration, so its valency is -2.
03

Applying the Valency Rule to Form the Compound

When elements combine to form a compound, their valencies should be balanced to maintain electrical neutrality in the compound. To do this, we can use the 'cross-over rule' or simply swap the valency numbers of the elements. Calcium (Ca) has a valency of +2, while sulfur (S) has a valency of -2. When we cross over the valencies, we use the absolute value of the valency and write the compound as: Calcium Sulfide: Ca (with subscript 2) S (with subscript 2) However, since the valency numbers (2) are the same, we can simplify this by removing the subscripts 2: Calcium Sulfide: CaS
04

Conclusion

The formula for calcium sulfide is CaS and not Ca₂S because the valencies of calcium and sulfur balance each other without the need for a subscript in their chemical formula. By understanding the concept of valency and combining capacity, we can determine the correct formula for compounds.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Start your free trial

Over 30 million students worldwide already upgrade their learning with Vaia!

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

Why are roman-numeral group numbers for the representative elements useful in predicting how many electrons an atom will gain or lose in a chemical reaction?

Predict the formula for the compound aluminum nitride made from the elements aluminum and nitrogen, and explain how you made your prediction.

Write electron configurations for \(\mathrm{O}, \mathrm{O}^{2+}\), and \(\mathrm{O}^{2-}\). Which form would you expect to find in most compounds of oxygen? Why?

Arrange \(\mathrm{Ca}, \mathrm{Se}, \mathrm{F}, \mathrm{S}\), and \(\mathrm{Rb}\) in order of increasing ionization energy.

What are the wavelength in nanometers and energy in joules of the light emitted when a hydrogen electron originally in the \(n=6\) shell relaxes to the ground state? \(\left[1 \mathrm{eV}=1.602 \times 10^{-19} \mathrm{~J}\right]\)
See all solutions

Recommended explanations on Chemistry Textbooks

Nuclear Chemistry

Read Explanation

Physical Chemistry

Read Explanation

Inorganic Chemistry

Read Explanation

Chemical Analysis

Read Explanation

Chemical Reactions

Read Explanation

Kinetics

Read Explanation
View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.

Sign-up for free