Cobalt and Ionic Compounds Concepts

The video tutorial explains how to write the formula for cobalt(III) sulfide. It begins by identifying the element symbols for cobalt and sulfur, then discusses the ionic charges of these elements. The tutorial uses the crisscross method to derive the formula Co2S3, ensuring the compound is neutral. Finally, it verifies the formula by checking the charges, confirming the net charge is zero.

What is the symbol for cobalt as it appears on the periodic table?

• Co

• Cb

• Ct

• Cl

What charge does cobalt have in cobalt(III) sulfide?

• 4+

• 3+

• 2+

• 1+

What is the charge of the sulfide ion?

• 1-

• 2-

• 3-

• 4-

Why do the charges in cobalt(III) sulfide need to add up to zero?

• Because it is a covalent compound

• Because it is a molecular compound

• Because it is an ionic compound

• Because it is a metallic compound

What is the purpose of using the crisscross method?

• To calculate molar mass

• To find the atomic mass

• To determine the formula of ionic compounds

• To balance chemical equations

What is the formula for cobalt(III) sulfide?

• CoS2

• Co3S2

• Co2S3

• CoS

How do you verify that the formula Co2S3 is correct?

• By checking the atomic numbers

• By using a calculator

• By ensuring the charges add up to zero

• By comparing with other compounds