Predict the chemical formulas of the compounds formed by the following pairs of ions: (a) Cr³⁺ and CN^- (b) Mn²⁺ and ClO₄^-

Verified step by step guidance

1. Identify the charges on each ion: Mn^{2+} has a charge of +2, and ClO_4^{-} has a charge of -1.
2. To form a neutral compound, the total positive charge must balance the total negative charge.
3. Determine the ratio of ions needed to balance the charges: Since Mn^{2+} has a +2 charge and ClO_4^{-} has a -1 charge, you will need two ClO_4^{-} ions to balance one Mn^{2+} ion.
4. Write the chemical formula by placing the cation first followed by the anion, using subscripts to indicate the number of each ion needed: Mn(ClO_4)_2.
5. Ensure the compound is neutral: Verify that the total positive charge (+2 from Mn^{2+}) equals the total negative charge (-2 from two ClO_4^{-} ions).

Key Concepts

Ionic Compounds

Ionic compounds are formed when cations (positively charged ions) and anions (negatively charged ions) bond together through electrostatic forces. The overall charge of the compound must be neutral, meaning the total positive charge from the cations must balance the total negative charge from the anions.

Charge Balance

Charge balance is a fundamental principle in forming ionic compounds. Each ion has a specific charge, and when combining ions, the total positive charge must equal the total negative charge. For example, in the case of Mn2+ and ClO4-, the Mn2+ ion has a +2 charge, which must be balanced by two ClO4- ions, each with a -1 charge.

Polyatomic Ions

Polyatomic ions are ions composed of two or more atoms covalently bonded together, which carry a net charge. In this case, ClO4- is a polyatomic ion known as perchlorate. Understanding the structure and charge of polyatomic ions is essential for predicting the formulas of compounds they form with other ions.