Question

question 4. match the following pairs of ions with the correct chemical formulas of the compounds that they form:
a) ba²⁺, s²⁻
b) ca²⁺, n³⁻
c) cu²⁺, i⁻
:: bas₂ :: ba₂s :: ba₂s₂
:: bas :: ca₂n₃ :: ca₃n₂
:: ca₂n₂ :: ca₃n₃ :: cu₂i
:: cui₂ :: cui :: cu₂i₂

Explanation:

Step1: Solve for a) \( \text{Ba}^{2+}, \text{S}^{2-} \)

To form a neutral compound, the total positive charge must equal the total negative charge. The charge of \( \text{Ba}^{2+} \) is \( +2 \) and \( \text{S}^{2-} \) is \( -2 \). The ratio of \( \text{Ba}^{2+} \) to \( \text{S}^{2-} \) is \( 1:1 \) (since \( 2 = 2 \)). So the formula is \( \text{BaS} \).

Step2: Solve for b) \( \text{Ca}^{2+}, \text{N}^{3-} \)

Let the formula be \( \text{Ca}_x\text{N}_y \). The total positive charge is \( 2x \), total negative charge is \( 3y \). For neutrality, \( 2x = 3y \). The smallest integers satisfying this are \( x = 3 \), \( y = 2 \) (since \( 2\times3 = 3\times2 = 6 \)). So the formula is \( \text{Ca}_3\text{N}_2 \).

Step3: Solve for c) \( \text{Cu}^{2+}, \text{I}^- \)

Let the formula be \( \text{Cu}_x\text{I}_y \). Total positive charge: \( 2x \), total negative charge: \( 1\times y \). For neutrality, \( 2x = y \). The smallest integers: \( x = 1 \), \( y = 2 \). So the formula is \( \text{CuI}_2 \).

Answer:

a) \( \text{Ba}^{2+}, \text{S}^{2-} \): \( \text{BaS} \)
b) \( \text{Ca}^{2+}, \text{N}^{3-} \): \( \text{Ca}_3\text{N}_2 \)
c) \( \text{Cu}^{2+}, \text{I}^- \): \( \text{CuI}_2 \)