The following diagram represents an ionic compound in which the red spheres represent cations and the blue spheres represent anions. Which of the following compounds is consistent with the drawing?
a. potassium bromide
b. potassium sulfate
c. calcium nitrate
d. iron(III) sulfate

Verified step by step guidance

1. Identify the charge of the cations and anions typically found in each of the listed compounds. Potassium (K) typically forms K+ ions, bromide (Br) forms Br- ions, sulfate (SO4) forms SO4^2- ions, calcium (Ca) forms Ca^2+ ions, nitrate (NO3) forms NO3^- ions, and iron(III) (Fe) forms Fe^3+ ions.
2. Examine the stoichiometry of each compound to determine the ratio of cations to anions. Potassium bromide has a 1:1 ratio, potassium sulfate has a 2:1 ratio of potassium to sulfate, calcium nitrate has a 1:2 ratio of calcium to nitrate, and iron(III) sulfate has a 2:3 ratio of iron to sulfate.
3. Compare the ratio of red spheres (cations) to blue spheres (anions) in the diagram to the ratios in each compound option.
4. Consider the size and arrangement of the ions in a typical ionic lattice for each compound. Larger ions often occupy different positions in the lattice compared to smaller ions.
5. Select the compound whose typical ionic ratio and lattice arrangement best matches the diagram provided.

Key Concepts

Ionic Compounds

Ionic compounds are formed through the electrostatic attraction between cations (positively charged ions) and anions (negatively charged ions). These compounds typically consist of metals that lose electrons to become cations and nonmetals that gain electrons to become anions. Understanding the nature of these ions is crucial for identifying the correct compound represented in the diagram.

Charge Balance

In ionic compounds, the total positive charge from cations must balance the total negative charge from anions to achieve electrical neutrality. This means that the ratio of cations to anions is determined by their respective charges. For example, in potassium bromide (KBr), one potassium ion (K+) balances one bromide ion (Br-), while in potassium sulfate (K2SO4), two potassium ions balance one sulfate ion (SO4^2-).

Common Ionic Compounds

Familiarity with common ionic compounds and their formulas is essential for identifying the correct answer. For instance, potassium bromide (KBr) consists of K+ and Br-, while calcium nitrate (Ca(NO3)2) contains Ca2+ and two NO3- ions. Recognizing these compounds and their ionic structures helps in determining which one aligns with the provided diagram of cations and anions.