A portion of a two-dimensional 'slab' of NaCl(s) is shown here (see Figure 8.2) in which the ions are numbered. (a) Which colored balls must represent sodium ions?

Key Concepts

Ionic Compounds

Ionic compounds, like sodium chloride (NaCl), are formed from the electrostatic attraction between positively charged cations and negatively charged anions. In NaCl, sodium (Na⁺) is the cation, while chloride (Cl⁻) is the anion. Understanding the nature of these ions is crucial for identifying their representation in a given structure.

Crystal Lattice Structure

The crystal lattice structure of ionic compounds is a three-dimensional arrangement of ions that maximizes attractive forces and minimizes repulsive forces. In NaCl, each sodium ion is surrounded by six chloride ions and vice versa, creating a repeating pattern. Recognizing this arrangement helps in visualizing how ions are positioned in the solid state.

Ion Representation in Models

In models of ionic compounds, different colors or shapes are often used to represent different ions. For example, sodium ions may be represented by one color, while chloride ions are represented by another. Identifying which colored balls correspond to sodium ions requires understanding the typical conventions used in such representations.