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?

Verified step by step guidance

1. Step 1: Understand the structure of NaCl. NaCl is an ionic compound composed of sodium ions (Na^+) and chloride ions (Cl^-).
2. Step 2: Recognize the charge of each ion. Sodium ions carry a positive charge (+1), while chloride ions carry a negative charge (-1).
3. Step 3: Consider the arrangement in a crystal lattice. In a NaCl crystal lattice, each sodium ion is surrounded by chloride ions and vice versa, forming a repeating pattern.
4. Step 4: Identify the color coding. Typically, in diagrams, different colors are used to represent different ions. Sodium ions and chloride ions will be represented by different colors.
5. Step 5: Determine which colored balls represent sodium ions. Look for the pattern where each sodium ion is surrounded by chloride ions, and identify the color that fits this description.

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.