Ionic Compounds:

• Formed by the transfer of electrons between metals (which form cations) and non-metals (which form anions).
• Held together by strong electrostatic forces of attraction.

Crystal Lattice Structure:

• Ionic compounds arrange in a three-dimensional lattice structure to minimize energy and maximize stability.

• The structure ensures a balanced charge with alternating positive and negative ions.

Examples of Ionic Compounds:

• Sodium chloride (NaCl): Each Na⁺ ion is surrounded by six Cl⁻ ions and vice versa in a cubic lattice.

• Magnesium oxide (MgO): Arranged in a similar lattice with higher attraction due to 2+ and 2− charges.

Key Properties of Ionic Arrangement:

• High Melting and Boiling Points: Strong ionic bonds in the lattice require significant energy to break.
• Brittleness: When force is applied, ions of like charge come closer, causing repulsion and fracture.

• Electrical Conductivity: Ionic compounds conduct electricity in molten or aqueous states due to the free movement of ions.

Coordination Number:

• Represents the number of oppositely charged ions surrounding a given ion.
• Example: In NaCl, the coordination number is 6.

Factors Influencing Arrangement:

• Ionic Size: Smaller ions pack more tightly.
• Ionic Charge: Higher charges create stronger attractions and tighter lattices.
• Ration of Ion Sizes: Determines the type of lattice (e.g., cubic, hexagonal).

Lattice Energy:

• The energy released when one mole of an ionic compound forms from its gaseous ions.
• Determines the stability of the crystal lattice.

Importance of Lattice Structures:

• Explains properties like solubility, hardness, and conductivity.