Question 1: Explain what is meant by a giant ionic lattice and describe its basic structure.

Answer: A giant ionic lattice is a three-dimensional structure composed of a regular arrangement of oppositely charged ions held together by strong electrostatic forces, forming a repeating pattern throughout the solid.

Question 1: Define ionic bonding and explain how it occurs between metal and non-metal elements.

Answer: Ionic bonding is the electrostatic attraction between oppositely charged ions, formed when a metal atom loses electrons to become a positively charged ion and a non-metal atom gains electrons to become negatively charged.

Question 2: What are the typical physical properties of substances with giant ionic lattices? List at least three.

Answer: They tend to have high melting and boiling points, are hard but brittle, and do not conduct electricity in solid form.

Question 1: Calculate the number of ions in 0.5 mol of sodium chloride (NaCl).

Answer: Number of ions = 0.5 mol × 2 (Na+ and Cl-) × 6.022 × 10^23 = 6.022 × 10^23 ions.

Question 2: The lattice energy of magnesium oxide (MgO) is approximately -3790 kJ/mol. Explain what this value indicates about the strength of the ionic bonds in MgO.

Answer: It indicates that the ionic bonds in MgO are very strong, requiring a large amount of energy to break the lattice apart.

Question 1: Describe a simple experiment to test the electrical conductivity of an ionic compound in its molten state.

Answer: You can heat a sample of the ionic compound until it melts and then connect it to a circuit with a bulb or voltmeter. If the bulb lights or the voltmeter shows a current, it indicates that the molten ionic compound conducts electricity due to free ions.

Question 2: List two safety precautions to consider when heating ionic compounds in a laboratory setting.

Answer: Use heat-resistant gloves and eye protection; ensure proper ventilation to avoid inhaling fumes.

Question 1: A sample of sodium chloride is heated until it melts and then cooled rapidly. Describe the expected changes in its crystal structure and properties.

Answer: Rapid cooling may lead to the formation of smaller, less orderly crystals, potentially making the solid more brittle and reducing its melting point slightly compared to a slowly cooled sample.

Question 2: If an ionic compound has a high melting point but low solubility in water, what does this suggest about its lattice energy and hydration energy?

Answer: It suggests that the lattice energy is very high, making it difficult for water molecules to break the lattice, and the hydration energy is relatively low.

Question 1: Explain why sodium chloride is used extensively in the food industry and in de-icing roads, based on its ionic properties.

Answer: Sodium chloride dissolves readily in water, conducts electricity in solution, and lowers the freezing point of water, making it useful for flavouring, preservation, and melting ice on roads.

Question 2: Discuss how understanding ionic lattices can contribute to developing new materials for electronics.

Answer: Knowledge of ionic lattice structures and properties helps in designing materials with specific electrical conductivity, stability, and durability for use in electronic devices, sensors, and batteries, by manipulating lattice energy and ion composition to optimise performance.