Question 1: Giant covalent structures are networks of atoms bonded together by covalent bonds, extending in three dimensions without the presence of individual molecules. Examples include diamond and graphite. These structures have unique properties due to their extensive bonding network.

Answer: Giant covalent structures are networks of atoms bonded covalently in a three-dimensional arrangement, forming a continuous structure without separate molecules.

Question 1: Define a giant covalent structure.

Answer: A structure where atoms are bonded covalently in a continuous three-dimensional network.

Question 2: Explain why diamond is extremely hard and has a high melting point.

Answer: Because each carbon atom is covalently bonded to four others in a rigid, three-dimensional network, requiring a lot of energy to break the bonds.

Question 3: What property of graphite makes it a good lubricant?

Answer: The layers in graphite are weakly bonded by Van der Waals forces, allowing them to slide over each other.

Question 1: Calculate the energy required to break all covalent bonds in 1 mole of diamond, given that each carbon-carbon bond requires 355 kJ/mol to break. Assume each carbon atom forms four bonds, but consider only the bonds to one atom for simplicity.

Answer: Energy = 355 kJ/mol * 4 = 1420 kJ

Question 1: Describe a simple experiment to demonstrate the high melting point of diamond compared to graphite, including the safety precautions you would take.

Answer: Heat small samples of diamond and graphite separately using a controlled high-temperature source such as a kiln or furnace, wearing heat-resistant gloves, eye protection, and ensuring good ventilation. Observe that diamond remains solid at higher temperatures than graphite, which sublimates or melts at lower temperatures.

Question 1: A sample of a giant covalent substance shows a very high melting point and is insoluble in water. Explain these observations based on its structure.

Answer: The high melting point indicates strong covalent bonds throughout the structure, requiring a lot of energy to break. Insolubility results from the network being too strong and extensive to dissolve in water.

Question 1: Explain how the properties of diamond make it suitable for use in cutting tools.

Answer: Diamond's extreme hardness and high durability due to its rigid covalent network make it ideal for cutting, grinding, and drilling.

Question 2: Describe a modern technological application that utilises a giant covalent structure and explain its function.

Answer: Graphene, a single layer of graphite, is used in flexible electronic devices due to its excellent electrical conductivity, strength, and flexibility resulting from its two-dimensional covalent network.