AQA GCSE Combined Science: Chemistry: Bonding, Structure and the Properties of Matter
6 exam-style questions with full mark schemes and model answers. Write your own answer and the AI examiner marks it against the mark scheme.
Diamond and graphite are both forms of the element carbon, yet they have very different properties. Diamond is extremely hard and does not conduct electricity, while graphite is soft and slippery and does conduct electricity.
Explain, in terms of their structure and bonding, why diamond and graphite have these different properties. (6 marks)
The table gives the melting points and boiling points of four substances, A, B, C and D.
| Substance | Melting point / °C | Boiling point / °C | Conducts electricity when solid? | Conducts electricity when molten? |
|---|---|---|---|---|
| A | −101 | −35 | no | no |
| B | 801 | 1413 | no | yes |
| C | 1085 | 2562 | yes | yes |
| D | 3550 | 4827 | no | no |
(a) Substance A has a very low melting point and does not conduct electricity in any state. State the type of structure A has, and explain what its low melting point tells you about the forces present. (2 marks)
(b) Use the data to identify which substance is an ionic compound and which is a metal, giving a reason in each case. (2 marks)
Magnesium oxide is an ionic compound. It is formed when magnesium reacts with oxygen.
(a) Describe how a magnesium atom and an oxygen atom form ions when magnesium oxide is made, including the charges on the ions formed. (2 marks)
(b) Write the balanced symbol equation, including state symbols, for the reaction of magnesium with oxygen to form magnesium oxide. (1 mark)
Metals such as copper are good conductors of electricity and can be bent and shaped without breaking.
(a) Describe the structure and bonding in a metal such as copper. (2 marks)
(b) Explain why metals are able to conduct electricity. (1 mark)
Nanoparticles are used as catalysts and in some sun creams. A nanoparticle is much smaller than a normal particle of the same material.
Explain why nanoparticles can be effective even when only a very small mass of material is used. (2 marks)
When a solid is heated until it melts, its particles gain energy.
Name the change of state that occurs when a liquid turns into a gas at its boiling point. (1 mark)