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.
Learn this properly: Ionic BondingDiamond and graphite are both forms of the element carbon. They have very different properties: diamond is extremely hard and does not conduct electricity, whereas graphite is soft, slippery and conducts electricity.
Explain, in terms of their structure and bonding, why diamond and graphite have these different properties. (6 marks)
Magnesium chloride is an ionic compound. A magnesium atom (electronic structure 2,8,2) reacts with chlorine atoms (electronic structure 2,8,7).
(a) Describe, in terms of electron transfer, what happens when magnesium reacts with chlorine to form magnesium chloride. Give the charges on the ions formed and the formula of magnesium chloride. (3 marks)
(b) Solid magnesium chloride does not conduct electricity, but molten magnesium chloride does. Explain why. (1 mark)
Metals are good conductors of electricity and are malleable (they can be bent and shaped without shattering).
(a) Describe the structure and bonding in a metal. (2 marks)
(b) Use your answer to explain why metals are good conductors of electricity. (1 mark)
The table gives the melting points and electrical conductivity (when solid) of four substances, A–D.
| Substance | Melting point / °C | Conducts when solid? |
|---|---|---|
| A | −182 | No |
| B | 801 | No |
| C | 1085 | Yes |
| D | 3550 | No |
One substance is a small covalent molecule, one is a giant ionic compound, one is a metal, and one is a giant covalent structure (like diamond).
(a) Identify which substance, A–D, is the small molecule, and explain your choice. (2 marks)
(b) Identify which substance, A–D, is the metal. (1 mark)
A nanoparticle is a very small particle, between 1 and 100 nanometres (nm) in size.
Consider a cube-shaped nanoparticle with sides of length 10 nm.
(a) Calculate the surface-area-to-volume ratio of this cube. Show your working. (2 marks)
(For a cube of side l: surface area =6l2 and volume =l3.)
Carbon dioxide, CO2, is a small molecule. The atoms within a molecule of carbon dioxide are held together by covalent bonds.
State what is meant by a covalent bond. (1 mark)