AQA GCSE Combined Science: Chemistry: Atomic Structure and the Periodic Table
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.
Our model of the atom has changed over time as scientists carried out new experiments and gathered new evidence.
Describe how the model of the atom developed from the idea of tiny indivisible spheres through to the nuclear model used today. In your answer you should refer to the plum pudding model, the alpha-particle scattering experiment, and the work that led to the idea of electron shells (energy levels) and the neutron.
(6 marks)
Chlorine exists as a mixture of two isotopes. Information about a sample of chlorine is shown in the table.
| Isotope | Mass number | Abundance in the sample / % |
|---|---|---|
| chlorine-35 | 35 | 75 |
| chlorine-37 | 37 | 25 |
(a) Explain what is meant by the term isotopes. (2 marks)
(b) Calculate the relative atomic mass of chlorine in this sample. Give your answer to one decimal place and show your working. (2 marks)
Sodium is in Group 1 of the periodic table. It reacts vigorously with water.
(a) Give the electronic structure of a sodium atom (atomic number 11). (1 mark)
(b) The word equation for the reaction of sodium with water is:
sodium + water → sodium hydroxide + hydrogen
Write the balanced symbol equation, including state symbols, for this reaction. (2 marks)
The halogens are the elements in Group 7 of the periodic table. Some data for three halogens are shown in the table.
| Halogen | State at room temperature | Colour |
|---|---|---|
| chlorine | gas | green |
| bromine | liquid | orange-brown |
| iodine | solid | grey-black (solid) |
(a) A more reactive halogen can displace a less reactive halogen from a solution of its salt. Predict whether chlorine will react with a solution of potassium bromide, and explain your answer using the trend in reactivity down Group 7. (2 marks)
(b) Write a balanced symbol equation for the reaction between chlorine and potassium bromide solution. (1 mark)
A student has a mixture of sand (an insoluble solid) and salt (sodium chloride, which is soluble in water). The student wants to obtain a pure, dry sample of the salt from the mixture.
Describe the steps the student should take to separate the salt from the sand and obtain it as a dry solid. (2 marks)
The elements in Group 0 of the periodic table are also called the noble gases.
State why the noble gases are very unreactive. (1 mark)