Atomic Structure and the Periodic TableAQA GCSE Chemistry: Topic test

20 questions, 54 marks

AQA GCSE Chemistry

Atomic Structure and the Periodic Table topic test

Total 54 marks

Name

Class

Date

1
A geologist is using potassium-argon dating to estimate the age of a volcanic rock sample. The method depends on the radioactive decay of the isotope potassium-40 into argon-40 over very long timescales. The sample contains potassium, atomic number 19, and argon, atomic number 18.
(a)
A neutral atom of potassium-40 has atomic number 19 and mass number 40. Which of the following correctly gives the numbers of protons, neutrons and electrons in this atom?
[1 mark]
A19 protons, 21 neutrons, 19 electrons
B19 protons, 19 neutrons, 19 electrons
C21 protons, 19 neutrons, 21 electrons
D19 protons, 21 neutrons, 21 electrons
(b)
Potassium-40 and potassium-39 are both found in nature. What term describes atoms of the same element that have different numbers of neutrons, such as these two forms of potassium?
[1 mark]
AIons
BIsotopes
CCompounds
DAllotropes
(c)
A sample of potassium contains two isotopes: 93.3% is potassium-39 and 6.7% is potassium-41. Calculate the relative atomic mass of this potassium sample, giving your answer to 3 significant figures. Show your working.
[2 marks]
Total for question 1: 4 marks
2
A semiconductor manufacturer dopes pure silicon crystals with tiny amounts of phosphorus to make them conduct electricity better. Silicon has atomic number 14 and phosphorus has atomic number 15. Engineers need to understand the electronic structures of these elements to explain why doping changes the material's properties.
(a)
Electrons in an atom occupy the lowest available energy levels. What term is commonly used for these energy levels?
[1 mark]
ANuclei
BIsotopes
CShells
DIons
(b)
Silicon has atomic number 14. What is the electronic structure of a silicon atom?
[1 mark]
A2,4,8
B2,8,2,2
C2,6,6
D2,8,4
(c)
Phosphorus has atomic number 15. Give the electronic structure of a phosphorus atom, and explain how the number of electrons in its outer shell relates to its position in the periodic table.
[2 marks]
Total for question 2: 4 marks
3
A battery research team is testing small samples of lithium and sodium metal, both stored under oil, for use in experimental high-capacity batteries. As part of their safety assessment, they drop a small piece of each metal into a trough of water and observe the reactions, before comparing the results with potassium, which they read about but do not test directly due to its extreme reactivity.
(a)
Describe what the researchers would observe when a small piece of lithium is added to water, and write a word equation for the reaction.
[3 marks]
(b)
The researchers find that sodium reacts more vigorously with water than lithium does, moving faster across the surface and sometimes melting into a small ball. Using the trend in reactivity down Group 1, explain why sodium reacts more vigorously than lithium, and predict how potassium would behave compared with both, referring to electronic structure.
[4 marks]
Total for question 3: 7 marks
4
A semiconductor cleanroom uses chlorine gas in one stage of manufacturing to etch fine patterns onto silicon wafers, because chlorine reacts readily with certain materials on the wafer surface. In a separate stage, the cleanroom fills chambers with argon gas to purge oxygen and moisture away from sensitive components while they are processed, because argon does not react with the wafer surface at all.
(a)
Explain, in terms of electronic structure, why chlorine is reactive and able to etch the wafer surface, and describe what would happen if bromine were used in the etching stage instead, referring to the trend in reactivity down Group 7.
[6 marks]
(b)
Explain, in terms of electronic structure, why argon is suitable for purging the chamber instead of a reactive gas, and discuss why neon or krypton, also in Group 0, would work similarly well for this purpose despite having very different boiling points from argon.
[6 marks]
Total for question 4: 12 marks
5
A structural engineer is comparing materials for the support beams of a new pedestrian bridge in a coastal town with humid, salty air. She is deciding between using a metal alloy and a composite based on a non-metal element, and wants to understand how an element's position in the periodic table relates to whether it behaves as a metal or a non-metal.
(a)
Metals are found on the left and towards the bottom of the periodic table, while non-metals are found on the right and towards the top. Which statement correctly explains this difference in terms of ions?
[1 mark]
AMetal atoms form positive ions by losing electrons; non-metal atoms do not typically form positive ions
BMetal atoms form negative ions by gaining electrons; non-metal atoms form positive ions
CBoth metals and non-metals form positive ions in the same way
DNeither metals nor non-metals form ions
(b)
The engineer notes that elements are arranged in the periodic table in a particular order. What determines the order in which elements are arranged, from left to right and top to bottom?
[1 mark]
AAlphabetical order of their names
BIncreasing atomic (proton) number
CDecreasing relative atomic mass
DThe year each element was discovered
(c)
Explain why elements in the same column (group) of the periodic table, such as the group containing carbon and silicon, tend to have similar chemical properties.
[2 marks]
Total for question 5: 4 marks
6
A school science technician is preparing a hands-on revision kit, using magnets and marbles, that lets students physically build three different historical models of the atom before comparing them with the model chemists use today.
(a)
The first kit represents atoms as solid, indivisible spheres, with no smaller parts inside. Which early scientist's model does this represent?
[1 mark]
ABohr's model
BThe nuclear model
CDalton's model
DThe plum pudding model
(b)
A second kit uses a sphere of positive charge with small negative marbles embedded throughout it, similar to fruit in a pudding. Which discovery led scientists to replace the solid sphere model with this model?
[1 mark]
AThe discovery of the nucleus
BThe discovery of the neutron
CThe discovery of isotopes
DThe discovery of the electron
(c)
A third kit shows a tiny, dense, positively charged centre with mostly empty space around it. Explain which experiment led scientists to propose this nuclear model, and what the result of the experiment showed.
[2 marks]
Total for question 6: 4 marks
7
A chemical company extracts bromine from concentrated seawater brine left over after salt production. Chlorine gas is bubbled through the brine, which contains dissolved bromide ions, to displace bromine from the solution, which is then collected as a valuable industrial chemical.
(a)
Explain, in terms of reactivity, why chlorine is able to displace bromine from a solution containing bromide ions, and write a word equation for the reaction.
[3 marks]
(b)
The company considers using iodine instead of chlorine to try to displace bromine from the same brine. Predict, with a reason, whether this would work, and describe one observation that would confirm whether a displacement reaction had occurred if chlorine gas is instead bubbled through a solution containing iodide ions.
[4 marks]
Total for question 7: 7 marks
8
A university chemistry department creates an interactive periodic table wall display for open days, where visitors press buttons to compare trends across different groups of elements, including Group 1, Group 0 and Group 7.
(a)
One part of the display lets visitors compare the reactivity of lithium, sodium and potassium with water. Explain fully why reactivity increases going down Group 1, from lithium to potassium, referring to electronic structure, atomic size and the force of attraction on the outer electron.
[6 marks]
(b)
A second part of the display compares the noble gases, showing that they are all unreactive regardless of position in the group, unlike Group 1 and Group 7 elements. Explain why every Group 0 element is similarly unreactive, and discuss why, despite this shared unreactivity, boiling point still changes noticeably down the group.
[6 marks]
Total for question 8: 12 marks

End of questions