Atomic Structure and the Periodic TableEdexcel International A Level Chemistry: Topic test

20 questions, 54 marks

Edexcel International A Level Chemistry

Atomic Structure and the Periodic Table topic test

Total 54 marks

Name

Class

Date

1
Strontium-90, ⁹⁰Sr, is a radioactive isotope found in nuclear fallout. Strontium has atomic number 38 and forms Sr²⁺ ions that can replace Ca²⁺ ions in bone. A stable isotope of strontium is ⁸⁸Sr.
(a)
How many neutrons are in one ⁹⁰Sr²⁺ ion?
[1 mark]
A38
B90
C52
D128
(b)
How many electrons are in one ⁹⁰Sr²⁺ ion?
[1 mark]
A36
B38
C40
D52
(c)
Explain why ⁹⁰Sr and ⁸⁸Sr have the same chemical properties but different masses.
[2 marks]
Total for question 1: 4 marks
2
A chemist analyses bromine by mass spectrometry. Natural bromine contains two isotopes: ⁷⁹Br with abundance 50.7 % and ⁸¹Br with abundance 49.3 %. The sample is vaporised as Br₂ molecules.
(a)
Which statement describes the peaks produced by the molecular ions, Br₂⁺, in the mass spectrum?
[1 mark]
ATwo peaks, at m/z 158 and 162, with relative heights close to 1 : 1
BThree peaks, at m/z 158, 160 and 162, with relative heights close to 1 : 2 : 1
CTwo peaks, at m/z 79 and 81, with relative heights close to 1 : 1
DThree peaks, at m/z 158, 160 and 162, with relative heights close to 1 : 1 : 1
(b)
In the magnetic field of the mass spectrometer, which ions are deflected most?
[1 mark]
AIons with the largest mass, because they have more momentum
BIons with the smallest charge
CAll ions equally, because they all have the same speed
DIons with the smallest mass-to-charge ratio
(c)
Calculate the relative atomic mass of bromine from the data. Give your answer to 3 significant figures.
[2 marks]
Total for question 2: 4 marks
3
The first ionisation energies of the Period 2 elements, in kJ mol⁻¹, are: Li 520, Be 900, B 801, C 1086, N 1402, O 1314, F 1681 and Ne 2081.
(a)
Write an equation, with state symbols, for the first ionisation energy of oxygen. Define first ionisation energy, and explain why the process is endothermic.
[3 marks]
(b)
Explain why the first ionisation energy of oxygen is lower than that of nitrogen, and why that of boron is lower than that of beryllium.
[4 marks]
Total for question 3: 7 marks
4
Krypton is a noble gas with atomic number 36. Bromine (atomic number 35) and rubidium (atomic number 37) are close to it in the Periodic Table. The first ionisation energies, in kJ mol⁻¹, are: Br 1140, Kr 1351 and Rb 403.
(a)
Give the electronic configuration, in s, p, d notation, of a bromine atom, a bromide ion and a rubidium ion. Draw the electrons-in-boxes diagram for the 4p sub-shell of a bromine atom. Explain why Br⁻ and Rb⁺ are said to be isoelectronic with krypton and which of the two ions is smaller.
[6 marks]
(b)
Explain why the first ionisation energy of krypton is higher than that of bromine, and why that of rubidium is much lower than that of krypton.
[6 marks]
Total for question 4: 12 marks
5
Sulfur has atomic number 16. It forms sulfide ions, S²⁻, in many minerals.
(a)
What is the electronic configuration of the sulfide ion, S²⁻?
[1 mark]
A1s²2s²2p⁶3s²3p⁴
B1s²2s²2p⁶3s²3p²
C1s²2s²2p⁶3s²3p⁶3d²
D1s²2s²2p⁶3s²3p⁶
(b)
Which statement about the 3p sub-shell of an atom is correct?
[1 mark]
AIt contains one spherical orbital that holds up to six electrons
BIt contains three dumbbell-shaped orbitals, each holding up to two electrons
CIt contains three dumbbell-shaped orbitals, each holding up to two electrons of the same spin
DIt contains five dumbbell-shaped orbitals, each holding up to two electrons
(c)
The four 3p electrons in a ground-state sulfur atom are arranged ↑↓ ↑ ↑. Explain why they are not arranged ↑↓ ↑↓ with one orbital empty.
[2 marks]
Total for question 5: 4 marks
6
The first ionisation energies of the Group 14 elements, in kJ mol⁻¹, are: C 1086, Si 786, Ge 762 and Sn 709. Germanium has atomic number 32.
(a)
Which statement best explains why the first ionisation energy decreases down Group 14?
[1 mark]
AGreater shielding and a larger atomic radius outweigh the increase in nuclear charge
BThe nuclear charge decreases down the group
CThe number of outer electrons decreases down the group
DThe outer electron is in a different type of orbital in each element
(b)
Which sub-shell contains the highest-energy electrons in a ground-state germanium atom?
[1 mark]
A4s
B3d
C4p
D4d
(c)
The first ionisation energy is described as a periodic property. State what is meant by a periodic property, and describe how the first ionisation energy shows this across Period 3.
[2 marks]
Total for question 6: 4 marks
7
Boiling temperatures of some elements, in °C: sodium 883, magnesium 1090, silicon 3265, chlorine −34 and argon −186.
(a)
Explain why the boiling temperature of magnesium is higher than that of sodium.
[3 marks]
(b)
Explain why silicon has a much higher boiling temperature than chlorine, and why chlorine has a higher boiling temperature than argon.
[4 marks]
Total for question 7: 7 marks
8
Gallium, atomic number 31, is a metal used in semiconductors. Natural gallium contains two isotopes: ⁶⁹Ga with abundance 60.1 % and ⁷¹Ga with abundance 39.9 %. The first four ionisation energies of gallium, in kJ mol⁻¹, are 579, 1979, 2963 and 6180. The first ionisation energy of zinc, atomic number 30, is 906 kJ mol⁻¹.
(a)
Describe how a mass spectrometer is used to analyse a sample of gallium, and calculate the relative atomic mass of gallium from the data. Give your answer to 3 significant figures.
[6 marks]
(b)
Write an equation, with state symbols, for the third ionisation energy of gallium. Explain how the ionisation energies show that gallium is in Group 13, and why the first ionisation energy of gallium is lower than that of zinc.
[6 marks]
Total for question 8: 12 marks

End of questions

Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).