A Level Cambridge (CIE)
Chemistry
49 mins
6 questions
Structured Questions
Particles in the Atom
& Atomic Radius
Atomic Structure & Subatomic Particles / Determining Subatomic Structure /
Variations in Atomic & Ionic Radius
Easy (2 questions)
/16
Medium (3 questions)
/23
Hard (1 question)
/10
Total Marks
/49
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1
Easy Questions
1 (a) Complete Table 1.1 to show the relative charge and mass of the subatomic particles.
Table 1.1
Subatomic particle
Relative Charge
Proton
Relative Mass
1
Neutron
Electron
1
1836
(4 marks)
(b) Using the Periodic Table, complete Table 1.2 to show the number of protons, neutrons
and electrons in each of the given species.
Table 1.2
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Species
Number of protons
Number of neutrons
Number of electrons
31P
24Na+
37Cl–
(3 marks)
(c) State why the physical properties of isotopes are different.
(2 marks)
(d) Explain why the chemical properties of 35Cl and 37Cl are similar.
(2 marks)
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2 (a) Fig. 5.1 shows how protons, neutrons and electrons behave differently when they move
at the same velocity in an electric field.
Label the positive and negative plates in Fig. 5.1.
Fig. 5.1
(1 mark)
(b) Using the Periodic Table, complete Table 5.1 to show the number of protons, neutrons
and electrons in each of the given species.
Table 5.1
Symbol
23
Protons
Neutrons
Electrons
Na
32S2–
86Sr2+
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(3 marks)
(c) Write the electronic configuration for the 32S2– atom.
(1 mark)
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Medium Questions
1 (a) The Bohr model of an atom represents a central nucleus, consisting of protons and
neutrons, with electrons surrounding it moving in circular orbits. This model was
proposed by Niels Bohr in 1913 and after some further research, energy levels and
sublevels were recognised, and the model was refined.
Using your knowledge of atomic structure, complete Table 1.1 below for the particles
found in an atom.
Table 1.1
Particle
Relative charge
Relative mass
Proton
Neutron
Electron
(3 marks)
(b) State the block in the Periodic Table in which silicon is placed. Explain your answer.
(2 marks)
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(c) A mass spectrometer can be used to detect isotopes of an element, such as silicon. For
these to be detected in the mass spectrometer, a sample containing the isotopes must
first be vapourised and then ionised.
Give two reasons why the sample of isotopes must be ionised, and state what could be
adjusted in order to allow ions formed by different isotopes to reach the detector.
(3 marks)
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2 (a) Using your Periodic Table, complete Table 1.1
Table 1.1
Symbol
Protons
Neutrons
Electrons
23Na
32S2-
86
Sr2+
(2 marks)
(b) Sodium is an element in Period 3. State and explain the trend in atomic radius across the
period.
Trend ...........................................................................................................................................
Explanation .................................................................................................................................
(3 marks)
(c) Chlorine is an element in Period 3 which has an atomic radius of 99 pm. The chloride ion
has an ionic radius of 167 pm.
Explain the difference between the two radii.
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(3 marks)
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3 (a) The composition of atoms and ions can be determined from knowledge of atomic
number, nucleon number and charge.
Complete Table 3.1.
Table 3.1
Atomic
Nucleon
Number of
Number of
Number of
number
number
electrons
protons
neutrons
15
Symbol
31 3−
15 P
18
17
19
(2 marks)
(b) Beams of protons, neutrons and electrons behave differently in an electric field due to
their differing properties.
Fig. 3.1 shows the path of a beam of electrons in an electric field.
Add and label lines to Fig. 3.1 to represent the paths of beams of electrons and neutrons
in the same field.
Fig. 3.1
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(3 marks)
(c) Chlroine and sulfur are in Period 3. Outline why the chlorine atom has a smaller atomic
radius than the sulfur atom.
(2 marks)
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Hard Questions
1 (a) Table 4.1 below shows the atomic radii for the elements of Period 2, Li to F.
Table 4.1
Element
Li
Be
B
C
N
O
F
Atomic radius / pm
152
112
88
77
70
66
64
i) Explain the variation in atomic radius.
[4]
ii) The value for neon is missing in Table 4.1. Explain why the atomic radius of neon
cannot be measured in the same way as the other Period 2 elements.
[2]
(6 marks)
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(b) Complete Fig. 4.1 to show the electronic configuration of boron in the excited state.
Fig. 4.1
(1 mark)
(c) Explain why the first ionisation energy of boron is lower than the first ionisation of
beryllium.
(2 marks)
(d) The successive ionisation energies for another element, J, are shown in Table 4.2.
Table 4.2
Energy number
1st
2nd
3rd
4th
5th
Ionisation energy value / kJ mol−1
738
1450
7733
10543
13630
State the formula of the compound when element J reacts with chlorine.
(1 mark)
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13