1. NT Exampro 1
1. (a) Complete the following table.
Atom Number of
protons
Number of
neutrons
Number of
electrons
Ir
Mo
191
77
96
42
(2)
(b) The element gallium consists of two types of atom of relative mass 69.0 and 71.0
respectively. The percentage abundance of the atoms of relative mass 69.0 is 60.2.
(i) Calculate the relative atomic mass of gallium.
(ii) What name is given to these different atoms of gallium?
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(2)
(c) Define the term second ionisation energy. Write an equation, using the element
potassium, to show this change.
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(3)
(d) The first seven ionisation energies (kJ mol–1) for two elements A and B in the same Period
of the Periodic Table are:
Element
A
B
1
1012
578
2
1903
1817
3
2912
2745
4
4957
11578
5
6274
14831
6
21269
18378
7
25398
23296
(i) Explain the relative magnitude of the first and second ionisation energies of
element B.
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2. NT Exampro 2
(ii) Explain the relative magnitude of the first ionisation energy for elements A and B.
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(4)
(Total 11 marks)
2. Complete the following table.
Atom Number of
protons
Number of
neutrons
Number of
electrons
Ir
Mo
191
77
96
42
(2)
3. The element gallium consists of two types of atom of relative mass 69.0 and 71.0 respectively.
The percentage abundance of the atoms of relative mass 69.0 is 60.2.
(i) Calculate the relative atomic mass of gallium.
(ii) What name is given to these different atoms of gallium?
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(2)
4. Define the term isotope.
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(1)
5. From the position of radium in the Periodic Table, predict the following:
(a) the formula of radium carbonate;
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3. NT Exampro 3
(b) the equation for the thermal decomposition of solid radium carbonate;
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(c) how the decomposition temperature required in (d)(ii) would compare with that required
for magnesium carbonate.
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(Total 4 marks)
6. (a) Define the terms
(i) atomic number;
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(1)
(ii) mass number;
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(1)
(iii) relative atomic mass.
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(1)
(b) In 1919 F. W. Aston, using an early form of the mass spectrometer, showed that neon
exists as a mixture of isotopes.
The mass spectrum is shown below; determine the relative atomic mass of neon.
100
80
60
40
20
18 20 22 24
relative
abundance
m/e
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....................................................................................................................................
(2)
(c) (i) Define the second ionisation energy of fluorine.
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4. NT Exampro 4
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..........................................................................................................................
(2)
(ii) Sketch a graph on the axes below to show the successive ionisation energies of
fluorine. Give reasons for the shape of the line you draw.
log
ionisation
energy
number of ionisation
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(4)
(Total 11 marks)
7. Define the terms
(a) atomic number;
...........………..............................................................................................................
(1)
(b) mass number;
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(1)
(c) relative atomic mass.
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(1)
(Total 3 marks)
8. (i) Give the electronic configuration of an atom of the isotope of calcium, 20
45
Ca.
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5. NT Exampro 5
(1)
(ii) Give the names and numbers of each type of particle present in a nucleus of this isotope.
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(2)
(iii) State one reason why the information in (i) is usually more useful to chemists than
that in (ii).
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(1)
(Total 4 marks)
9. The species X, Y and Z are atoms or ions.
species X Y Z
atomic number 16 16 16
mass number 32 35 32
net charge 0 0 –2
(a) (i) State the number of electrons, protons and neutrons X
electrons .......................... protons ......................... neutrons .......................
(1)
(ii) What is the relationship between X and Y?
……………………………………………………………………………..…
(1)
(iii) Identify Z
……………………………………………………………………………..…
(1)
(b) 332 kJ of energy are required to convert a mole of gaseous atoms of X to a mole of
gaseous Z
(i) Represent by equations the two steps which make up this energy change.
……………………………………………………………………………..…
……………………………………………………………………………..…
(2)
(ii) Explain why the second step is endothermic
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(1)
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6. NT Exampro 6
(c) Y is radioactive, decaying by beta (β) emission.
When a sample of the product form the β decay of Y was passed into a mass spectrometer
it produced only one peak, at m/e = 35 whereas a naturally occurring sample of this
element gave an extra peak at m/e = 37.
Account for this difference between the sample of the element made from Y and the
naturally occurring sample of the same element.
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(2)
(Total 8 marks)
10. (a) (i) Define the terms:
atomic number ...............................................................................................
......................................................................................................................
mass number .................................................................................................
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(2)
(ii) Identify the particle which contains 11 protons, 12 neutrons and 10 electrons.
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(1)
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7. NT Exampro 7
(b) Bromine consists of two isotopes, mass numbers 79 and 81. A sample of bromine gas,
Br2, was examined in a mass spectrometer. The mass spectrum showing the molecular
ions is given below.
100
50
Relative
intensity
158 160 162
m/e
(i) Identify the species responsible for the peak at m/e = 160.
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(1)
(ii) Deduce the relative abundances of the two isotopes,
(2)
(c) Define the term first electron affinity for bromine atoms, illustrating your answer with an
equation.
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................................................................................................................................
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(3)
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8. NT Exampro 8
(d) The graph showing the variation of the first ionisation energies of the elements neon to
potassium is given below.
2500
2000
1500
1000
500
0
First
ionisation
energy/kJ mol–1
Ne Na Mg Al Si P S Cl Ar K
(i) Define the term first ionisation energy with reference to neon.
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(2)
(ii) Explain the general trend in the first ionisation energies of the elements sodium to
argon.
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(2)
(iii) Explain why the first ionisation energy of neon is greater than the first ionisation
energy of argon.
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(2)
(Total 15 marks)
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9. NT Exampro 9
11. (a) Iron has several isotopes. One of them has the electronic configuration [Ar]3d64s2 , an
atomic number of 26 and a mass number of 56.
(i) Which of these pieces of information would be the most use in helping a chemist
decide on the likely chemical reactions of iron?
............................................................................................................................
............................................................................................................................
(1)
(ii) State how many of each of the following particles is found in an atom of 56Fe.
Protons ................ electrons ................ neutrons ................
(2)
(iii) What are isotopes?
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(2)
(b) The relative atomic mass of a sample of iron may be found by using a mass spectrometer
to determine the isotopic composition.
(i) The diagram below represents a low-resolution mass spectrometer in which four
areas have been identified. State what happens in each of these areas.
(+)
Sample
B
CA
D
To vacuum pump
Area A ..............................................................................................................
Area B ..............................................................................................................
Area C ..............................................................................................................
Area D ..............................................................................................................
(4)
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10. NT Exampro 10
(ii) In such a determination the following isotopic composition was found.
Isotope Percentage composition
54Fe 5.8
56Fe 91.6
57Fe 2.2
58Fe 0.33
Calculate the relative atomic mass of this sample of iron, giving your answer to two
decimal places.
(2)
(Total 11 marks)
12. (a) (i) Complete the electronic configuration of a sulphur atom.
1s2...................................................................................................................
(1)
(ii) Deduce the number of neutrons in the nucleus of an atom of 32S.
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(1)
(b) (i) Define the term first electron affinity.
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(3)
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11. NT Exampro 11
(ii) The following equation represents the change occurring when the second electron
affinity of sulphur is measured.
S–(g) +e–→ S2– (g)
Explain why the second electron affinity of an element is endothermic.
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(2)
(Total 7 marks)
13. (a) (i) What is meant by the mass number of an atom?
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(1)
(ii) Define the term relative atomic mass.
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(2)
(iii) What are isotopes?
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(2)
(b) Magnesium has three isotopes. The mass spectrum of magnesium shows peaks at m/e 24
(78.60%), 25 (10.11%), and 26 (11.29%). Calculate the relative atomic mass of
magnesium to 4 significant figures.
(2)
(Total 7 marks)
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12. NT Exampro 12
14. (a) Complete the following table:
Particle Relative charge Relative mass
Proton 1
Electron –1
Neutron 1
(3)
(b) State the number of each of the above particles present in one molecule of CH4, showing
clearly how you arrive at your answer.
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(3)
(c) Complete the electronic configuration of a chlorine atom.
1s2 ............................................................................................................................
(1)
(d) Give the formula of the chlorine species composed of 17 protons, 20 neutrons and 16
electrons.
....................................................................................................................................
(2)
(e) Write one equation in each case to represent the change occurring when the following
quantities are measured.
(i) The first electron affinity of sulphur.
............................................................................................................................
(2)
(ii) The first ionisation energy of sulphur.
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(1)
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13. NT Exampro 13
(f) Explain why the first ionisation energy of chlorine is higher than that of sulphur.
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(2)
(Total 14 marks)
15. (a) (i) Write the equation for the reaction of lithium with water.
………………………………………………………………………………..
(2)
(ii) Describe what you would expect to see during the reaction.
………………………………………………………………………………..
………………………………………………………………………………..
(2)
(b) State the number of protons, neutrons and electrons in a +Li
3
7
ion.
protons: ……………… neutrons: ……………… electrons: ………………
(3)
(c) The mass spectrum of lithium shows two peaks. Their mass/charge ratios and
percentage abundance are shown below.
Mass/charge % Abundance
6.02 7.39
7.02 92.61
Calculate the relative atomic mass of lithium, giving your answer to three
significant figures.
(2)
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14. NT Exampro 14
(d) Describe a test that you would do to distinguish between solid lithium chloride and
solid sodium chloride. Clearly state what you would do and what you would see with both
substances.
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………….…………………………………………………………………………….
(3)
(Total 12 marks)
16. (a) State the meaning of the terms
(i) relative atomic mass
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..........................................................................................................................
(2)
(ii) mass number
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..........................................................................................................................
(1)
(iii) isotopes
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(2)
(b) The isotopic composition of a sample of sulphur is found using a mass spectrometer.
(i) Explain how atoms of the sample of sulphur are ionised.
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..........................................................................................................................
(2)
(ii) State the type of charge on the sulphur ions formed in the mass spectrometer.
..........................................................................................................................
(1)
(iii) State how the resulting sulphur ions are then accelerated.
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15. NT Exampro 15
..........................................................................................................................
(1)
(c) For a particular sample of sulphur atoms the following isotopic composition was recorded.
Isotope Percentage composition
32S 95.00
33S 0.76
34S 4.24
Calculate the relative atomic mass of this sample of sulphur. Give your answer to two
decimal places.
(2)
(d) Predict the electronic configuration of a 34S atom, using s, p and d notation.
1s2 .........................................................................................................................
(1)
(Total 12 marks)
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