as 01 ques

ATOMIC STRUCTUREAS TOPIC 1

SUBATOMIC PARTICLES

RELATIVE ATOMIC MASS

THE MASS SPECTROMETER

PRINCIPLES OF MASS SPECTROMETRY

RELATIVE ATOMIC MASS FROM MASS SPECTROMETRY

FIRST IONISATION ENERGY

CHANGES IN FIRST IONISATION ENERGIES ACROSSTHE PERIODIC TABLE

SUCCESSIVE IONISATION ENERGIES

ELECTRONIC CONFIGURATIONS OF ATOMS

ELECTRON AFFINITY

ATOMIC RADII

COMPARISIONS OF ATOMIC AND IONIC RADII

IONISING RADIATIONS

RADIOACTIVITY

APPLICATIONS OF RADIO-ISOTOPES

TEST QUESTION I

TEST QUESTION II

Questionsheet 1

Questionsheet 2

Questionsheet 3

Questionsheet 4

Questionsheet 5

Questionsheet 6

Questionsheet 7

Questionsheet 8

Questionsheet 9

Questionsheet 10

Questionsheet 11

Questionsheet 12

Questionsheet 13

Questionsheet 14

Questionsheet 15

Questionsheet 16

Questionsheet 17

QUESTIONSHEETS AS LevelCHEMISTRY

16 marks

12 marks

13 marks

15 marks

14 marks

14 marks

13 marks

16 marks

15 marks

16 marks

16 marks

18 marks

14 marks

16 marks

16 marks

19 marks

16 marks

AuthorsTrevor Birt John BrockingtonDonald E Caddy Kevin FrobisherAndrew Jones Andy Shepherd

EditorJohn Brockington

Curriculum Press – Licence Agreement:Paper copies of the A-Level Chemistry Questionsheetsmay be copied free of charge by teaching staff or studentsfor use within their school, provided the PhotocopyMasters have been purchased by their school. No part ofthese Questionsheets may be reproduced or transmitted,in any other form or by any other means, without theprior permission of the publisher. All rights are reserved.This license agreement is covered by the laws of Englandand Wales © Curriculum Press March 2000.

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TOPIC 1 Questionsheet 1

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SUBATOMIC PARTICLES

16

a) (i) Define the terms atom and element, distinguishing carefully between these two terms.

Atom ......................................................................................................................................................[1]

...................................................................................................................................................................

Element ......................................................................................................................................................

............................................................................................................................................................... [1]

(ii) Define the term isotopes.

...........................................................................................................................................................................

....................................................................................................................................................................... [2]

(iii) Define the terms mass number and atomic number. Use these terms to explain the difference betweenthe terms element and isotope.

Mass number .........................................................................................................................................[1]

Atomic number ......................................................................................................................................[1]

Difference between an element and an isotope .........................................................................................

............................................................................................................................................................... [2]

b) Name the main particles found in the atomic nuclei of all elements, with the exception of an isotope of oneparticular element. Give the main characteristics of these particles and name the exceptional isotope.

Names and characteristics ................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [4]

Exception .......................................................................................................................................................[1]

c) Using your Periodic Table, complete the following table:

Radon-222

Number of neutrons Number of electrons

208Pb2+

127I-

[3]



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12

RELATIVE ATOMIC MASS

a) (i) Define the term relative abundance as it refers to isotopes of elements in the Earth’s crust.

...........................................................................................................................................................................

....................................................................................................................................................................... [2]

(ii) Define the term relative atomic mass.

...........................................................................................................................................................................

....................................................................................................................................................................... [2]

(iii) Bromine occurs as two stable isotopes in the Earth’s crust, bromine-79 and bromine-81. The relativeabundances of these are 50.5% and 49.5% respectively. Use these data to calculate the relative atomicmass of bromine to one decimal place.

...........................................................................................................................................................................

....................................................................................................................................................................... [2]

b) (i) In quantitative chemistry, the amount of a substance is quoted as a number of moles. Define the termmole.

...........................................................................................................................................................................

....................................................................................................................................................................... [2]

(ii) Define the term molar mass and the write down a mathematical expression which relates this term tothe number of moles and mass.

Molar mass ............................................................................................................................................[1]

Relationship ..............................................................................................................................................

............................................................................................................................................................... [1]

(iii) How many particles are there in 15 grams of carbon-12 ?(Take Avogadro’s number, L, to be 6.023 x 1023)

...........................................................................................................................................................................

....................................................................................................................................................................... [2]



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13

THE MASS SPECTROMETER

[6]b) (i) What are the main functions of a vacuum pump in a mass spectrometer?

...........................................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [2]

(ii) Explain the meaning of the term mass spectrum.

...........................................................................................................................................................................

....................................................................................................................................................................... [2]

(iii) Explain why a chemical species must be positively charged to be detected by a mass spectrometer.

...........................................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [3]

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○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○

A

B

D

+

○

○

○

○

○

○

○

○

CC E

F

F

a) Label the components of the mass spectrometer, A - F.



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15

PRINCIPLES OF MASS SPECTROMETRY

Explain the terms ionisation, fragmentation, acceleration, deflection and detection as used in mass spectrometry.

Ionisation ................................................................................................................................................................

................................................................................................................................................................................

............................................................................................................................................................................ [4]

Fragmentation ........................................................................................................................................................

................................................................................................................................................................................

............................................................................................................................................................................ [4]

Acceleration ............................................................................................................................................................

................................................................................................................................................................................

............................................................................................................................................................................ [3]

Deflection ...........................................................................................................................................................[1]

Detection.................................................................................................................................................................

................................................................................................................................................................................

............................................................................................................................................................................ [3]



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14

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RELATIVE ATOMIC MASS FROM MASS SPECTROMETRY

a) The mass spectrum of a sample of gallium contains only two peaks at mass/charge ratios 69 and 71.The heights of these peaks in a mass spectrum of gallium are 145 mm and 95 mm.(i) Calculate the relative abundance of each isotope of gallium to one decimal place.

...........................................................................................................................................................................

....................................................................................................................................................................... [2]

(ii) Calculate the relative atomic mass of gallium to two decimal places.

...........................................................................................................................................................................

....................................................................................................................................................................... [2]

(iii) Why is it a good approximation to assume that the relative mass of the Ga+ cations, calculated from massspectrometry, is the same as the relative atomic mass of Ga?

....................................................................................................................................................................... [2]

b) The diagram below is the mass spectrum for molecular bromine.

(i) Identify the chemical species responsible for each peak in the spectrum.

...........................................................................................................................................................................

....................................................................................................................................................................... [4]

(ii) Bromine occurs in the Earth’s crust as two stable isotopes with approximately 50% relative abundance.Why are the peaks corresponding to mass/charge ratios of 79 and 81 of similar height?

...........................................................................................................................................................................

....................................................................................................................................................................... [2]

(iii) Explain why the heights of the triplet of peaks at mass/charge ratio 158, 160 and 162 are in the ratio1 : 2: 1.

...........................................................................................................................................................................

....................................................................................................................................................................... [2]

100

50

070 80 90 150 160 170

∫∫Mass / Charge Ratio

Rel

ativ

e A

bund

ance

/ %



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14

FIRST IONISATION ENERGY

a) Define the term first ionisation energy and write an equation to represent the first ionisation energy of chlorine.

Definition ..........................................................................................................................................................

...........................................................................................................................................................................

...................................................................................................................................................................... [4]

Equation........................................................................................................................................................ [2]

b) Give the name of the enthalpy change occurring in the following process:-Mn3+(g) → Mn4+(g) + e-

....................................................................................................................................................................... [1]

c) State whether the process in b) is exothermic or endothermic and explain your choice.

...........................................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [3]

d) State and explain the trend in first ionisation energies down a group of the Periodic Table.

...........................................................................................................................................................................

...........................................................................................................................................................................

...........................................................................................................................................................................

...........................................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [4]



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CHANGES IN FIRST IONISATION ENERGIES ACROSS THE PERIODIC TABLE

13

a) State and explain the general trend in first ionisation energies across a period of s-block and p-block elements.

...........................................................................................................................................................................

...........................................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [3]

b) Statement 1“Between Groups 2 and 3 and between Groups 5 and 6 this overall trend is contravened.”(i) Using ‘electron-in-box’ notation, draw the electron configurations of beryllium and boron and, also, the

configurations of the chemical species which are formed when the first ionisation occurs.

[2](ii) Using ‘electron-in-box’ notation, draw the electron configurations of nitrogen and oxygen and, also,

the configurations of the chemical species formed when the first ionisation occurs.

[2](iii) Using the diagrams you have given, explain Statement 1.

...........................................................................................................................................................................

...........................................................................................................................................................................

...........................................................................................................................................................................

...........................................................................................................................................................................

...........................................................................................................................................................................

...........................................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [6]



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SUCCESSIVE IONISATION ENERGIES

16

Consider the first eight successive ionisation energies for three elements.

a) Suggest to which group in the Periodic Table each element belongs. Give the reasons for your choice.

...........................................................................................................................................................................

...........................................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [5]

b) Place the atoms in order of increasing atomic number.

....................................................................................................................................................................... [2]

c) X is from the third period. Suggest its identity and use the data to sketch the shape of a graph of logarithm(successive ionisation energy) versus number of electrons removed.

Identity of X ...................................................................................................................................................[1]

7th

21700

23400

12300

2nd

1450

1820

1150

Element Successive ionisation energies / kJ mol-1

1st

736

577

590

3rd

7740

2740

4940

4th

10500

11600

6480

5th

13600

14800

8120

6th

18000

18400

10700

8th

25600

27500

14600

X

Y

Z

[3]

d) On your graph indicate from which sub-shell each electron is removed. [2]

e) Explain what could be deduced about the electronic energy levels in a sodium atom from inspection of the 11successive ionisation energies of this element.

...........................................................................................................................................................................

...........................................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [3]

1 2 3 4 5 6 7 8

No. of electrons removed →

↑lg I



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ELECTRONIC CONFIGURATIONS OF ATOMS

15

a) Information is summarised for the s-block element, sodium, in the following table. Complete the table for theother species.

b) With the aid of labelled diagrams, describe the three dimensional shape of the following atomic orbitals:(i) an s atomic orbital

Description ........................................................................................................................................................Diagram

[2]

(ii) a py atomic orbital

Description ........................................................................................................................................................Diagram

[2]

c) Place the following orbitals in ascending order of energy, starting with a 1s orbital.1s, 3p, 5d, 4s, 4f, 6p, 4p, 5s, 2p, 3d.

...........................................................................................................................................................................

....................................................................................................................................................................... [3]

d) Explain why the first row of d-block elements is placed in the fourth row of the Periodic Table, when,generally, their electronic configurations change by the addition of electrons to the third shell.

...........................................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [2]

Element/Ion Electronic configuration Block

Sodium 1s2 2s2 2p6 3s1 s

Copper

Silicon

Sulphide, S2-

[6]



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ELECTRON AFFINITY

16

a) (i) Explain the meaning of the term first electron affinity with reference to oxygen.

...........................................................................................................................................................................

....................................................................................................................................................................... [2]

(ii) Write an equation for the process by which second electron affinity of oxygen is defined.

....................................................................................................................................................................... [2]

(iii) State whether the first and second electron affinities of oxygen are exothermic or endothermic or neither.Explain your statement.

First electron affinity ................................................................................................................................

............................................................................................................................................................... [2]

Second electron affinity .............................................................................................................................

............................................................................................................................................................... [2]

b) (i) Suggest how and why the values of the electron affinities down Group 7 in the Periodic Table vary fromchlorine to iodine.

...........................................................................................................................................................................

....................................................................................................................................................................... [2]

(ii) Predict, giving your reasons, whether the first electron affinity of sulphur is greater or smaller than thefirst electron affinity of chlorine.

...........................................................................................................................................................................

...........................................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [3]

(iii) The electron affinity of fluorine is said to be ‘anomalous’ when compared with the rest of the Group 7elements. What does this statement mean and why is it so?

...........................................................................................................................................................................

...........................................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [3]



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ATOMIC RADII

16

a) Explain what is meant by the terms atomic shielding, nuclear charge and effective nuclear charge.

Atomic shielding ................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [3]

Nuclear charge ..................................................................................................................................................

....................................................................................................................................................................... [2]

Effective nuclear charge ....................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [2]

b) Use these terms to explain the following trends.(i) Variation of atomic radii across a period of s- and p-block elements in the Periodic Table.

...........................................................................................................................................................................

...........................................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [3]

(ii) Variation of atomic radii down a group of elements in the Periodic Table.

...........................................................................................................................................................................

...........................................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [3]

(iii) Variation of atomic radii across a row of d-block elements in the Periodic Table.

...........................................................................................................................................................................

...........................................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [3]



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COMPARISONS OF ATOMIC AND IONIC RADII

18

For each of the following pairs of chemical species, state which has the larger radius. Explain your choice.

a) Na and Cl ...........................................................................................................................................................

...........................................................................................................................................................................

...................................................................................................................................................................... [3]

b) Na+ and Rb+ ......................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [3]

c) Cu+ and Cu2+ ......................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [3]

d) Cl and Cl-...........................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [3]

e) H+ and H- ..........................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [3]

f) O- and O2- ..........................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [3]



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IONISING RADIATIONS

14

a) (i) Complete the following table

Radiation Nature of radiation Relative penetrative power

Alpha Thin sheet of paper

Emission of electrons

Gamma[5]

(ii) Using a labelled sketch, describe how each of these forms of radiation is affected by an electrical fieldcreated between two electrodes.

[5]

b) (i) Suggest why the occurrence of lung cancer can be higher than the national average in some communitiesliving in stone houses, and name the element concerned.

...........................................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [2]

(ii) The particular isotopes concerned are alpha emitters, which have very limited penetrating power. Explainwhy they cause lung cancer, especially.

...........................................................................................................................................................................

....................................................................................................................................................................... [2]



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RADIOACTIVITY

16

a) (i) What is meant by the term radio-isotope?

....................................................................................................................................................................... [1]

(ii) Define the term half-life of a radionuclide.

....................................................................................................................................................................... [1]

(iii) Write a balanced equation for the decay of thorium-228 by emission of alpha radiation.

....................................................................................................................................................................... [2]

(iv) Write a balanced equation for the decay of radium-228 by emission of beta radiation.

....................................................................................................................................................................... [2]

(v) Thorium-232 can decay to thorium-228 in three steps. Suggest a possible route, giving a balancednuclear equation for each step.

...........................................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [4]

b) (i) Radon-222 is radioactive but almost chemically inactive. Explain this statement.

...........................................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [2]

(ii) Radon-222 undergoes alpha emission with a half-life of 3 days and 20 hours. What percentage of asample of radon-222 will remain after 19 days and 4 hours ?

...........................................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [2]

(iii) The half-life of radon-220 is 52 seconds. Approximately, how long will it take to decay to 6.25% of itsoriginal mass ?

...........................................................................................................................................................................

....................................................................................................................................................................... [2]



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APPLICATIONS OF RADIO-ISOTOPES

16

a) Carbon from a sample of an ancient relic from an archaeological investigation gave a reading on a radiationcounter of 7.5 counts per minute. Fresh wood gave a reading of 15 counts per minute. How long ago wouldyou deduce the sample was made ? Give any assumptions you would make.

Age of sample ....................................................................................................................................................

....................................................................................................................................................................... [2]

Assumptions .......................................................................................................................................................

....................................................................................................................................................................... [2]

b) Name a radio-isotope which is used in medicine and briefly outline its application.

...........................................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [3]

c) (i) Explain, using a sketch, how a radioactive source can be used to control the thickness of the sheet steelfrom a rolling mill.

Sketch

Explanation ...............................................................................................................................................

...................................................................................................................................................................

...................................................................................................................................................................

............................................................................................................................................................... [4]

(ii) What properties of a radio-isotope would you consider in selecting the best radio-isotope for this function?Explain your choice.

...........................................................................................................................................................................

...........................................................................................................................................................................

...........................................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [5]



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a) (i) State and explain what would happen if a beam of protons, neutrons and electrons were to be passedbetween two metal plates, one positively charged and the other negatively charged.

ProtonsEffect..................................................................................................................................................... [1]

Explanation........................................................................................................................................... [1]

NeutronsEffect..................................................................................................................................................... [1]

Explanation........................................................................................................................................... [1]

ElectronsEffect..................................................................................................................................................... [1]

Explanation........................................................................................................................................... [1]

(ii) One of the particles mentioned in a) (i) would be deflected considerably more than the others. Whichone, and why?

...........................................................................................................................................................................

....................................................................................................................................................................... [2]

b) Naturally occurring sulphur contains 95.0% sulphur-32, 0.76% sulphur-33 and 4.2% sulphur-34.

(i) Complete the following table.

Number of protons Number of neutrons Number of electrons

Sulphur-32 16

Sulphur-33

Sulphur-34[3]

(ii) Write down the symbols of these three isotopes, taking care that the atomic number and mass number ofeach are shown in their correct positions.

....................................................................................................................................................................... [3]

(iii) Which of these three isotopes of sulphur would you expect to have the:

highest first ionisation energy?............................................................................................................. [1]

highest melting point?........................................................................................................................... [1]

greatest chemical reactivity?................................................................................................................ [1]

(iv) Use the data in b) (i) to calculate the relative atomic mass of sulphur.

...........................................................................................................................................................................

....................................................................................................................................................................... [2]

TEST QUESTION I

19



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a) Element X has an atomic number of 9. Figure 1 shows its mass spectrum and Figure 2 is a graph of itssuccessive lg ionisation energies.

TEST QUESTION II

(i) Write down the electronic configuration of the element X.

....................................................................................................................................................................... [1]

(ii) To which group of the Periodic Table does X belong?

....................................................................................................................................................................... [1]

(iii) What is the relative atomic mass of X?

....................................................................................................................................................................... [1]

(iv) In what way is the isotopic composition of X unusual?

....................................................................................................................................................................... [1]

(v) Write down the formulae of the species which account for the two peaks shown in Figure 1.

....................................................................................................................................................................... [2]

(vi) How do you account for the shape of the graph shown in Figure 2?

...........................................................................................................................................................................

...........................................................................................................................................................................

....................................................................................................................................................................... [3]

(Continued...)

1 2 3 4 5 6 7 8 9

No. of electrons removed

lg I

Figure 2Figure 1

19 38

Mass/charge ratio

Rel

ativ

e ab

unda

nce



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TEST QUESTION II

TOPIC 1 Questionsheet 17 Continued

b) Element Y has the electronic configuration 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p1.

(i) To which group of the Periodic Table does Y belong?

....................................................................................................................................................................... [1]

(ii) Y has a relative atomic mass of 69.7, and consists of a mixture of two isotopes of mass numbers 69 and71 respectively. On the axes of Figure 3, sketch the mass spectrum you would expect for element Y.

[2]

16

Figure 3

Mass/charge ratio

Rel

ativ

e ab

unda

nce

0 10 20 30No. of electrons removed

Lg I

Figure 4

(iii) On the axes of Figure 4, sketch the graph you would expect for successive lg ionisation energies ofelement Y.

[3]

c) Write down the likely formula of a compound which could be formed between X and Y.

....................................................................................................................................................................... [1]