Pearson Edexcel IAL Chemistry Topic 2: Atomic Structure & the Periodic Table Question Bank

Practise atomic structure, isotope notation, mass spectra and ionisation energy data using tables, spectra and particle counts.

Exam points

interpret isotope notation to find protons, neutrons and electrons in atoms or ions
draw or read mass spectra, including molecular ion peaks for diatomic molecules
use successive ionisation energy tables to deduce an element and explain jumps

Covered syllabus points

2.1—The structure of an atom in terms of electrons, protons and neutrons 2.2—The relative mass and charge of protons, neutrons and electrons 2.3—What is meant by the terms ‘atomic (proton) number’ and ‘mass number’2.4—The atomic number and the mass number to determine the number of each type of subatomic particle in an atom or ion 2.5—The term ‘isotope’2.6—The basic principles of a mass spectrometer 2.7—Predict mass spectra 2.8—Define first, second and third ionisation energies and understand that all ionisation energies are endothermic 2.9—An orbital is a region within an atom that can hold up to two electrons with opposite spins 2.10—How ionisation energies are influenced by the number of protons in the nucleus, the electron shielding and the sub-shell 2.11—Ideas about electronic structure developed from: i an understanding that successive ionisation energies provide evidence 2.12—The shapes of s and p orbitals 2.13—Orbitals in sub-shells: i each take a single electron before pairing up ii pair up with two electrons of opposite spin 2.14—Predict the electronic configuration of atoms of the elements from hydrogen to krypton inclusive and their ions 2.15—Electronic configuration determines the chemical properties of an element 2.16—The Periodic Table is divided into blocks, such as s, p and d, and know the number of electrons that can occupy s, p and d 2.17—Represent data, in a graphical form (including the use of logarithms of first ionisation energies on a graph) for elements 1 2.18—Explain: i the trends in melting and boiling temperatures of the elements of Periods 2 and 3 of the Periodic Table in terms

[Maximum number: 1]

Which statement about subatomic particles is correct?

neutral atoms always contain the same number of protons and electrons

neutral atoms always contain the same number of protons and neutrons

electrons have a relative mass of 1 and a charge of -1

protons have a relative mass of 1 and no charge

[Maximum number: 7]

This question is about copper and its compounds.

(a)

A sample of copper contains the isotopes ${ }^{63} \mathrm{Cu}$ and ${ }^{65} \mathrm{Cu}$ .

[ 7 ]

(i)

Complete the table to show the numbers of subatomic particles in the atoms of these two isotopes of copper.

Table for Question (i) — Edexcel A-Level Chemistry AS

[ 2 ]

One mark for each correct row
Four or five correct scores one mark
Ignore working

(2)

Isotope

Protons

Neutrons

Electrons

${ }^{63} \mathrm{Cu}$

29

34

29

(1)

${ }^{65} \mathrm{Cu}$

29

36

29

(ii)

Explain the term isotopes, using the information in the table.

[ 2 ]

(iii)

State why the two isotopes of copper have the same chemical reactions.

[ 1 ]

(iv)

The relative atomic mass of copper in this sample is 63.4.

Calculate the percentage abundances of the isotopes ${ }^{63} \mathrm{Cu}$ and ${ }^{65} \mathrm{Cu}$ in this sample.
You must show your working.

[ 2 ]

An explanation that makes reference to the following points:

- expression relating isotopic masses $A_{\mathrm{r}}$ and X

- abundance of (Cu) 63=0.8 or 80% abundance of (Cu) 65=0.2 or 20%

Alternative method

65-63.4=1.6

63.4-63=0.4

$0.4 / 2.0 \times 100=20 \% \quad 65$ $1.6 / 2.0 \times 100=80 \% \quad 63$

Example of calculation

$63.4=\frac{(1-\mathrm{X}) \times 65)+(\mathrm{X} \times 63)}{1}$

63.4=65-65 X+63 X

63.4=65-2 X

-1.6=-2 X

X / 63=0.8

(2)

OR

$63.4=\frac{(100-X) \times 65)+(X \times 63)}{100}$

6340=6500-65 X+63 X

6340=6500-2 X

-160=-2 X

X / 63=80 %

OR

$63.4=\frac{(100-X) \times 63)+(X \times 65)}{100}$

6340=6300-63 X+65 X

6340=6300+2 X

40=2 X

X / 65=20 %

Correct answer with or without working scores (2)

[Maximum number: 6]

This question is about magnesium, magnesium oxide and magnesium sulfate.

(a)

A sample of magnesium contains three isotopes and has a relative atomic mass of 24.32.
The table gives the relative abundances of two of these isotopes.

Table for Question (a) — Edexcel A-Level Chemistry AS

[ 6 ]

(i)

Calculate the relative abundance and hence the mass number of the third isotope.
Give your answer to the appropriate number of significant figures.
You must show all your working.

[ 4 ]

An answer that makes reference to the following points:

- calculation of the \% abundance of the third isotope

(1)

- substitute equation

(1)

- calculation of the mass of the $3^{\text {rd }}$ isotope

(1)

- answer to 2 SF only

(1)

Example of calculation

100-78.99-10.00=11.01(%)

100-78.99-10.00 = 11.01(\%)

$24.32=\frac{(24 \times 78.99)+(25 \times 10)+(y \times 11.01)}{100}$ $\mathrm{y}=\frac{2432-(24 \times 78.99)-(25 \times 10)}{11.01}$

y=25.998

(4)

(ii)

State one similarity and one difference between these isotopes.

[ 1 ]

(iii)

State which of these isotopes would be deflected most in a mass spectrometer. Justify your answer.

[ 1 ]

An answer that makes reference to the following point:

- ${ }^{24} \mathrm{Mg}$ and lowest mass or lowest m / z ratio (so deflected more by the magnetic field)

Allow ${ }^{24} \mathrm{Mg}$ is lightest Allow ${ }^{24} \mathrm{Mg}^{+}$

Ignore just the lowest mass

(1)

All question bank results loaded

Covered syllabus points

Topic 2: Atomic Structure and the Periodic Table question 1

Topic 2: Atomic Structure and the Periodic Table question 2

Question (a)

Question (i)

Question (ii)

Question (iii)

Question (iv)

Topic 2: Atomic Structure and the Periodic Table question 3

Question (a)

Question (i)

Question (ii)

Question (iii)