Topics 2 and 12: Atomic structure
IB DIPLOMA PROGRAMME CHEMISTRY SUMMATIVE TEST
HIGHER LEVEL
28th September 2021
TIME: 75 minutes
NAME:
INSTRUCTIONS TO CANDIDATES

Write your name in the box above.

In section I, write the letter of your choice in the box against the question

In section II, write your answer in the spaces provided

The number of marks is given in brackets [ ] at the end of each question or part question.

Use of calculators is allowed.

This document consists of 14 printed pages.

A clean copy of the data booklet is required for this paper.
QUESTION
MARKS
1-15
15
18
8
16
5
19
9
17
6
20
7
TOTAL
50
PERCENT
GRADE
1
FEEDBACK ON ASSESSMENT
S (my strengths are):
I (I need to improve on):
R (what will I do to improve):
2
SECTION I: Write your choice in the box against the question
2. What is the ground state electron configuration of an atom of chromium, Cr (Z = 24)?
A. [Ar]3d6
B. [Ar]4s23d4
C. [Ar]4s13d5
D. [Ar]4s24p4
3. Which describes an atom of bismuth, Bi (Z = 83)?
3
4. Which electron transition emits radiation of the longest wavelength?
5. Which is correct for the line emission spectrum for hydrogen?
A. Line M has a higher energy than line N.
B. Line N has a lower frequency than line M.
C. Line M has a longer wavelength than line N.
D. Lines converge at lower energy.
6. Which statement explains one of the decreases in first ionization energy (I.E.) across
period 3?
4
A. The nuclear charge of element Al is greater than element Mg.
B. The electron-electron repulsion is greater, for the electron with the opposite spin, in
element S than in element P.
C. A new sub-level is being filled at element S.
D. The p orbital being filled in element Al is at a lower energy than the s orbital in
element Mg.
7. Which of the following transitions in the hydrogen atom emits the most energy?
A. n = 2 to n = 1
B. n = 3 to n = 2
C. n = 4 to n = 2
D. n = 5 to n = 3
8. Bromine consists of two stable isotopes that exist in approximately a 1 : 1 ratio. The
relative atomic mass, Ar, of bromine is 79.90. Which are the stable isotopes of bromine?
A. 79Br and 81Br
B. 80Br and 81Br
C. 78Br and 80Br
D. 79Br and 80Br
5
9. Which transition in the hydrogen atom emits visible light?
A. n = 1 to n = 2
B. n = 2 to n = 3
C. n = 2 to n = 1
D. n = 3 to n = 2
10. Which of the following would have the same numerical value for all elements in the same
period?
A. Highest energy levels occupied
B. Energy sub-levels occupied
C. Orbitals occupied
D. Valence electrons
11. Which is correct for
?
6
12
13. Which is correct for
?
14. Which transition on the diagram corresponds to the ionization of hydrogen in the ground state?
7
15. Which of the following transitions in the hydrogen atom emits the least energy?
A. n = 2 to n = 1
B. n = 3 to n = 1
C. n = 4 to n = 2
D. n = 4 to n = 3
8
SECTION II: Answer all questions in the spaces provided
16. The element chromium is present in meteorites. (a) A meteorite was analysed using
mass spectrometry (MS). The mass spectrum below shows the relative abundances of
the different chromium isotopes.
a) Calculate the relative atomic mass, Ar, of chromium using information from the
spectrum above to 2 decimal places.
[3 marks]
9
b) Use the s,p,d,f notation to write the electron configuration of chromium.
[2 marks]
17. Theories are subject to change and can result in a paradigm shift. Theories explaining
the structure of the atom have suffered such shift. Bohr used line spectra to propose
the existence of fixed shells in atoms which supplanted earlier theories.
a) Distinguish between continuous and line spectra.
[2 marks]
b) Describe the appearance of the visible emission spectrum of hydrogen.
[2 marks]
c) Outline how this spectrum provides evidence for the existence of energy levels in
the hydrogen atom
[2 marks]
18. It is the nature of science to use evidence to develop theories, propose laws and
hypotheses.
The diagram below shows the first ionization energies of elements in the periodic
table.
10
i)
State what is meant by first ionization energy
[2 marks]
ii)
State and explain the trend in first ionization energies across any period
[2marks]
iii)
Explain how the graph provides evidence for the existence of the following in
atoms:
1. Shells
[2 marks]
11
2. Sub-shells(orbitals)
[2 marks]
19. a) The emission spectrum of an element can be used to identify it.
(i) Draw the first four energy levels of a hydrogen atom on the axis, labelling
n = 1, 2, 3 and 4.
[3 marks]
(ii) Draw the lines, on your diagram, that represent the electron transitions in the visible part
of the emission spectrum.
[2 marks]
b) Hydrogen spectral data give the frequency of 4.28 × 1015 s−1 for its convergence limit
in the UV region.
i)
Calculate the ionization energy, in kJmol-1, for hydrogen using sections 1
and 2 of the data booklet.
[2 marks]
12
ii)
Calculate the wavelength, in m, for the electron transition corresponding to
the frequency in (a)(iii) using section 1 of the data booklet.
[2 mark]
20. a) The electron configuration of iron is [Ar] 3dx 4sy.
Fill the boxes below to show the electron configuration of iron
[2 mark]
b) Draw the shape of a pz orbital on the axes below.
[1 marks]
c) The graph of the successive ionization energies of magnesium is shown below.
13
i)
Outline what the graph indicates about the arrangement of electrons in an atom
of magnesium.
[2 mark]
ii)
Explain the sharp increase in ionization energy values between the 10th and
11th electrons.
[2 marks]
14