Syllabus Edition

First teaching 2023

First exams 2025

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Electronic Configurations (HL IB Chemistry)

Exam Questions

3 hours53 questions
1a1 mark

Describe what is meant by the term orbital.

1b2 marks

Draw the shapes of the s, px, py and pz orbitals.

1c
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1 mark

State the maximum number of electrons in the n = 4 energy level.

1d2 marks

List the d, f, p and s orbitals in order of decreasing energies.

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2a2 marks

Write the full electronic configurations for the following species 

i)
K
[1]
 
ii)
Sr2+ 
[1]
2b2 marks

Write the condensed electronic configurations for the following species

i)
Na
[1]

 

ii)
Al3+ 
[1]
2c2 marks

Complete the orbital diagrams of phosphorus and fluorine as shown in the diagram below.

2-1-ib-sl-sq-easy-q4c

2d2 marks

Give the number of each type of orbital in the first four energy levels.

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3a3 marks

Using sections 1 and 5 of the data booklet describe how the following change in moving from the infrared region of the electromagnetic spectrum to the radio region of the electromagnetic spectrum.

i)
Wavelength
[1]
 
ii)
Frequency
[1]
 
iii)
Energy
[1]

3b3 marks

Describe the process occurring in an atom to produce a single line on an emission spectrum.

3c2 marks

Distinguish between a continuous spectrum and a line spectrum.

3d3 marks
Describe the emission spectrum of hydrogen. Outline how this spectrum is related to the energy levels in the hydrogen atom.

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4a1 mark

An element Y has the following first six ionisation energies in kJ mol-1. These are shown in the table below.

 

1st 

2nd

3rd

4th

5th

6th

Ionisation energy (kJ mol-1)

577

1820

2740

11600

14800

18400

State what group of the Periodic Table this element belongs to.

4b1 mark

State what can be determined from the frequency of the convergence limit in a hydrogen emission spectrum.

4c
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1 mark

Hydrogen spectral data give the frequency of 3.30 x 1015  Hz for its convergence limit.

Calculate the ionisation energy, in J, for a single atom of hydrogen using Sections 1 and 2 of the Data Booklet.

4d
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1 mark

Calculate the wavelength, in m, for the electron transition corresponding to the frequency in part (c) using Section 1 of the Data Booklet.

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5a1 mark
State which element in Period 2 will have the highest first ionisation energy value.
5b1 mark

Write an equation, including state symbols, for the third ionisation energy of beryllium.

5c1 mark

The successive ionisation energies of an element, X, are shown below.

tdJL_HNg_successive-ionisation-energies
 

State how many shells element X has.

5d1 mark

Deduce which group element X is in.

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6a1 mark

State the general trend in first ionisation energies across Period 3.

6b2 marks

The first ionisation energy of aluminium is lower than magnesium. Write the full electron configurations of aluminium and magnesium.

6c2 marks

Using the electron configurations from part (b), explain why the first ionisation energy of aluminium is lower than magnesium.

6d1 mark

Write the equation, including state symbols, for the second ionisation energy of aluminium.

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1a2 marks

The element chromium has several naturally occurring isotopes whose abundances are shown in Table 1.

Table 1

Mass number

% abundance

50

4.345

52

83.789

53

9.501

54

2.365

 

Calculate the relative atomic mass of chromium to two decimal places.

1b1 mark

State the full electron configuration for chromium.

1c2 marks

State the meaning of [Ar] and complete the orbital diagram shown below for chromium.

Figure 1

2-1-ib-chemistry-sq-q3c-medium

1d2 marks

This question is about the chromium(III) ion, Cr presubscript 24 presuperscript 52 superscript 3 plus end superscript.

i)
State the number of protons, electrons, and neutrons in the chromium(III) ion. 
[1]
 
ii)
Write the full electron configuration for the chromium(III) ion. 
[1]

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2a6 marks

This question is about line emission spectra of elements.

i)
Explain the difference between a continuous spectrum and a line spectrum. 
[2]
 
ii)
Draw a labelled diagram that shows electron transitions in a hydrogen atom in the ultraviolet and visible regions of the electromagnetic spectrum. Include three  electron transitions for each region. 
[4]
2b2 marks

The visible line emission spectrum of hydrogen is shown below in Figure 1 and the wavelengths of the first four lines are listed in Table 1.

i)
Use the information provided and Sections 1 and 2 of the IB data booklet to determine the frequency of the red line.
[1]

Figure 12-1-ib-chemistry-sq-q4b-medium

The visible line emission spectrum hydrogen

 Table 1

Balmer spectral line

Wavelength in nm

Colour

656

Red

486

Blue(cyan)

434

Blue

410

Violet

 

ii)
Which spectral line carries more energy, Hα or Hδ?
[1]
2c1 mark

Draw the shape of a 1s atomic orbital and 2p atomic orbital.    

2d2 marks

Describe the relationship between colour, energy, frequency, and wavelength in the visible spectrum.

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3a3 marks

Electron configurations give you a summary of where you can find an electron around the nucleus of an atom. They can also be determined for an ion after an atom loses or gains electrons.

i)
State the full electron configuration of the rubidium ion, Rb presubscript 37 presuperscript 85 superscript plus. 
[1]
 
ii)
State and explain the relative size of a rubidium ion compared to a krypton atom. 
[2]

3b2 marks

The element rubidium has two naturally occurring isotopes of 85Rb and 87Rb. The relative atomic mass of rubidium is 85.47. Calculate the percentage abundance of each isotope.

3c2 marks

The electrons in an atom are found in orbitals around the nucleus, which have different energy levels sometimes called shells.

i)
The fourth shell consists of the atomic orbitals 4d, 4f, 4p and 4s. List these orbitals in order of increasing energy. 
[1]
 
ii)
State the number of atomic orbitals present in 4d, 4f, 4p and 4s. 
[1]

 

3d1 mark

Rubidium forms an ionic compound with selenium, Rb2Se.

Using boxes to represent orbitals and arrows to represent electrons, sketch the orbital diagram of the selenium atom's valence shell in Figure 1.

Figure 1

2-1-ib-chemistry-sq-q5d-medium

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4a2 marks

The successive ionisation energies of an element, X, are shown below. The vertical axis plots log (ionisation energy) instead of ionisation energy to represent the data without an unreasonably long vertical axis.

q1_12-1_electrons-in-atoms-sq-medium_ib_hl

Identify element X and give its full electron configuration.

4b3 marks
Explain how the successive ionisation energy data for the element X are related to its electron configuration.

4c2 marks
Explain why the first ionisation energy of aluminium is lower than the first ionisation energy of magnesium.

4d2 marks
Explain why the first ionisation energy of sulfur is lower than the first ionisation energy of phosphorus.

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5a2 marks

The successive ionisation energies of vanadium are shown.

q2a_12-1_electrons-in-atoms-sq-medium_ib_hl


State the sub-levels from which each of the first four electrons are lost

5b2 marks
Outline why there is an increase in ionisation energy from electron 3 to electron 5.
5c3 marks
Explain why there is a large increase in the ionisation energy between electrons 5 and 6.
5d2 marks

The first six ionisation energies, in kJ mol-1, of an element are shown below.

IE1

IE2

IE3

IE4

IE5

IE6

578

1816

2744

11576

14829

18375

Explain the large increase in ionisation energy from IE3 to IE4

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6a2 marks

Emission spectra provide experimental evidence for the existence of atomic energy levels.

i)
Explain the convergence of lines in a hydrogen emission spectrum.
[1]
ii)
State what can be determined from the frequency of the convergence limit.
[1]

6b2 marks
Determine the energy, in J, of a photon of red light, correct to two significant figures, given that the wavelength is 650.0 nm using Sections 1 and 2 of the Data Booklet.
6c3 marks
Calculate the first ionisation energy, in kJ mol to the power of negative 1 end exponent, for hydrogen given that its shortest wavelength in the Lyman series is 91.16 nm using Sections 1 and 2 of the Data Booklet.
6d3 marks
Describe why the energy required to reach the convergence limit on an emission spectrum is considered the ionisation energy for an atom. You should refer to the appearance of the spectrum, frequency, and energy in your answer.

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7a3 marks

The first ionisation energies of the elements in period 3 are shown below.

q4a_12-1_electrons-in-atoms-sq-medium_hb_hl

Explain the general trend seen in ionisation energy across period 3.

7b2 marks

On the diagram below, sketch the line for the first ionisation energies of period 2 elements

q4b_12-1_electrons-in-atoms-sq-medium_ib_hl

7c5 marks

Sketch a graph of ionisation energy versus the number of electrons removed for five ionisations of silicon. Explain the shape of the trend you have drawn.

q4c_12-1_electrons-in-atoms_ib_hl-medium

7d2 marks
The wavelength of a line in the Balmer series of hydrogen is 726.2 m. Calculate the energy of photons emitted, in kJ, using Sections 1 and 2 of the Data Booklet.

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8a2 marks

The first ionisation energies of the elements in period 3 are shown.

q5a_12-1_electrons-in-atoms-sq-medium_ib_hl

Draw a graph on the diagram to show the second ionisation energies of the period 3 elements

8b3 marks
Explain the differences seen in first and second ionisation energies of the elements in period 3.
8c2 marks

Hydrogen spectral data give the frequency of 3.28 x 1015  s-1 for its convergence limit.

i)
Calculate the ionisation energy, in J, for a single atom of hydrogen using Sections 1 and 2 of the Data Booklet.
[1]
ii)
Calculate the wavelength, in nm, for the electron transition corresponding to the frequency in part (i) using Section 1 of the Data Booklet.
[1]
8d2 marks
On the diagram below, draw a line that corresponds to the first ionisation energy of hydrogen and explain your reasoning.

q5d_12-1_electrons-in-atoms-sq-medium_ib_hl

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1a1 mark

The diagram below shows electron transitions in a hydrogen atom in two regions of the electromagnetic spectrum.

hydrogen-emission-spectrum

Using section 5 of the Data booklet, predict which electron transition is most likely to correspond to the emission of red light.

1b1 mark

Using sections 1 and 5 of the data booklet, predict which electron transition will correspond to the greatest frequency of light emitted.

1c
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1 mark

The wavelengths of the first four lines for the Balmer series are shown below.

Balmer spectral line Wavelength in nm Colour
Hα 656 red
Hβ 486 cyan(blue)
Hγ 434 blue
Hδ 410 violet

Using section 1 of the Data booklet, determine the ratio of the frequencies Hα to Hγ to 2 decimal places.

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2a4 marks

Successive ionisation energies provide evidence for the arrangement of electrons in atoms. In the table below the successive ionisation energies of oxygen are given.

Ionisation number

1

2

3

4

5

6

7

8

Ionisation energy (kJ mol-1)

1314

3388

5301

7469

10989

13327

71337

84080

i)
Give the equation, including state symbols for the third ionisation energy of oxygen. 

[2]

ii)
Explain how this data shows evidence of two energy shells in oxygen.

[2]

2b3 marks

Amorphous(unorganized solid form) boron is used as a rocket fuel igniter and in pyrotechnic flares.

i)
Write an equation, including state symbols to show the process that occurs for first ionisation of boron, B. 

[1]

ii)
Suggest why the ionisation energy of boron is lower than that of beryllium going against the general trend in ionisation energies across the period.

[2]

2c
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2 marks

Using the table in part (a) and sections 1 and 2 of the data booklet, calculate the wavelength, in nm, of the convergence limit in the spectral lines of an oxygen atom.

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3a2 marks

Aluminium has 13 successive ionisation energies.

On the figure below, add crosses to show the 13 successive ionisation energies of aluminium. The value for the first ionisation energy is already completed.

You do not have to join the crosses.

St2ZbkBb_successive-ionisation-graph

3b1 mark

This question is about ionisation energies of an element, X.

The figure below represents the log of the first ten successive ionisation energies of X plotted against the number of electrons removed.

ionisation-graphState the group of the periodic table where element X is found.

3c5 marks

Element A has the following first six ionisation energies in kJ mol-1.

577, 1820, 2740, 11 600, 14 800, 18 400

i)
Explain how you know that element A is in group 3 of the periodic table.

[1]

ii)
Two elements B and C are in the same period as A, but B is in the group before A and C is in the group after A in the periodic table.
Give approximate first ionisation energies for elements B and C.

[2]

iii)
Explain, using ideas of electronic structure, the difference in ionisation energy values of element A compared to elements B and C.

[2]

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4a4 marks

The first ionisation energies of the elements H to K are shown below in the figure below

first-ionisation-energy-graph

State and explain the trend in first ionisation energies shown by the elements with the atomic numbers 2, 10 and 18

4b1 mark

Compound J reacts with chlorine. The first five successive ionisation energies for an element J, are shown in the table below.

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.

4c2 marks

The figure below shows the successive ionisation energies for a period 2 element.

graph2

With reference to electronic structures, state the identity of this element and explain your answer.

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5a5 marks

Electrons in atoms occupy orbitals. The figure below shows the first ionisation energies for six consecutive elements labelled AF in kJ mol-1

ionisation-graph-2

i)
Complete the graph of the first ionisation energies for the next five elements.
[3]
ii)
Explain why the value of the first ionisation energy for D is greater than for C.

[2]

5b4 marks

The sequence of the first three elements in the Periodic Table is hydrogen, helium and then lithium.

Explain why the first ionisation energy of hydrogen is less than that of helium but greater than that of lithium.

5c
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1 mark

Using the figure in part (a) and sections 1, 2 and 3 of the data booklet, calculate the frequency, in THz, of the convergence limit of a single atom of element C.

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6a3 marks

The table below shows the successive ionisation energies of an unknown element, X

Ionisation number

Ionisation energy / kJ mol-1

1st

578

2nd

1817

3rd

2745

4th

11577

5th

14842

6th

18379

Deduce the group number and identity of element X and explain your answer with reference to its electron configuration.

6b3 marks

First ionisation energies decrease down groups in the Periodic Table.

Explain this trend and the effect on the reactivity of groups containing metals.

6c4 marks

The ionisation energy values show a general increase across period 4 from gallium to krypton.

i)
State and explain how selenium deviates from this trend. 
[3]
ii)
Give one other element from period 2 or 3 which also deviates from this general trend, similar to selenium.
[1]

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