IBChemistryHLTopic QuestionsModels of the Particulate Nature of MatterElectronic Configurations

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First teaching 2023

First exams 2025

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Electronic Configurations (HL IB Chemistry)

Topic Questions

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11 mark

Using the Aufbau Principle and Hund’s rule, deduce which element below has the greatest number of unpaired electrons in its ground state.

  • Z = 13

  • Z = 14

  • Z = 15

  • Z = 16

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21 mark

Which electron transition would emit radiation of the longest wavelength?

2-1-e-q10-mcqs-ib-chemistry

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31 mark

Why is the second ionisation energy of magnesium higher than the first ionisation energy?

  • Less shielding

  • Ionic radius increases

  • Nuclear charge is increasing

  • Greater attraction between positive nucleus and outer electron

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4
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Which is true about the emission spectrum of hydrogen in the visible region?

  • The lines converge at longer wavelengths

  • The lines converge at higher frequency

  • The lines come from transitions between n=∞ and n=1

  • The lines are regularly spaced

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5
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The frequency of the point of convergence on a hydrogen emission spectrum is 32.883 x 1014 s-1.

What is the ionisation energy for one atom of hydrogen?

(h = 6.63 x 10-34 J s)

  • 2.18 x 10-18 J

  • 2.02 x 10-49 J

  • J

  • 4.96 x 1045 J

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6
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The first five ionisation energies of an element are shown below.

What element could this ionisation energy graph belong to?

successive-ionisation-energy

  • N

  • P

  • Al

  • Na

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7
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Which are correct explanation(s) for the increase in ionisation energy across a period?

I. Nuclear charge increases

II. Atomic radius decreases

III. Shielding remains constant

  • I and II only

  • I and III only

  • I and III only

  • I,II and III

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8
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Which spectrum belongs to hydrogen?

eARGWkkX_hydrogen-spectrum

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11 mark

Element X is in period 2 and has the first seven ionisation energies in kJ mol-1 as shown.

    1300    

    3380    

    5330    

    7460    

    11 010    

    13 320    

    71 200    

What is the electronic configuration of element X?

  • 1s2 2s2 2p4

  • 1s2 2s2 2p2

  • 1s2 2s2 2p3

  • 1s2 2s2 2p6

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21 mark

For the successive ionisation energies of oxygen, where would the highest jump be expected to occur?

  • second ionisation energy

  • first ionisation energy

  • seventh ionisation energy

  • sixth ionisation energy

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31 mark

Which species produces a half-filled set of p orbitals on losing an electron?

  • Li+

  • F

  • N

  • N-

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41 mark

Which statement explains why electrons pair up in orbitals before occupying an orbital of a higher energy level?

  • the energy from repulsion is greater than the jump to a higher orbital

  • electrons occupy higher energy orbitals before lower energy orbitals

  • electrons in lower orbitals have higher energies

  • the energy from repulsion is less than the jump to a higher orbital

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51 mark

Which equation is correct for the third ionization energy for the element nitrogen?

  • N+(g) → N4+(g)  + 3e-

  • N2+(g) → N3+(g)  + e-

  • N(g) → N3+(g)  + 3e-

  • N3+(g) → N4+(g)  + e-

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61 mark

A line emission spectrum occurs when

  • electrons release energy as they move from high to low energy levels

  • electrons release energy as they move from low to high energy levels

  • electrons absorb energy as they move from high to low energy levels

  • electrons absorb energy as they move from low to high energy levels

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71 mark

A spectral line that would be found in the visible spectrum of the hydrogen emission spectrum would be

  • n1 → n2

  • n2 → n3

  • n3 → n2

  • n3 → n∞

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8
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Which statement is true about the spectra shown? hydrogen-spectrum-hl

  • All the lines in R have the same energy

  • Q and S could represent line emission spectra

  • Only S could represent a line emission spectrum for hydrogen

  • P indicates the element has 4 pairs of electrons at different energy levels 

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9
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The energy absorbed at the limit of convergence for helium is 19.6 x 10-18 J per atom.

Which calculation would be used to calculate the wavelength, in m, for this electron transition?

(c = 3.00 x 108 ms-1, h = 6.63 x 10-34 Js)

  • 8.89 x 1024

  • 1.01 x 10-8

  • 4.33 x 10-59

  • 2.31 x 1058

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10
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The first ionisation energies (in kJ mol-1) of five successive elements are:

2081, 496, 738, 578, 787

What could these elements be?

  • First five elements in a period

  • Second to the sixth elements in a period

  • Last four elements of one period and the first one of the next period

  • Last element of one period and the first four elements of the next period

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11
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A period 3 element forms an oxide M2O3.

Which represents the first four successive ionisation energies of M?

  Ionisation energy / kJmol-1
  First Second Third Fourth
A. 496 4560 6940 9540
B. 578 1820 2740 11600
C. 1012 1907 2914 4964
D. 736 1450 7740 10500

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12
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Between which ionisation energies of silicon will there be the greatest difference?

  • Between the second and fourth ionisation energies

  • Between the first and third ionisation energies

  • Between the fourth and fifth ionisation energies

  • Between the fifth and sixth ionisation energies

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11 mark

There are six unpaired electrons in atoms of element Z. What could element Z be?

  • sulfur

  • iron

  • carbon

  • chromium

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21 mark

The diagram shows three orbitals labelled 1, 2 and 3. 

2-1-m-q5-mcqs-ib-chemistry

What is the correct label for each orbital?

  • px, py and pz

  • s, pz and py

  • s, px and pz

  • s, px and py

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31 mark

What is the electronic configuration of an ion with a single negative charge and atomic number 17?

  • 1s2 2s2 2p6 3s1 3p6

  • 1s2 2s2 2p6 3s2 3p6

  • 1s2 2s2 2p6 3s1 3p5

  • 1s2 2s2 2p6 3s2 3p5

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41 mark

What is the correct sequence for the orbitals shown in an atom of vanadium in order of decreasing energy?

  • 3s 3p 4s 3d

  • 4s 3d 3s 3p

  • 4s 3d 3p 3s

  • 3d 4s 3p 3s

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51 mark

The second ionisation energy of magnesium is 1451 kJ mol-1. 

Which equation correctly represents this statement?

  • Mg+(g) → Mg2+(g) + e-          ΔHӨ = -1451 kJ mol-1

  • Mg+(g) → Mg2+(g) + e-          ΔHӨ = +1451 kJ mol-1

  • Mg(g) → Mg2+(g) + 2e-         ΔHӨ  = +1451 kJ mol-1

  • Mg(g) → Mg+(g) + e-            ΔHӨ = -1451 kJ mol-1

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61 mark

X, Y and Z  are consecutive elements in the third Period of the Periodic Table. Element Y has the highest first ionisation energy and also the lowest melting point of these three elements. 

What could be the identities of X, Y and Z?

  • silicon, phosphorus, sulfur 

  • sodium, magnesium, aluminium

  • aluminium, silicon, phosphorus

  • magnesium, aluminium, silicon

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71 mark

An element in the d block of the periodic table forms a +4 ion and has the electron configuration of [Ar] 3d1.

What is the identity of the element?

  • Chromium

  • Copper

  • Vanadium

  • Silicon

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81 mark

Deduce the correct information about the element tin, Sn (Z = 50)

  Number of occupied
main energy levels		 Number of electrons in the
highest main energy level

A

4

4

B

4

14

C

5

4

D

5

14

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91 mark

Which of the following calculations gives the correct calculation to find the energy, in kJ, for a photon of blue light given the wavelength ƛ = 550 nm.

h = 6.626 x 10−34J s; c =  2.988 x 108 m s-1

  • 3.60 x 10-19

  • 3.60 x 10-31

  • 3.60 x 10-22

  • 6.63 x 10-37

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101 mark

Successive ionisation energies for an element, Y, are shown in the table below.

Electrons removed

1st

2nd

3rd

4th

5th
Ionisation energy / kJ mol-1

736

1450

7740

10500

13600

What is the most likely formula for the ion of Y?

  • Y+

  • Y2+

  • Y3+

  • Y4+

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111 mark

Values for the successive ionisation energies for an unknown element are given in the table below.

First ionisation energy / kJ mol-1

Second ionisation energy / kJ mol-1

Third ionisation energy / kJ mol-1

Fourth ionisation energy / kJ mol-1

420

3600

4400

5900

In which group of the periodic table would the unknown element be found?

  • 1

  • 2

  • 13

  • 14

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121 mark

The graph shows the first ionisation energies of some consecutive elements

x-and-y-ionisation-energiesWhich statement is correct?

  • Y is in group 13

  • Y is in group 10

  • X is in group 15

  • X is in group 18

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131 mark

Which transition on the diagram corresponds to the ionisation of hydrogen in the ground state?

ionisation-of-ground-state-hydrogen

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