S1.3 Electron configurations Questionbank

Practice S1.3 Electron configurations with authentic IB Chemistry exam questions for both SL and HL students. This question bank mirrors Paper 1A, 1B, 2 structure, covering key topics like atomic structure, chemical reactions, and organic chemistry. Get instant solutions, detailed explanations, and build exam confidence with questions in the style of IB examiners.

Paper

Level

Question 1

HLPaper 1A

What is the total number of orbitals in the $n = 3$ shell?

Question 2

SLPaper 2

The elements sodium and magnesium are located in Period 3 of the periodic table and show predictable patterns in electron arrangement.

Write the electron configuration of sodium ( $Z = 11$ ) and magnesium ( $Z = 12$ ).

[1]

Deduce the number of core and valence electrons in each atom.

[2]

State and explain which atom has a higher first ionization energy.

[2]

Magnesium can also form a ${Mg^{2+}}$ ion. Explain how its electron configuration changes and why this ion is stable.

[2]

Question 3

SLPaper 2

Aluminium is used in electrical wiring and reflective coatings due to its chemical and physical properties.

State the atomic number of aluminium.

[1]

Write the full electron configuration of a neutral aluminium atom.

[1]

State the number of valence electrons in an aluminium atom.

[1]

Explain why aluminium tends to form a 3+ ion when it reacts.

[2]

Question 4

HLPaper 1A

Which element has the following ground-state electron configuration: [Ar] 4s¹ 3d⁵?

Question 5

HLPaper 1A

Which of the following transitions in the hydrogen atom releases the most energy?

Question 6

SL & HLPaper 1A

Which atom has the electron configuration 1s² 2s² 2p⁶ 3s² 3p⁴?

Question 7

SL & HLPaper 1A

Which orbital is filled immediately after the 3p orbital?

Question 8

SLPaper 2

The diagram below shows the 4s and 3d orbitals of an atom.

State what the boxes and arrows represent in an orbital box diagram.

[1]

State the full electron configuration for a neutral atom that would have exactly five electrons filling these orbitals.

[1]

Draw the orbital box diagram for the atom described in part 2.

[2]

Explain why the 4s orbital is filled before the 3d orbitals when electrons are added to an atom.

[2]

Question 9

HLPaper 1A

The elements $\mathrm{X}$ and $\mathrm{Y}$ have the following electronic configurations:

\begin{aligned} \mathrm{X} &\quad 1s^2\, 2s^2\, 2p^6\, 3s^2\, 3p^6\, 4s^2 \\ \mathrm{Y} &\quad 1s^2\, 2s^2\, 2p^6\, 3s^2\, 3p^5 \end{aligned}

What is the formula of the compound formed between $\mathrm{X}$ and $\mathrm{Y}$ ?

Question 10

SLPaper 2

Sodium vapour lamps are used in street lighting and emit a characteristic yellow light.

State the atomic number of sodium.

[1]

Write the full electron configuration of a neutral sodium atom.

[1]

Identify the electron that is removed when a sodium atom forms an ion and state the full electron configuration of the resulting ion.

[2]