Electrons, energy levels and atomic orbitals: past paper questions

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• Question 1May/June 2026, paper 13Multiple choice1 mark

  What is the electronic configuration of ${\text{Cr}}^{3+}$?

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• Question 1Oct/Nov 2025, paper 11Multiple choice1 mark

  What is the electronic configuration for the particle ${}_{13}^{27}{\text{Al}}^{+}$?

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• Question 2Oct/Nov 2024, paper 11Multiple choice1 mark

  Compound X contains two elements, Y and Z. Element Y is in Period 2 of the Periodic Table. In one atom of element Y, the p sub-shell has all three orbitals occupied; only one of these three orbitals is fully occupied. Element Z is in Period 3 of the Periodic Table.

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• Question 2Oct/Nov 2023, paper 12Multiple choice1 mark

  The second ionisation energy of oxygen is greater than the second ionisation energy of fluorine. Which factor explains this difference?

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• Question 1May/June 2026, paper 22Structured14 marks

  Oxygen reacts with many elements. State the total number of electrons that occupy the 2p sub-shell in an oxygen atom.

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• Question 1Oct/Nov 2025, paper 12Multiple choice1 markHas a diagram

  What is the electrons in boxes notation for the ${\text{Fe}}^{3+}$ ion?

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• Question 1May/June 2023, paper 12Multiple choice1 markHas a diagram

  When chlorine gas is analysed in a mass spectrometer ${}^{35}{\text{Cl}}^{+}$ ions are detected. Which row is correct?

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• Question 1Oct/Nov 2025, paper 13Multiple choice1 mark

  What is the electronic configuration for the particle ${}_{13}^{27}{\text{Al}}^{+}$?

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• Question 1Oct/Nov 2024, paper 21Structured16 marks

  Cobalt, rhodium and iridium are metals in the same group of the Periodic Table. The shorthand electronic configuration of cobalt is [Ar]$3{\text{d}}^{7}4{\text{s}}^2$. Identify what is meant by [Ar] by giving its full electronic configuration.

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• Question 2May/June 2023, paper 12Multiple choice1 mark

  Which species is a free radical?

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• Question 1Oct/Nov 2025, paper 22Structured10 marks

  Manganese, Mn, and its compounds are widely used in many chemical reactions. Mn is usually found as a single isotope, manganese-55. Determine the number of protons, neutrons and electrons in an atom of manganese-55.

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• Question 1Oct/Nov 2024, paper 22Structured9 marksHas a diagram

  Vanadium, niobium and tantalum are metals in the same group of the Periodic Table. The shorthand electronic configuration of vanadium in the ground state is $[\text{Ar}]3{\text{d}}^{3}4{\text{s}}^2$.

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• Question 17May/June 2023, paper 12Multiple choice1 mark

  L, M and N are three different elements from Period 3 of the Periodic Table. L is the element whose atoms have three unpaired electrons in its 3p sub-shell. M is the element with the highest electrical conductivity in the period.

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• Question 14May/June 2025, paper 11Multiple choice1 mark

  Which statement about a 3p orbital is correct?

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• Question 1Oct/Nov 2024, paper 23Structured16 marks

  Cobalt, rhodium and iridium are metals in the same group of the Periodic Table. The shorthand electronic configuration of cobalt is [Ar]3d^74s^2. Identify what is meant by [Ar] by giving its full electronic configuration.

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• Question 20May/June 2023, paper 13Multiple choice1 mark

  $\mathrm{H}\mathrm{C}\mathrm{N}$ has been detected in interstellar gas. The molecules below have also been detected in interstellar gas. Which molecule contains the same total number of valence shell (outer shell) electrons as $\mathrm{H}\mathrm{C}\mathrm{N}$?

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• Question 1May/June 2025, paper 13Multiple choice1 mark

  Which isolated gaseous atom has a total of five electrons occupying spherically shaped orbitals?

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• Question 4May/June 2024, paper 12Multiple choice1 mark

  In which pairs are both species free radicals?

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• Question 2May/June 2025, paper 21Structured11 marksHas a diagram

  A sample of iron is analysed using a mass spectrometer. The mass spectrum shows three isotopes of iron are present in the sample. Define isotopes.

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• Question 4May/June 2024, paper 13Multiple choice1 markHas a diagram

  This question is about the first ionisation energies of magnesium and neon. Which row is correct?

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• Question 2May/June 2025, paper 22Structured10 marks

  A sample of iron contains three different isotopes and has a relative atomic mass, $A_{\text{r}}$, of 55.8. Define relative atomic mass.

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• Question 3May/June 2024, paper 22Structured12 marksHas a diagram

  Describe what is meant by dynamic equilibrium.

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• Question 1May/June 2025, paper 23Structured10 marks

  The chemical properties of an element are related to the electronic configuration of its atoms. Give the full electronic configuration of a fluorine atom.

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• Question 2May/June 2024, paper 41Structured12 marksHas a diagram

  Define transition element.

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