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Leaving Cert Physics: The atom

How often The atom comes up on the Physics papers, every year it was asked, and questions to try.

HL Asked on 7 of the last 10 Higher Level papers, most recently in 2025. most years

OL Asked on 4 of the last 10 Ordinary Level papers, most recently in 2026.

June 2027 is the first exam on the new Physics course. These come from the 2016–2026 papers, so read them as a guide.

The atom, Higher Level(6 marks)

Quick ones on The atom.

(a)Who carried out the gold-foil scattering experiment under Rutherford's supervision?
  1. Cockcroft and Walton
  2. Geiger and Marsden
  3. Bohr and Einstein
(b)In the Geiger–Marsden experiment, which particles were fired at the thin gold foil?
  1. Neutrons
  2. Beta particles
  3. Alpha particles
(c)Why was the gold-foil experiment carried out in an evacuated chamber?
  1. Alpha particles have a very short range in air
  2. To keep the gold foil electrically charged
  3. To stop the gold foil from melting
Show the answers

(a) Geiger and Marsden

(b) Alpha particles

(c) Alpha particles have a very short range in air

Your turn: Higher Level questions on The atom.

Higher Level

Asked on 7 of the last 10 Higher Level papers, most recently in 2025. most years

Every paper, year by year

YearWhere it came up
2026Not asked
2025Q6(l)
2024Q13
2023Q6(l)
2022Q6(j)
2021Q11
2019Q8
2018Not asked
2017Q9
2016Not asked

Links open the State Examinations Commission’s paper for that year.

More The atom questions

The atom, 2 marks

How were the scattered alpha particles detected in the Geiger–Marsden experiment?

  1. The spread of the leaves of a gold-leaf electroscope near the foil
  2. A rise in temperature shown by a thermometer behind the foil
  3. Flashes of light on a zinc sulfide screen, viewed through a microscope
Show the answer

Flashes of light on a zinc sulfide screen, viewed through a microscope

Each alpha particle hitting the zinc sulfide screen made a tiny flash (scintillation). The screen and microscope could be moved round to count flashes at each angle.

The atom, 3 marks

A very small number of alpha particles were deflected through more than 90°. What did Rutherford conclude?

  1. The alpha particles were pulled back by the negative electrons in the gold atoms
  2. The positive charge and nearly all the mass are concentrated in a tiny nucleus
  3. The positive charge is spread evenly through the whole of the atom
Show the answer

The positive charge and nearly all the mass are concentrated in a tiny nucleus

Only a tiny, dense, positive centre could repel a fast alpha particle back the way it came. Electrons are far too light to turn an alpha particle round.

The atom, 3 marks

Why could Rutherford's nuclear model not explain a stable atom?

  1. An orbiting electron is accelerating, so it should radiate energy and spiral into the nucleus
  2. The positive nucleus should repel the orbiting electrons, so they would fly right out of the atom
  3. The neutrons in the nucleus should decay, giving out energy that pushes the electrons away
Show the answer

An orbiting electron is accelerating, so it should radiate energy and spiral into the nucleus

Classical physics says an accelerating charge radiates energy. An orbiting electron would lose energy and spiral in, giving a continuous spectrum. Atoms are stable and give line spectra.

Ordinary Level

Asked on 4 of the last 10 Ordinary Level papers, most recently in 2026.

Every paper, year by year

YearWhere it came up
2026Q12
2025Q6(k)
2024Not asked
2023Q12
2022Not asked
2021Q6(k)
2019Not asked
2018Not asked
2017Not asked
2016Not asked

Links open the State Examinations Commission’s paper for that year.

More The atom questions

The atom, 2 marks

What is the charge on a proton?

  1. Negative
  2. No charge
  3. Positive
Show the answer

Positive

A proton has a positive charge. An electron has an equal negative charge. A neutron has no charge.

The atom, 2 marks

Which particle in an atom has no charge?

  1. Electron
  2. Neutron
  3. Proton
Show the answer

Neutron

The neutron is neutral. It is found in the nucleus with the protons. The electrons (negative) move around the nucleus.

The atom, 2 marks

Where in an atom are the protons and neutrons found?

  1. In the nucleus
  2. Orbiting the nucleus
  3. Spread evenly through the atom
Show the answer

In the nucleus

Protons and neutrons are packed into the tiny nucleus at the centre. Electrons move around the nucleus in energy levels (shells).

Other Physics topics

All of Leaving Cert Physics