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Junior Cycle · Junior Cycle Science

Junior Cycle Science: Atoms & the Periodic Table

How often Atoms & the Periodic Table comes up on the Science papers, every year it was asked, and questions to try.

CL Asked on 5 of the last 6 Common Level papers, most recently in 2026. most years

Atoms & the Periodic Table, Common Level(6 marks)

Quick ones on Atoms & the Periodic Table.

(a)Which particle in an atom has a negative charge?
  1. Proton
  2. Electron
  3. Neutron
(b)Where in an atom are the protons and neutrons found?
  1. Spread evenly throughout
  2. In the outer shells
  3. In the nucleus
(c)The atomic number of an element tells you the number of?
  1. Protons
  2. Shells
  3. Neutrons
Show the answers

(a) Electron

(b) In the nucleus

(c) Protons

Your turn: Common Level questions on Atoms & the Periodic Table.

Common Level

Asked on 5 of the last 6 Common Level papers, most recently in 2026. most years

Every paper, year by year

YearWhere it came up
2026Q16
2025Q5
2024Not asked
2023Q9, Q10
2022Q3
2019Q4, Q15

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

More Atoms & the Periodic Table questions

Atoms & the Periodic Table, 3 marks

Magnesium is in Group 2 and chlorine is in Group 7. What is the formula of their compound?

  1. MgCl
  2. Mg2Cl
  3. MgCl2
Show the answer

MgCl2

Group 2 elements have a combining power (valency) of 2 and Group 7 elements a valency of 1, so one Mg joins with two Cl: MgCl2, a 1 : 2 ratio.

Atoms & the Periodic Table, 3 marks

How does a mixture differ from a compound?

  1. It contains only one type of atom
  2. Its parts are not chemically joined
  3. It can never be separated by any means
Show the answer

Its parts are not chemically joined

In a mixture, like air or salt water, the substances are just mixed and can be separated physically. In a compound, like water, the elements are chemically bonded.

Other Science topics

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