Subjects · Leaving Cert Chemistry
Leaving Cert Chemistry: Trends
How often Trends comes up on the Chemistry papers, every year it was asked, and questions to try.
HL Asked on 10 of the last 10 Higher Level papers, most recently in 2026. banker
OL Asked on 6 of the last 10 Ordinary Level papers, most recently in 2025. most years
June 2027 is the first exam on the new Chemistry course. These come from the 2016–2026 papers, so read them as a guide.
Quick ones on Trends.
- Oxygen
- Fluorine
- Chlorine
- Neon
- Fluorine
- Helium
- Decreases
- Stays the same
- Increases
Show the answers
(a) Fluorine
(b) Helium
(c) Decreases
Higher Level
Asked on 10 of the last 10 Higher Level papers, most recently in 2026. banker
Every paper, year by year
| Year | Where it came up |
|---|---|
| 2026 | Q5 |
| 2025 | Q5 |
| 2024 | Q4(e) |
| 2023 | Q4(d) |
| 2022 | Q4(c) |
| 2021 | Q5 |
| 2019 | Q5 |
| 2018 | Q4(b) |
| 2017 | Q5 |
| 2016 | Q4(c) |
Links open the State Examinations Commission’s paper for that year.
More Trends questions
Trends, 3 marks
Definition of first ionisation energy?
- Energy released when one mole of electrons is added to one mole of gaseous atoms
- Energy needed to break one mole of covalent bonds
- Energy needed to remove one mole of electrons from one mole of gaseous atoms
Show the answer
Energy needed to remove one mole of electrons from one mole of gaseous atoms
The atoms must be in the gaseous state and isolated, so that no bonding or neighbouring particles affect the value.
Trends, 3 marks
Why is a positive ion always smaller than the atom it came from?
- It has gained an extra energy level when it lost electrons
- It has fewer electrons pulled in by the same nuclear charge
- It has fewer protons in its nucleus than the neutral atom it came from
Show the answer
It has fewer electrons pulled in by the same nuclear charge
Losing electrons, often the whole outer level, leaves the remaining electrons attracted by an unchanged number of protons, so they are drawn in closer.
Trends, 3 marks
Why is a negative ion always larger than the atom it came from?
- Extra electrons repel; nuclear charge is the same
- It has gained extra protons in its nucleus
- It has lost one of its energy levels
Show the answer
Extra electrons repel; nuclear charge is the same
The added electrons increase repulsion in the outer level, while the same number of protons pulls on more electrons, so the ion swells.
Ordinary Level
Asked on 6 of the last 10 Ordinary Level papers, most recently in 2025. most years
Every paper, year by year
| Year | Where it came up |
|---|---|
| 2026 | Not asked |
| 2025 | Q4(b) |
| 2024 | Q5 |
| 2023 | Q5 |
| 2022 | Not asked |
| 2021 | Q4(d) |
| 2019 | Not asked |
| 2018 | Not asked |
| 2017 | Q4(d) |
| 2016 | Q5 |
Links open the State Examinations Commission’s paper for that year.
More Trends questions
Trends, 2 marks
Going down group 1, the reactivity of the metals?
- Decreases
- Stays the same
- Increases
Show the answer
Increases
The outer electron is further from the nucleus, so it is lost more easily. Potassium reacts faster with water than sodium.
Other Chemistry topics
- Acids and bases
- Atomic structure
- Chemical equilibrium
- Concentration
- Covalent bonding
- Electronegativity
- Fuels and heats of reaction
- Functional groups
- Gas laws
- Hydrocarbons
- Mandatory experiments
- Organic reactions
- Oxidation and reduction
- pH
- Rates of reaction
- Shapes of molecules
- The mole
- The periodic table
- Volumetric analysis
- Water treatment
- Electron configuration
- Formulas and equations
- Organic synthesis
- Radioactivity
- Instrumentation and separation
- Ionic bonding
- Intermolecular forces
- Electrochemistry
- Environmental chemistry
- Isomerism
- Industrial chemistry
- Lab safety
- States of matter