Ceist Eile

Ceist Eile is in development. Features, questions and prices may change while we refine it.

Subjects · Leaving Cert Chemistry

Leaving Cert Chemistry: Shapes of molecules

How often Shapes of molecules 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 4 of the last 10 Ordinary Level papers, most recently in 2026.

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

Shapes of molecules, Higher Level(6 marks)

Quick ones on Shapes of molecules.

(a)Shape of a water molecule, H2O?
  1. Linear
  2. V-shaped (bent)
  3. Pyramidal
(b)Theory used to predict the shapes of simple molecules?
  1. The octet rule (eight outer electrons)
  2. Le Chatelier's principle (equilibrium)
  3. Valence shell electron pair repulsion
(c)Shape of a carbon dioxide molecule, CO2?
  1. Linear
  2. Trigonal planar
  3. V-shaped
Show the answers

(a) V-shaped (bent)

(b) Valence shell electron pair repulsion

(c) Linear

Your turn: Higher Level questions on Shapes of molecules.

Higher Level

Asked on 10 of the last 10 Higher Level papers, most recently in 2026. banker

Every paper, year by year

YearWhere it came up
2026Q4(d)
2025Q10(a)
2024Q11(a)
2023Q4(c)
2022Q10(b)
2021Q10(a)
2019Q11(a)
2018Q11(a)
2017Q11(b)
2016Q11(b)

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

More Shapes of molecules questions

Shapes of molecules, 2 marks

Why is BF3 non-polar even though each B-F bond is polar?

  1. Boron and fluorine have equal electronegativity, so the bonds are not polar
  2. It has a lone pair on the boron that cancels the bond dipoles
  3. Its symmetrical trigonal planar shape makes the bond dipoles cancel
Show the answer

Its symmetrical trigonal planar shape makes the bond dipoles cancel

Three equal dipoles at 120 degrees add up to zero, so the molecule has no overall dipole. Shape decides polarity.

Shapes of molecules, 2 marks

Approximate H-N-H bond angle in ammonia, NH3?

  1. 90 degrees
  2. 107 degrees
  3. 120 degrees
Show the answer

107 degrees

Ammonia has 3 bond pairs and 1 lone pair. The lone pair repels more strongly, closing the angle from 109.5 to about 107 degrees.

Shapes of molecules, 2 marks

Shape of the ammonium ion, NH4+?

  1. Tetrahedral
  2. Pyramidal
  3. Square planar
Show the answer

Tetrahedral

Nitrogen has four bond pairs and no lone pair in NH4+, so the four hydrogens point to the corners of a tetrahedron.

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
2026Q5
2025Q4(c)
2024Not asked
2023Not asked
2022Not asked
2021Not asked
2019Not asked
2018Not asked
2017Q10(b)
2016Q10(c)

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

More Shapes of molecules questions

Shapes of molecules, 2 marks

Bond angle in a methane molecule, CH4?

  1. 90 degrees
  2. 180 degrees
  3. 109.5 degrees
Show the answer

109.5 degrees

In a tetrahedral shape the four bonds point to the corners of a tetrahedron, 109.5 degrees apart.

Other Chemistry topics

All of Leaving Cert Chemistry