CourseCourseConceptConceptDocumentDocument

CAIE A-Level Chemistry A2 29.3 Shapes of Aromatic Organic Molecules and Bonds Questions

Practise explaining aromatic geometry through sp² hybridisation, σ bonding and sideways p-orbital overlap.

Syllabus
2028–2030
Course
Chemistry 9701
Level
A2

Exam points

  • state that benzene is a planar hexagonal molecule with 120° bond angles and sp²-hybridised carbon atoms
  • describe σ bonds as end-on overlap involving carbon sp² orbitals and hydrogen 1s orbitals where applicable
  • explain the delocalised π system as sideways overlap of parallel p orbitals above and below the ring

Covered syllabus points

29.3.1—Shape of benzene and other aromatic molecules

Question 1

[Maximum number: 2]

Describe the shape of delocalised benzene.

Include the geometry of each carbon, the C-C-H bond angle and the type of bond(s) between the carbon atoms and between the carbon and hydrogen atoms.

Question 2

[Maximum number: 2]

Ruthenium and osmium are transition metals below iron in Group 8 of the Periodic Table.

Fig. 4.1 shows another ruthenium complex.

Fig. 4.1

Fig. 4.1

This complex contains the neutral ligand pyrazine.

Figure for Question 2 — CAIE A-Level Chemistry A2

Pyrazine is an aromatic compound. The bonding and structure of pyrazine is similar to that of benzene.

Describe and explain the shape of pyrazine.
In your answer, include:
- the hybridisation of the nitrogen and carbon atoms
- how orbital overlap forms π\pi bonds between the atoms in the ring.

Question 3

[Maximum number: 1]

Benzene, C6H6\mathrm{C}_{6} \mathrm{H}_{6}, is an aromatic molecule.

State the C-C-C bond angle and the hybridisation shown by the carbon atoms in benzene. bond angle
hybridisation

All question bank results loaded