IB Chemistry HL 2.2.15 Sigma and Pi Bonding Question Bank
Describe orbital overlap in sigma and pi bonds, then count each bond type in alkenes, alkynes and molecules such as HCN.
- Syllabus
- First assessment 2025
- Course
- Chemistry HL
- Level
- HL
Describe orbital overlap in sigma and pi bonds, then count each bond type in alkenes, alkynes and molecules such as HCN.
Describe the formation of σ and π bonds in an alkene.


Sigma bonds:
result from head-on/end-on overlap of orbitals / OWTTE;
Accept axial overlap of orbitals.
Accept "symmetric orbital" with respect to same plane / OWTTE.
Pi bonds:
result from sideways overlap of orbitals / OWTTE;
Accept "antisymmetric orbitals" with respect to (defining) plane (containing at least one atom) / OWTTE.