Virtual Lessons

Lesson 1 of 4

Alkene Bonding

This virtual lesson introduces the structure and bonding in alkenes, exploring the nature of the carbon-carbon double bond and what makes alkenes significantly more reactive than alkanes.

The lesson opens by examining the bonding within alkenes, distinguishing between sigma bonds and pi bonds. A sigma bond is formed by the direct overlap of orbitals along the internuclear axis, while a pi bond results from the sideways overlap of adjacent p orbitals above and below the plane of the molecule.

The concept of sp2 hybridisation is then explored, explaining how the three sp2 hybrid orbitals arrange themselves into a trigonal planar geometry with bond angles of 120 degrees. This shape, along with the unhybridised p orbital responsible for the pi bond, is central to understanding alkene reactivity.

The consequences of the double bond for restricted rotation around the carbon-carbon bond are also covered, along with how this rigidity gives rise to stereoisomerism in alkenes, explored further in later lessons.

This lesson establishes the structural and electronic foundations needed to understand the addition reactions and mechanisms that follow in subsequent parts of this topic.