This PowerPoint lesson provides a clear, structured explanation of the electrophilic addition reactions of alkenes, focusing on reaction mechanisms and product prediction required at IBDP Chemistry Higher Level. Designed for first assessment 2025, it supports HL students in developing secure mechanistic understanding and confidence with exam-style questions.

Electrophilic addition is a reaction in which an electron-rich carbon–carbon double bond reacts with an electrophile, breaking the π bond and forming new σ bonds via a carbocation intermediate. This lesson builds this definition carefully and shows how alkene structure influences reaction pathways and final products.

The PowerPoint begins by revisiting key ideas such as symmetrical and unsymmetrical alkenes, polarity, heterolytic fission, electrophiles, nucleophiles, and carbocation formation. Students are guided step-by-step through the mechanisms for reactions between alkenes and halogens, hydrogen halides, and water, including acid-catalysed hydration using sulfuric acid. Curly arrow notation, intermediate species, and correct mechanistic sequencing are emphasised throughout.

A major focus is placed on unsymmetrical alkenes, carbocation stability, and prediction of the major product. Markovnikov’s rule is introduced as a shortcut and explicitly linked back to the stability of primary, secondary, and tertiary carbocations, ensuring conceptual understanding rather than rote learning.

The lesson includes starter activities, clearly defined learning outcomes, worked examples, practice questions, and answers that reflect IB command terms and markscheme expectations. It is suitable for direct teaching, guided practice, or revision in the lead-up to assessments.

File type included: PowerPoint (.pptx)
Last updated: January 2026 – explanations refined, mechanisms clarified, and HL scope checked against the 2025 syllabus.