PCH 204University of IbadanOct 31, 2026
Reactivity of Organic Compounds
Structure
5 Concept Stages
Practice Exam
98+ Questions
Active Recall
Exam-Matched
Executive Topic Summary
Interactive mental model study tree.
High-Yield Exam Takeaways
- Why Molecules React: The Collision & Energy Story
- Orbital Interactions: When Empty Meets Full
- Nucleophilic Substitution: SN1 vs SN2 Mechanisms
- Elimination Reactions: E1 and E2 Mechanisms
- Electrophilic Aromatic Substitution: Benzene's Unique Reactivity
Study Tree Preview (Bite-Sized Concepts)
1Why Molecules React: The Collision & Energy Story
4 Micro-BitesMolecules Are Constantly Moving and Bumping:Picture a room packed with hyperactive ping-pong balls bouncing off walls, each other, and anything in their path. That's your molecules in a liquid or gas—never sitting still, con...
The Invisible Force That Pushes Molecules Apart:Every molecule carries electrons, and electrons repel each other. This <term def="the repulsive force between electron clouds of different molecules that prevents them from getting...
2Orbital Interactions: When Empty Meets Full
5 Micro-BitesThe Secret Meeting of Full and Empty Orbitals:Some of the most important organic reactions happen between molecules with zero charge and no dipole moments whatsoever. Take bromine adding to an alkene—intuitively, you'd expect ...
The σ* Orbital: Bromine's Hidden Empty Space:Here's where it gets fascinating. The bromine molecule (Br₂) carries an <term def="a molecular orbital higher in energy than the bonding orbitals, created by out-of-phase orbital o...
3Nucleophilic Substitution: SN1 vs SN2 Mechanisms
8 Micro-BitesThe Core Substitution Event:In <term def="a reaction where a nucleophile replaces a leaving group on an electrophilic carbon, with the nucleophile bringing its electron pair to form a new bond">nucleophilic s...
Kinetic Clues Reveal Two Different Mechanisms:Back in the 1930s, Hughes and Ingold cracked the code using reaction kinetics. They discovered two distinct patterns: some substitutions show <term def="a reaction rate proportiona...
Sample Practice Questions (Active Recall)
Q1.Which interaction best explains why two uncharged molecules with no permanent dipole moments can still undergo reaction?
AHydrogen bonding between heteroatoms in the reacting species
BElectrostatic attraction between σ bond dipoles and π bond dipoles
COrbital overlap between a filled orbital and an empty antibonding orbital
DCharge-charge repulsion between electron clouds overcoming activation energy
Q2.What condition must be met for two molecules with complementary dipoles to undergo chemical reaction upon collision?
AThe molecules must contain heteroatoms O, N, S, or P
BThe collision must possess sufficient activation energy to overcome electronic repulsion
COne molecule must possess a formal positive charge
DThe solvent must be polar protic to stabilize the transition state
Q3.Why does charge-charge repulsion between electrons prevent all molecular collisions from leading to chemical change?
ABecause π bonds cannot interact with empty orbitals directly
BBecause only cation-anion pairs can overcome this barrier
CBecause σ bonds are always stronger than the collision energy
DBecause electron cloud repulsion creates a universal repulsive force between all molecules
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