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Collision Model

▶︎  Watch it animatedinteractive step-through · ~3 min · optional

The collision model says particles must collide to react, but only some collisions succeed. A successful collision needs two things: enough energy (at or above the activation energy, Eₐ) and the correct orientation. The Maxwell-Boltzmann distribution shows how many particles have enough energy; raising temperature shifts more of them above Eₐ.

UNIT 5 TOPIC 5.5 • COLLISION MODEL COLLISION MODEL MAXWELL–BOLTZMANN DISTRIBUTION Eₐ kinetic energy → number of particles lower T higher T Higher T → larger fraction of particles have E ≥ Eₐ (shaded area past Eₐ is bigger for the green curve). Higher-T peak is LOWER and BROADER, shifted right — both curves enclose equal area. COLLISIONS ✓ Effective collision — correct orientation + enough energy products ✗ Ineffective collision — poor orientation or too little energy no products COLLISION MODEL A reaction occurs only when particles collide with: ✓ Correct orientation reactants aligned so bonds can form ✓ Enough energy (E ≥ Eₐ) collision energy reaches the activation energy ✓ Sufficient collision frequency more collisions per second → faster rate Rate depends on collision frequency, orientation, and having energy ≥ Eₐ. AP Chemistry · Unit 5 · Kinetics
The collision model: molecules must collide to react, but not every collision works. A successful collision needs enough energy (at or above the activation energy, Eₐ) AND the correct orientation. Raising temperature increases the fraction of collisions above Eₐ, speeding the reaction.
Orientation Lab · Open the sandbox →

The misconceptions treat energy alone as enough (orientation matters too) and misread how temperature affects collisions (it mainly raises the fraction with sufficient energy, not just the collision count). Both energy and orientation gate a successful reaction.

The work

3 ways in · any order
Lesson
Collision Model ›

A reaction needs collisions with enough energy and the right orientation; temperature raises the energetic fraction. The lesson reasons from the Maxwell-Boltzmann picture, then closes with a ten-scenario check.

Skill check · 10 scenarios
Open lesson →
Diagnostic
10-item topic check ›

Ten items spanning the Topic 5.5 misconceptions: energy alone assumed to make a collision succeed, and temperature's effect on collision energy and count misread.

Not started · 10 items · ~15 min
Start diagnostic →
Targeted Practice
Drill a single misconception ›

Pick one of the failure modes you missed and drill it on its own. The round is adaptive: two correct in a row clears the misconception and moves you to the next.

Take the diagnostic to identify your misconceptions
Diagnostic first