1.5.1
Collision Theory
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Collision Theory
Collision theory is the theory of how reactions happen.

When will a reaction happen?
- For a reaction between two molecules to happen, they must come into close proximity with each other.
- For a particular reaction to happen, several conditions must be met:
- The correct part of the molecules must collide.
- The molecules must collide with enough energy to react.

Steric factor
- The steric factor is the fancy name for saying that the location of a collision matters.
- For example, if you were trying to react the OH bond in ethanol (CH3CH2OH), a collision with the CH3 group wouldn't do anything.

Activation energy
- The activation energy is the energy needed for a reaction to happen.
- The activation energy is used to break the bonds in the reactants before new bonds can form in the products.
- For both reasons of activation energy and steric factor, most collisions do not result in a reaction.
1Physical Chemistry
1.1Atomic Structure
1.1.1Fundamental Particles1.1.2Isotopes & Mass Number1.1.3Mass Spectrometry1.1.4Electron Shells, Sub-Shells & Orbitals1.1.5Electron Configuration1.1.6Ionisation Energy1.1.7Factors Affecting Ionisation Energies1.1.8Trends of Ionisation1.1.9Specific Impacts on Ionisation Energies1.1.10End of Topic Test - Atomic Structure1.1.11A-A* (AO3/4) - Atomic Structure
1.2Amount of Substance
1.2.1Relative Masses1.2.2The Mole1.2.3The Ideal Gas Equation1.2.4Empirical & Molecular Formulae1.2.5Balanced Equations1.2.6Percentage Yield1.2.7A-A* (AO3/4) - Percentage Yield1.2.8Atom Economy1.2.9End of Topic Test - Amount of Substance1.2.10A-A* (AO3/4) - Substances & Yield1.2.11Diagnostic Misconceptions - Moles
1.3Bonding
1.3.1Ionic Bonding1.3.2Covalent & Dative Bonding1.3.3Carbon Structures1.3.4Metallic Bonding1.3.5Physical Properties1.3.6Shapes of Molecules1.3.7Polarity1.3.8Intermolecular Forces1.3.9Intermolecular Forces 21.3.10End of Topic Test - Bonding1.3.11Exam-Style Question - Shape of Molecules1.3.12A-A* (AO3/4) - Bonding1.3.13Diagnostic Misconceptions - Ions1.3.14Diagnostic Misconceptions - Ionic & Covalent1.3.15Diagnostic Misconceptions - Phase Change1.3.16Diagnostic Misconceptions - Boiling1.3.17Diagnostic Misconceptions - Polar Bonds
1.4Energetics
1.5Kinetics
1.6Equilibria
2Physical Chemistry 2 (A2 Only)
2.1Thermodynamics (A2 Only)
2.2Rate Equations (A2 Only)
2.3The Equilibrium Constant Kp (A2 Only)
2.4Electrochemical Cells (A2 Only)
2.5Acids & Bases (A2 Only)
2.5.1Brønsted-Lowry Acids & Bases (A2 Only)2.5.2pH (A2 Only)2.5.3The Ionic Product of Water (A2 Only)2.5.4Weak Acids & Bases (A2 Only)2.5.5pH Curves & Titrations (A2 Only)2.5.6pH Curves & Titrations 2 (A2 Only)2.5.7Buffer Solutions (A2 Only)2.5.8End of Topic Test - Acids & Bases2.5.9Exam-Style Question - Weak Acids2.5.10A-A* (AO3/4) - Acids & Bases2.5.11Diagnostic Misconceptions - Ammonia is an Alkali2.5.12Diagnostic Misconceptions - Water's Neutrality2.5.13Diagnostic Misconceptions - Concentrate & Strength
3Inorganic Chemistry
3.1Periodicity & Trends
4Inorganic Chemistry 2 (A2 Only)
4.1Period 3 (A2 Only)
4.2Transition Metals (A2 Only)
4.2.1General Properties (A2 Only)4.2.2Substitution Reactions (A2 Only)4.2.3Shapes of Complex Ions (A2 Only)4.2.4Colours of Ions (A2 Only)4.2.5Variable Oxidation States (A2 Only)4.2.6Titrations (A2 Only)4.2.7Homogeneous Catalysts (A2 Only)4.2.8Heterogeneous Catalysts (A2 Only)4.2.9End of Topic Test - Transition Metals4.2.10A-A* (AO3/4) - Transition Metals
4.3Reactions of Ions in Aqueous Solutions (A2 Only)
5Organic Chemistry 1
5.1Introduction
5.2Alkanes
5.3Halogenoalkanes
5.4Alkenes
5.5Alcohols
5.6Organic Analysis
5.7A-A* (AO3/4) - Organic 1
6Organic Chemistry 2 (A2 Only)
6.1Optical Isomerism (A2 Only)
6.2Aldehydes & Ketones (A2 Only)
6.3Carboxylic Acids & Esters (A2 Only)
6.4Aromatic Chemistry (A2 Only)
6.5Amines (A2 Only)
6.6Polymers (A2 Only)
6.7Biological Organic (A2 Only)
6.8Organic Synthesis (A2 Only)
6.9NMR Spectroscopy (A2 Only)
6.10Chromatography (A2 Only)
6.11A-A* (AO3/4) - Organic 2
Jump to other topics
1Physical Chemistry
1.1Atomic Structure
1.1.1Fundamental Particles1.1.2Isotopes & Mass Number1.1.3Mass Spectrometry1.1.4Electron Shells, Sub-Shells & Orbitals1.1.5Electron Configuration1.1.6Ionisation Energy1.1.7Factors Affecting Ionisation Energies1.1.8Trends of Ionisation1.1.9Specific Impacts on Ionisation Energies1.1.10End of Topic Test - Atomic Structure1.1.11A-A* (AO3/4) - Atomic Structure
1.2Amount of Substance
1.2.1Relative Masses1.2.2The Mole1.2.3The Ideal Gas Equation1.2.4Empirical & Molecular Formulae1.2.5Balanced Equations1.2.6Percentage Yield1.2.7A-A* (AO3/4) - Percentage Yield1.2.8Atom Economy1.2.9End of Topic Test - Amount of Substance1.2.10A-A* (AO3/4) - Substances & Yield1.2.11Diagnostic Misconceptions - Moles
1.3Bonding
1.3.1Ionic Bonding1.3.2Covalent & Dative Bonding1.3.3Carbon Structures1.3.4Metallic Bonding1.3.5Physical Properties1.3.6Shapes of Molecules1.3.7Polarity1.3.8Intermolecular Forces1.3.9Intermolecular Forces 21.3.10End of Topic Test - Bonding1.3.11Exam-Style Question - Shape of Molecules1.3.12A-A* (AO3/4) - Bonding1.3.13Diagnostic Misconceptions - Ions1.3.14Diagnostic Misconceptions - Ionic & Covalent1.3.15Diagnostic Misconceptions - Phase Change1.3.16Diagnostic Misconceptions - Boiling1.3.17Diagnostic Misconceptions - Polar Bonds
1.4Energetics
1.5Kinetics
1.6Equilibria
2Physical Chemistry 2 (A2 Only)
2.1Thermodynamics (A2 Only)
2.2Rate Equations (A2 Only)
2.3The Equilibrium Constant Kp (A2 Only)
2.4Electrochemical Cells (A2 Only)
2.5Acids & Bases (A2 Only)
2.5.1Brønsted-Lowry Acids & Bases (A2 Only)2.5.2pH (A2 Only)2.5.3The Ionic Product of Water (A2 Only)2.5.4Weak Acids & Bases (A2 Only)2.5.5pH Curves & Titrations (A2 Only)2.5.6pH Curves & Titrations 2 (A2 Only)2.5.7Buffer Solutions (A2 Only)2.5.8End of Topic Test - Acids & Bases2.5.9Exam-Style Question - Weak Acids2.5.10A-A* (AO3/4) - Acids & Bases2.5.11Diagnostic Misconceptions - Ammonia is an Alkali2.5.12Diagnostic Misconceptions - Water's Neutrality2.5.13Diagnostic Misconceptions - Concentrate & Strength
3Inorganic Chemistry
3.1Periodicity & Trends
4Inorganic Chemistry 2 (A2 Only)
4.1Period 3 (A2 Only)
4.2Transition Metals (A2 Only)
4.2.1General Properties (A2 Only)4.2.2Substitution Reactions (A2 Only)4.2.3Shapes of Complex Ions (A2 Only)4.2.4Colours of Ions (A2 Only)4.2.5Variable Oxidation States (A2 Only)4.2.6Titrations (A2 Only)4.2.7Homogeneous Catalysts (A2 Only)4.2.8Heterogeneous Catalysts (A2 Only)4.2.9End of Topic Test - Transition Metals4.2.10A-A* (AO3/4) - Transition Metals
4.3Reactions of Ions in Aqueous Solutions (A2 Only)
5Organic Chemistry 1
5.1Introduction
5.2Alkanes
5.3Halogenoalkanes
5.4Alkenes
5.5Alcohols
5.6Organic Analysis
5.7A-A* (AO3/4) - Organic 1
6Organic Chemistry 2 (A2 Only)
6.1Optical Isomerism (A2 Only)
6.2Aldehydes & Ketones (A2 Only)
6.3Carboxylic Acids & Esters (A2 Only)
6.4Aromatic Chemistry (A2 Only)
6.5Amines (A2 Only)
6.6Polymers (A2 Only)
6.7Biological Organic (A2 Only)
6.8Organic Synthesis (A2 Only)
6.9NMR Spectroscopy (A2 Only)
6.10Chromatography (A2 Only)
6.11A-A* (AO3/4) - Organic 2
Practice questions on Collision Theory
Can you answer these? Test yourself with free interactive practice on Seneca — used by over 10 million students.
- 1Conditions for a reaction to happen:Fill in the list
- 2What information is contained within enthalpy profile diagrams?Fill in the list
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