Overview
This lecture covers the basics of chemical reactions, how they are represented, types of energy involved, reaction types, and related key processes such as dehydration synthesis and hydrolysis.
Chemical Reactions & Equations
- Chemical reactions involve atoms rearranging to form molecules or compounds.
- A chemical equation shows reactants (left side) and products (right side).
- Reactants are substances you start with; products are substances formed in the reaction.
- A single arrow (→) indicates an irreversible reaction; double arrows (⇌) indicate a reversible reaction.
- Example: CO₂ + H₂O ⇌ H₂CO₃ (carbonic acid formation, reversible and important for many topics).
Types of Energy in Reactions
- Energy is the capacity to do work; includes potential (stored) and kinetic (in use) energy.
- Higher kinetic energy increases molecular movement and reaction rates.
- Chemical energy is stored in bonds; breaking bonds releases energy, forming bonds may require energy input.
- Electrical energy comes from the movement of ions or charged particles.
- Mechanical energy is the transfer of energy via movement or force between objects.
Reaction Types
- Endergonic reactions store energy in products (require energy input).
- Exergonic reactions release energy from reactants (energy output exceeds energy input).
- Catabolic (decomposition) reactions break down molecules and usually release energy (exergonic).
- Anabolic (synthesis) reactions build molecules and typically store energy (endergonic).
- Exchange reactions swap components between molecules.
Synthesis & Decomposition Processes
- Dehydration synthesis joins monomers by removing water, forming polymers.
- Hydrolysis splits polymers by adding water, breaking them into monomers.
- Monomers are single building blocks; polymers are chains of monomers.
Oxidation-Reduction (Redox) Reactions
- Redox reactions involve the transfer of electrons from one molecule to another, releasing energy.
Key Terms & Definitions
- Reactant — Starting substance in a chemical reaction.
- Product — Substance formed through a chemical reaction.
- Endergonic reaction — Stores energy in products.
- Exergonic reaction — Releases energy from reactants.
- Catabolic reaction — Decomposes complex molecules into simpler ones.
- Anabolic reaction — Combines simpler molecules into complex ones.
- Exchange reaction — Swaps components between molecules.
- Dehydration synthesis — Forms polymers by removing water.
- Hydrolysis — Breaks polymers by adding water.
- Redox reaction — Transfers electrons between molecules.
Action Items / Next Steps
- Memorize the CO₂ + H₂O ⇌ H₂CO₃ reaction and its significance.
- Review this lecture in preparation for the upcoming enzyme lab in week 2.