Glossary
Conceptual Understanding
The ability to grasp the underlying principles and molecular-level behavior of chemical phenomena, rather than just memorizing facts or performing calculations.
Example:
Developing a strong conceptual understanding of intermolecular forces helps predict a substance's boiling point without needing to look up data.
Dynamic Equilibrium
A state of equilibrium where the forward and reverse reactions continue to occur at equal rates, resulting in no net change in the concentrations of reactants and products.
Example:
In a saturated salt solution, salt crystals are continuously dissolving while dissolved ions are simultaneously crystallizing at the same rate, illustrating dynamic equilibrium.
Equilibrium
A state in a reversible chemical reaction where the rates of the forward and reverse reactions are equal, leading to constant concentrations of reactants and products.
Example:
In a closed bottle of soda, CO₂ gas is in equilibrium with dissolved CO₂; the rate of CO₂ dissolving equals the rate of CO₂ escaping.
Equilibrium Constant (K)
A numerical value that expresses the ratio of product concentrations to reactant concentrations at equilibrium, indicating the extent to which a reaction proceeds towards products.
Example:
If the equilibrium constant (K) for a reaction is very large, it means the reaction strongly favors the formation of products at equilibrium.
Law of Conservation of Mass
A fundamental scientific principle stating that matter cannot be created or destroyed in a chemical reaction; the total mass of reactants must equal the total mass of products.
Example:
When balancing chemical equations, we apply the Law of Conservation of Mass to ensure that the number of atoms of each element is the same on both sides of the equation.
Le Chatelier's Principle
A principle stating that if a change of condition (stress) is applied to a system in equilibrium, the system will shift in a direction that relieves the stress.
Example:
Increasing the temperature of an exothermic reaction at equilibrium will cause the system to shift towards the reactants, according to Le Chatelier's Principle, to absorb the added heat.
Particulate Models
Visual representations that depict matter as individual atoms or molecules, helping to understand chemical processes and changes at a molecular level.
Example:
A particulate model of water shows individual H₂O molecules, allowing us to visualize their arrangement and movement.
Products
The new substances that are formed as a result of a chemical reaction.
Example:
When baking soda and vinegar react, carbon dioxide gas is one of the products that causes fizzing.
Reactants
The starting substances in a chemical reaction that are consumed as the reaction proceeds to form new substances.
Example:
In the combustion of methane, CH₄ and O₂ are the reactants that combine to produce carbon dioxide and water.
Shifting Equilibrium
The process by which an equilibrium system adjusts its concentrations of reactants and products in response to a stress, moving either towards products (shift right) or reactants (shift left).
Example:
Adding more reactant to a system at equilibrium will cause the reaction to shift right, producing more product to re-establish equilibrium.