Physical Sciences: Chemistry Vocabulary

A comprehensive set of vocabulary flashcards covering organic chemistry, reaction rates, chemical equilibrium, acids and bases, and electrochemical reactions based on the course notes.

Homologous series

A series of organic compounds that can be described by the same general formula OR in which one member differs from the next with a $CH_2$ group.

Saturated compounds

Compounds in which there are no multiple bonds between C atoms in their hydrocarbon chains.

Unsaturated compounds

Compounds with one or more multiple bonds between C atoms in their hydrocarbon chains.

Functional group

A bond or an atom or a group of atoms that determine(s) the physical and chemical properties of a group of organic compounds.

Structural isomer

Organic molecules with the same molecular formula, but different structural formulae.

Chain isomers

Same molecular formula, but different types of chains.

Positional isomers

Same molecular formula, but different positions of the side chain, substituents, or functional groups on the parent chain.

Functional isomers

Same molecular formula, but different functional groups.

Heat of reaction

The energy absorbed or released in a chemical reaction.

Exothermic reactions

Reactions that release energy.

Endothermic reactions

Reactions that absorb energy.

Activation energy

The minimum energy needed for a reaction to take place.

Activated complex

The unstable transition state from reactants to products.

Reaction rate

The change in concentration of reactants or products per unit time.

Catalyst

A substance that increases the rate of a chemical reaction without itself undergoing a permanent change.

Open system

A system that continuously interacts with its environment.

Closed system

A system that is isolated from its surroundings.

Reversible reaction

A reaction where the products can be converted back to reactants and vice versa.

Chemical equilibrium

A dynamic equilibrium when the rate of the forward reaction equals the rate of the reverse reaction.

Le Chatelier's principle

When the equilibrium in a closed system is disturbed, the system will re-instate a new equilibrium by favouring the reaction that will oppose the disturbance.

Arrhenius theory

Acids produce hydrogen ions ($H^+$/$H_3O^+$/hydronium ions) in aqueous solution. Bases produce hydroxide ions ($OH^-$) in aqueous solution.

Lowry-Brønsted theory

An acid is a proton ($H^+$ ion) donor. A base is a proton ($H^+$ ion) acceptor.

Strong acid

Ionises completely in water to form a high concentration of $H_3O^+$ ions.

Weak acid

Ionises incompletely in water to form a low concentration of $H_3O^+$ ions.

Strong base

Dissociates completely in water to form a high concentration of $OH^-$ ions.

Weak base

Dissociate/ionise incompletely in water to form a low concentration of $OH^-$ ions.

Concentrated acids/bases

Contain a large amount (number of moles) of acid/base in proportion to the volume of water.

Dilute acids/bases

Contain a small amount (number of moles) of acid/base in proportion to the volume of water.

Ampholyte

A substance that can act as either acid or base.

Hydrolysis

The reaction of a salt with water.

Equivalence point of a titration

The point at which the acid/base has completely reacted with the base/acid.

Endpoint of a titration

The point where the indicator changes colour.

Galvanic cell

A cell in which chemical energy is converted to electrical energy.

Oxidation (electron transfer)

A loss of electrons.

Reduction (electron transfer)

A gain of electrons.

Oxidation (oxidation numbers)

An increase in oxidation number.

Reduction (oxidation numbers)

A decrease in oxidation number.

Oxidising agent

A substance that is reduced/gains electrons.

Reducing agent

A substance that is oxidised/loses electrons.