GRADE 12 CAPS Physical Sciences Paper 2: Chemistry Definitions and General theory

Vocabulary practice flashcards covering basic organic chemistry, reaction rates, chemical equilibrium, and acid-base theories based on the lecture transcript.

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.

Alkanes

Organic molecules with a carbon-carbon single bond ($C-C$) structure containing only $C-H$ and $C-C$ single bonds.

Alkenes

Organic molecules containing a carbon-carbon double bond ($C=C$) functional group.

Alkynes

Organic molecules containing a carbon-carbon triple bond ($C \neq C$) functional group.

Haloalkanes

Organic molecules containing a halogen atom ($X = F, Cl, Br, I$) bonded to a saturated $C$ atom.

Alcohols

Organic molecules containing a hydroxyl group bonded to a saturated $C$ atom.

Aldehydes

Organic molecules containing a formyl group ($C-H$ with a double bond to oxygen on the same carbon).

Ketones

Organic molecules containing a carbonyl group bonded to two $C$ atoms.

Carboxylic acids

Organic molecules containing a carboxyl group functional group.

Esters

Organic molecules containing a functional group with an oxygen atom double bonded to a carbon atom that is also single bonded to another oxygen atom within the chain.

Dipole-dipole forces

Intermolecular forces between two polar molecules.

Induced dipole forces or London forces

Intermolecular forces between non-polar molecules.

Hydrogen bonding

Forces between molecules in which hydrogen is covalently bonded to nitrogen, oxygen or fluorine; a special case of dipole-dipole forces.

Boiling point

The temperature at which the vapour pressure of a substance equals atmospheric pressure.

Melting point

The temperature at which the solid and liquid phases of a substance are at equilibrium.

Vapour pressure

The pressure exerted by a vapour at equilibrium with its liquid in a closed system.

Organic molecules

Molecules containing carbon atoms.

Molecular formula

A chemical formula that indicates the type of atoms and the correct number of each in a molecule.

Structural formula

A compound formula showing which atoms are attached to which; atoms are represented by symbols and lines represent ALL the bonds.

Condensed structural formula

A notation that shows the way in which atoms are bonded together in the molecule but does not show all bond lines.

Hydrocarbon

Organic compounds that consist of hydrogen and carbon only.

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

Molecules with the same molecular formula, but different types of chains.

Positional isomers

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

Functional isomers

Molecules with the same molecular formula, but different functional groups.

Hydrohalogenation

The addition of a hydrogen halide to an alkene.

Halogenation

The reaction of a halogen ($Br_2, Cl_2$) with a compound.

Hydration

The addition of water to a compound.

Hydrogenation

The addition of hydrogen to an alkene.

Dehydrohalogenation of haloalkanes

The elimination of hydrogen and a halogen from a haloalkane.

Dehydration of alcohols

The elimination of water from an alcohol.

Cracking of alkanes

The chemical process in which longer chain hydrocarbon molecules are broken down to shorter more useful molecules.

Hydrolysis

The reaction of a compound or salt with water.

Macromolecule

A molecule that consists of a large number of atoms.

Polymer

A large molecule composed of smaller monomer units covalently bonded to each other in a repeating pattern.

Monomer

Small organic molecules that can be covalently bonded to each other in a repeating pattern to form a polymer.

Polymerisation

A chemical reaction in which monomer molecules join to form a polymer.

Addition polymerisation

A reaction in which small molecules join to form very large molecules by adding on double bonds.

Condensation polymerisation

Molecules of two monomers with different functional groups undergo condensation reactions with the loss of small molecules, usually water.

Heat of reaction (ΔH)

The energy absorbed or released in a chemical reaction.

Exothermic reactions

Chemical reactions that release energy ($\text{ΔH} < 0$).

Endothermic reactions

Chemical reactions that absorb energy ($\text{ΔH} > 0$).

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

Substance that increases the rate of a reaction by providing an alternative path of lower activation energy, therefore decreasing the net activation energy.

Chemical equilibrium

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

Reversible reaction

A reaction where products can be converted back to reactants.

Open system

A system that continuously interacts with its environment, as opposed to a closed system which is isolated.

Arrhenius Acid

A substance that produces hydrogen ions ($H^+$) or hydronium ions ($H_3O^+$) when it dissolves in water.

Arrhenius Base

A substance that produces hydroxide ions ($OH^-$) when it dissolves in water.

Lowry-Brønsted Theory Acid

An acid is defined as a proton ($H^+$ ion) donor.

Lowry-Brønsted Theory Base

A base is defined as a proton ($H^+$ ion) acceptor.

Strong acids

Acids that ionise completely in water to form a high concentration of $H_3O^+$ ions.

Weak acids

Acids that ionise incompletely in water to form a low concentration of $H_3O^+$ ions.

Strong bases

Bases that dissociate completely in water to form a high concentration of $OH^-$ ions.

Weak bases

Bases that dissociate or ionise incompletely in water to form a low concentration of $OH^-$ ions.

Concentrated acids/bases

Solutions containing a large amount (number of moles) of acid or base in proportion to the volume of water.

Dilute acids/bases

Solutions containing a small amount (number of moles) of acid or base in proportion to the volume of water.

Conjugate acid-base pairs

When the acid, $HA$, loses a proton, its conjugate base, $A^-$, is formed; when the base, $A^-$, accepts a proton, its conjugate acid, $HA$, is formed.

Ampholyte

A substance that can act as either an acid or as a base (also called an amphiprotic substance).

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.

Auto-ionisation of water

The reaction of water with itself to form $H_3O^+$ ions and $OH^-$ ions.