AS2 Chemistry Vocabulary Flashcards

Comprehensive vocabulary list based on the AS2 Chemistry specification for organic chemistry, thermodynamics, and kinetics.

Empirical formula

A formula which shows the simplest whole number ratio of atoms of each element in a compound.

Molecular formula

A formula which shows the actual number of atoms of each element in a molecule.

Molar gas volume

The volume of one mole of gas under specified conditions of temperature and pressure

Homologous series

Compounds which have the same general formula, similar chemical properties, show a gradation in physical properties and successive members differ by a $CH_2$ unit.

Functional group

Reactive group within a compound.

Structural isomers

Molecules which have the same molecular formula but a different structural formula.

Geometric isomers

Molecules with the same structural formula, but different arrangement of atoms due to the presence of one or more $C=C$ bond.

Saturated hydrocarbon

Contains no $C=C$ or $C\equiv C$ bond.

Hydrocarbon

Contains hydrogen and carbon only.

Substitution

Replacing one atom or group with a different atom or group.

Homolytic fission

Bond breaking in which one of the shared electrons goes to each atom.

Heterolytic fission

Bond breaking in which both electrons in the shared pair go to a single atom.

Radical

A particle with an unpaired electron.

Unsaturated hydrocarbon

Contains at least one $C=C$ or $C\equiv C$ bond.

Sigma bond

A covalent bond formed by the linear overlap of atomic orbitals.

Pi bond

A covalent bond formed by the sideways overlap of p orbitals.

Bond length

The distance between the nuclei of two covalently bonded atoms.

Hydrogenation

Addition of a hydrogen molecule across a $C=C$.

Electrophile

An ion or molecule that attacks regions of high electron density.

Primary carbocation

A carbocation which has one carbon atom directly bonded to the positively charged carbon.

Secondary carbocation

A carbocation which has two carbon atoms directly bonded to the positively charged carbon.

Tertiary carbocation

A carbocation which has three carbon atoms directly bonded to the positively charged carbon.

Polymerisation

Joining together of many small molecules (monomers) to form a large molecule.

Monomers

Many small molecules which join together to form a polymer.

Polymer

A large molecule formed when monomers join together.

Primary halogenoalkane

A halogenoalkane which has one carbon atom directly bonded to the carbon atom that is bonded to the halogen (exceptions are halomethanes).

Secondary halogenoalkane

A halogenoalkane which has two carbon atoms directly bonded to the carbon atom that is bonded to the halogen.

Tertiary halogenoalkane

A halogenoalkane which has three carbon atoms directly bonded to the carbon atom that is bonded to the halogen.

Reflux

Repeated boiling and condensing of a (reaction) mixture.

Hydrolysis

Breaking up molecules by reaction with water.

Nucleophile

An ion or molecule, with a lone pair of electrons, that attacks regions of low electron density.

Elimination

A reaction in which a small molecule is removed from a larger molecule.

Miscibility

Liquids which mix in all proportions i.e. form a single layer.

Primary alcohol

An alcohol which has one carbon atom directly bonded to the carbon atom that is bonded to the $-OH$ group (exception is methanol).

Secondary alcohol

An alcohol which has two carbon atoms directly bonded to the carbon atom that is bonded to the $-OH$ group.

Tertiary alcohol

An alcohol which has three carbon atoms directly bonded to the carbon atom that is bonded to the $-OH$ group.

Ground state (infrared spectroscopy)

A molecular vibration which is in the lowest possible energy state.

Wavenumber

The reciprocal of the wavelength and it is measured in $cm^{-1}$.

Endothermic

A reaction in which the enthalpy of the products is greater than the enthalpy of the reactants.

Exothermic

A reaction in which the enthalpy of the products is less than the enthalpy of the reactants.

Standard enthalpy change

Change in heat energy at constant pressure, measured at standard conditions.

Standard enthalpy of combustion

The enthalpy change when one mole of a substance is completely burnt in oxygen under standard conditions.

Standard enthalpy of formation

The enthalpy change when one mole of a compound is formed from its elements under standard conditions.

Standard enthalpy of neutralisation

The enthalpy change when one mole of water is produced in a neutralisation reaction under standard conditions.

Conservation of energy

Energy cannot be created or destroyed but it can change from one form to another.

Hess’s Law

The enthalpy change for a reaction is independent of the route taken, provided the initial and final conditions are the same.

Average bond enthalpy

The energy required to break one mole of a given bond averaged over many compounds.

Reaction rate

The change of the concentration (amount) of a reactant or product with respect to time.

Catalyst

A substance which increases the rate of a chemical reaction but does not get used up.

Activation energy

The minimum amount of energy required for a reaction to occur.

Reversible

A reaction which goes in both the forward and backward directions.

Dynamic (equilibria)

Rate of forward reaction is equal to the rate of the backward reaction.

Equilibrium

A reversible reaction in which the amount of each reactant / product remains constant.

Homogeneous

A reaction in which all the reactants and products are in the same physical state.

Heterogeneous (equilibria)

A reaction in which all the reactants and products are not in the same physical state.

Heterogeneous (catalyst)

The catalyst is in a different phase from the reactants.

s-block element

An element which has an atom with highest energy/outer electron in an s-subshell (orbital).

Solubility

The maximum mass of solute that will dissolve in $100\,\text{g}$ of solvent at a stated temperature.