CCEA Definitions AS2 Flashcards
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.
Molecular Gas Volume
The volume of one mole of gas under specified conditions of temperature and pressure.
Percentage Yield
% yield= actual yield of product/theoretical yield of product x 100
Atom economy
% atom economy = mass of desired products/total mass of products x100
Homologous series
Compounds which have the same general formula, similar chemical properties, show a gradation in physical properties and successive members differ by a CH2 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 which have the same structural formula, but different arrangements of atoms due to the presence of one or more C=C bond.
Saturated hydrocarbon
Contains only single bonds.
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.
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
Liquid which mix in all proportions.
Primary alcohol
An alcohol which has one carbon atom directly bonded to the carbon atom that is bonded to the -OH group (exc 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 (IR spectroscopy)
A molecule vibration which is in its 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 conditions
298K and 100kPa
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 element under standard conditions
Standard enthalpy of neutralisation
The enthalpy change when one mole of water is produced in a neutralisation reaction under standard conditions.
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 in the shared pair go to a single 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
Contains at least one C=C or C///C
Conservation of energy
Energy cannot be created or destroyed but it can change from one form into 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 concentration 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 Reaction
A reaction which goes in both the forward and backward direction
Dynamic Equilibrium
Rate of forward reaction is equal to the rate of the backwards 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
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 the outer electron in an s-orbital
Solubility
The maximum mass of solute that will dissolve in 100g of solvent at a stated temperature
