Definitions

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Functional group
an atom or group of atoms that determines the chemical properties of an organic compound
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Homologous series
a series of compounds containing the functional group/ general formula where members of the series differ by a -CH2- unit
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molecular formula
the formula showing the actual ratio of atoms in a compound
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empirical formula
the formula showing the simplest whole number ratio of elements
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general formula
the algebraic formula that represents all members of a homologous series
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structural formula
the formula that shows how the atoms are joined to each other
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displayed formula
shows all the covalent bonds and all the atoms in a compound
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skeletal formula
shows the carbon-carbon bonds as lines, does not show any carbon or hydrogen atoms but does show the functional groups
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structural isomerism
this is when substances have the same molecular formula but different structural formula
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stereoisomers
compounds that have the same molecular and structural formula but different arrangements of their atoms in space
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E/Z isomers
occurs in compounds having C=C bonds where there are two different groups on each carbon of the double bond
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hydrocarbon
compounds composed of hydrogen and carbon only
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saturated
compounds having only single bonds between carbons
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unsaturated
compounds containing at least one carbon-carbon multiple bond
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fractional distillation
separation of mixtures based on boiling point differences
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fraction
a mixture of liquids having boiling points which are close in value
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reflux
technique that allows us to perform a reaction at boiling point without evaporation of the reactants. A reflux condenser is employed to condense vapours back into the reaction vessel
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biofuel
fuels derived from recently dead biological material i.e. fuels from processing crops
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cracking
the decomposition of long chain alkanes into shorter chain alkanes and alkenes
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reforming
the conversion of alkanes into cyclic alkanes and alkenes
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isomerisation
the conversion of straight chain alkanes into branched alkanes
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free radical
species having an unpaired electron
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homolytic bond fission
when a covalent bond breaks evenly so that each of the bonded atoms retains one electron from the bond. this produces free radicals
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heterolytic bond fission
when a covalent bond breaks unevenly so that one of the bonded atoms retains both electrons from the bond. produces a positive and negative electron
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electrophile
electron pair acceptor (positive partial charge)
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nucleophile
electron pair donor (partial negative with lone pair)
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addition reaction
the joining of two molecules to form a single product molecule
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substitution reaction
an atom (or group of atoms) is replaced by another atom (or act)
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elimination reaction
when a small molecule is removed from a larger one
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enthalpy changee
an energy change measured under standard conditions
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standard conditions
temperature 298K (25*C), pressure 110kPa (1 atmosphere); solutions 1molddm-3
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exothermic reactions
reaction that releases heat energy to the surroundings (AH-) e.g. combustion, respiration
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endothermic reaction
reaction that absorbs heat energy from the surroundings (AH+) e.g. thermal decomposition, photosynthesis
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standard enthalpy of reaction
enthalpy change when the amounts shown in a reaction equation react under standard conditions
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standard enthalpy of formation
enthalpy change one one mole of a compound is formed from its elements under standard conditions
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standard enthalpy of combustion
enthalpy change when one mole of substance is completely burnt in excess oxygen under standard conditions
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specific heat capacity
the heat energy required to raise the temperature of 1 gram of substance by 1*C
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Hess's law
the enthalpy change for a reaction is independent of the route taken, provided the initial and final conditions are the same
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bond enthalpy
the average enthalpy change when 1 mole of bond of a particular type are broken in gaseous molecules
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collision theory
for a reaction to occur successfully, particles must collide with sufficient energy(>Ea)&be in correct orientation.temp increase=more have E
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activation energy
minimum energy required for a successful reaction to occur
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catalyst
a substance which increases the rate if a chemical reaction without being used up in the process. They work by lowering activation energy, so more particles have E>Ea
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heterogenous catalyst
a catalyst that is in a different state to the reactants e.g. Pt/Rd/Pd in catalytic conversion or Fe in haber process
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homogenous catalsy
a catalyst that is in the same state (phase) as the reactants e.g. chlorine radicals in ozone depletion
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le chatelier's principle
if any of the conditions of a system at equilibrium are change, the system will adjust its self in order to minimise the change
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dynamic equilibrium
rates of forward and reverse reactions are equal and so concentrations of all the species present remain constant. Cloose system required.
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Position of equilibrium
Qualitative description of the amount of products to starting materials in the equilibrium mixture
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Temperature changes
increase= shifts POE in the endothermic direction. decrease= shifts POE in the exothermic direction
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Pressure changes (gaseous systems)
increase=shifts POE in direction that leads to fewest gas moles. decrease=shifts POE in direction that leads to the most gas moles
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Catalysts
have no effect on POE or yield obtained- they speed up both forward and reverse reactions equally
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Other cards in this set

Card 2

Front

Homologous series

Back

a series of compounds containing the functional group/ general formula where members of the series differ by a -CH2- unit

Card 3

Front

molecular formula

Back

Preview of the front of card 3

Card 4

Front

empirical formula

Back

Preview of the front of card 4

Card 5

Front

general formula

Back

Preview of the front of card 5
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