random movement of the electron cloud causes an uneven charge distribution and sets up an instantaneous dipole in one molecule
this induces a dipole in a neighbouring molecule and leads to a temporary attraction
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permanent dipole-permanent dipole force
intermolecular force between permanent dipoles in neighbouring polar molecules
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hydrogen bond
strong intermolecular force between a δ⁺H atom covalently bonded to N, O or F on one molecule
and a lone pair of electrons on N, O or F of a neighbouring molecule
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periodicity
repeating pattern of chemical and physical properties across different periods
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first ionisation energy
energy required to remove 1 mole of electrons from 1 mole of gaseous atoms to form 1 mole of +1 gaseous ions
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second ionisation energy
energy required to remove 1 mole of electrons from 1 mole of +1 gaseous ions to form 1 mole of +2 gaseous ions
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exothermic
bond making process
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endothermic
bond breaking process
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activation energy
minimum amount of energy required to start a chemical reaction
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standard conditions (⦵)
298 K 100 kPa all solutions 1 moldm⁻³
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standard enthalpy change of formation △fH⦵
enthalpy change when...
1 mole of a compound is formed from its elements in their standard states
under standard conditions of 298K and 100kPa
with all reactants and products in their standard states
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standard enthalpy change of combustion △cH⦵
enthalpy change when...
1 mole of a substance completely combusts in excess oxygen
under standard conditions of 298K and 100kPa
with all reactants and products in their standard states
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standard enthalpy change of reaction △rH⦵
enthalpy change when...
the reaction occurs in the molar ratio specified by the balanced equation
under standard conditions of 298K and 100kPa
with all reactants and products in their standard states
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standard enthalpy change of neutralisation △neutH⦵
enthalpy change when...
1 mole of water is formed from a reaction between an acid & a base
under standard conditions of 298K and 100kPa
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Q
Q \= mc△T
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△H
△H \= ⁻Q/1000n
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mean bond enthalpy
energy required to break 1 mole of gaseous covalent bonds
averaged over a number of different molecules
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Hess' law
enthalpy change of a reaction is independent of the route taken
providing the initial and final conditions are the same
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catalyst
speeds up a reaction
regenerated doesn't appear in the overall equation provides an alternative reaction pathway with a lower activation energy
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heterogenious catalyst
catalyst in a different physical state to the reactants
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homogenious catalyst
catalyst in the same physical state as the reactants
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dynamic equilibrium
forward rate \= back rate concentrations of all reactants and products are constant closed system
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Le Chatelier's principle
when the conditions of a system in equilibrium are changed
the position of equilibrium will shift to reduce the effect of the change
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saturated
single carbon-carbon bonds only
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unsaturated
compound with one or more double or triple carbon-carbon bonds
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aliphatic
compound containing carbon and hydrogen joined together in straight chains, branched chains or non-aromatic rings
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alicyclic
aliphatic compound arranged in non-aromatic rings with or without side chains
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aromatic
compound containing at least one benzene ring
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homologous series
series of organic compounds with the.. same functional group same general formula successive member differs by CH₂
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functional group
atom, group of atoms or region of a molecule responsible for its reactions and properties
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structural isomers
same molecular formula different structural formula
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stereoisomers
same molecular formula same structural formula different arrangement of atoms in space
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radical
species with an unpaired electron
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homolytic fission
covalent bond breaking process where each atom receives one of the bonding electrons
forms radicals
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heterolytic fission
covalent bond breaking process where one atom receives both of the bonding electrons
forms ions
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sigma bond
covalent bond formed by end-on overlap of orbitals
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pi bond
covalent bond formed by sideways overlap of p-orbitals
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3 types of stereoisomers
E-Z isomers
cis-trans isomers
optical isomers
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E-Z isomerism
type of stereoisomerism
restricted rotation about a C\=C double bond
each C in the C\=C double bond attached to 2 different atoms or groups
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cis-trans isomerism
type of stereoisomerism
restricted rotation about a C\=C double bond
a particular atom or group is attached to each of the C atoms in the C\=C double bond
like groups on opposite sides of the double bond - trans like groups on same side of the double bond - cis
also found in square planar and octahedral complexes
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optical isomerism
type of stereoisomerism
occurs when there is an asymmetric (chiral) carbon atom attached to 4 different atoms or groups resulting in non-superimposable mirror images (enantiomers)
occurs where there are two or three bidentate ligands in an octahedral complex
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nucleophile
electron pair donor
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electrophile
electron pair acceptor
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carbocation
positively charged organic species
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1° carbocation
positive C is bonded to 1 other C
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2° carbocation
positive C is bonded to 2 other Cs
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3° carbocation
positive C is bonded to 3 other Cs
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Markownikoff's rule
rule applied to determine the product mixture when...
an asymmetric alkene reacts with an asymmetric electrophile
major product is formed from the more stable 2° or 3° carbocation
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primary alcohol
C to which the OH is bonded, is bonded to 1 other C
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secondary alcohol
C to which the OH is bonded, is bonded to 2 other Cs
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tertiary alcohol
C to which the OH is bonded, is bonded to 3 other Cs
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hydrocarbon
compound that contains carbon and hydrogen only
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CFC
compound that contains chlorine, fluorine and carbon only
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HFC
compound that contains hydrogen, fluorine and carbon only
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fingerprint region
complicated region of an IR spectrum below 1500 cm⁻¹ caused by vibrations of the whole molecule compared to a spectral database for a positive ID
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molecular ion
molecule minus an electron
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fragmentation
process where a molecular ion breaks into a positive ion and a radical