OCR-A A-level Chemistry

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183 Terms

1
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relative isotopic mass
mass of an atom of an isotope compared to 1/12 the mass of an
atom of carbon-12
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relative atomic mass
average mass of the atoms of an
element
taking account of all of the isotopes
compared to 1/12 the mass of an
atom of carbon-12
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relative molecular mass
average mass of a molecule
compared to 1/12 the mass of an
atom of carbon-12
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isotopes
atoms of the same element with
the same number of protons
but different numbers of neutrons
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spectator ions
species which are not changing physical state or oxidation state... not in an ionic equation
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mole
amount of substance in grams which contains the same number of particles as there are atoms in 12g of carbon-12
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empirical formula
simplest whole number ratio of atoms of each element in a compound
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general formula
algebraic formula
for a homologous series
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molecular formula
actual number of atoms of each element in a molecule
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structural formula
minimum detail required to understand the structure of a molecule
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displayed formula
shows all the covalent bonds in a molecule
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skeletal formula
shown by removing hydrogen atoms from alkyl chains, leaving just a carbon skeleton and associated functional groups
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% yield
(actual yield/theoretical yield) x 100
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% atom economy
mass of desired product / total mass of reactants x 100
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Bronsted-Lowry acid
proton donor
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Bronsted-Lowry base
proton acceptor
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alkali
soluble base which releases OH⁻ ions in solution
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salt
ionic compound that forms when H⁺ ion in an acid is replaced by a metal ion or the ammonium ion
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strong acid
acid which
completely dissociates
in aqueous solution
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weak acid
acid which partially dissociates
in aqueous solution
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% uncertainty
(uncertainty/measurement) x 100 x number of measurements
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oxidation
addition of oxygen
loss of hydrogen
loss of electrons
increase in oxidation state
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reduction
loss of oxygen
gain of hydrogen
gain of electrons
decrease in oxidation state
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disproportionation
simultaneous
oxidation and reduction
of the same element
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oxidising agent
electron acceptor
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reducing agent
electron donor
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orbital
region of space which can be
occupied by a maximum of 2
electrons
with opposite spin
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ionic bond
electrostatic attraction between positive metal ions and negative non-metal ions
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metallic bond
electrostatic attraction between positive metal ions
and delocalised electrons.
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covalent bond
electrostatic attraction between
a pair of bonded nuclei
and a bonding pair of electrons
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dative bond
electrostatic attraction between
a pair of bonded nuclei
and a bonding pair of electrons
which originate from one of the
bonded atoms
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BeCl₂
Be is in Grp2
2 outer electrons
2 bp
repel equally
get as far apart as possible

linear
180°
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BF₃
B is in Grp3
3 outer electrons
3 bp
repel equally
get as far apart as possible

trigonal planar
120°
B is in Grp3
3 outer electrons
3 bp
repel equally
get as far apart as possible

trigonal planar
120°
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CH₄
C is in Grp4
4 outer electrons
4 bp
repel equally
get as far apart as possible

tetrahedral
109.5°
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NH₃
N is in Grp5
5 outer electrons
3 bp and 1 lp
lp : bp repulsion > bp : bp repulsion
get as far apart as possible

trigonal pyramid
107°
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H₂O
O is in Grp6
6 outer electrons
2 bp and 2 lp
lp : lp repulsion > lp : bp repulsion > bp : bp repulsion
get as far apart as possible

V-shape / Bent / Non-linear
104.5°
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SF₆
S is in Grp6
6 outer electrons
6 bp
repel equally
get as far apart as possible

Octahedral
90° and 180°
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electronegativity
ability of an atom to attract
electrons within a covalent bond
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London forces
induced dipole-dipole forces
instantaneous dipole-induced dipole forces
dispersion forces

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
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Alkane to Haloalkane
Halogen UV light

Rad Sub
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Alkene to Alkane
H2, Ni catalyst

Reduction

Heterogenious Catalysis
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Alkene to Polyalkene
High pressure and a catalyst

Addition Polymerisation
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Alkene to Dihaloalkane
X2 rtp

Elec Add
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Alkene to Haloalkane
HX rtp

Elec Add