Studied by 2 PeopleTags & Description
relative isotopic mass
mass of an atom of an isotope compared to 1/12 the mass of an atom of carbon-12
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
relative molecular mass
average mass of a molecule compared to 1/12 the mass of an atom of carbon-12
isotopes
atoms of the same element with the same number of protons but different numbers of neutrons
spectator ions
species which are not changing physical state or oxidation state... not in an ionic equation
mole
amount of substance in grams which contains the same number of particles as there are atoms in 12g of carbon-12
empirical formula
simplest whole number ratio of atoms of each element in a compound
general formula
algebraic formula for a homologous series
molecular formula
actual number of atoms of each element in a molecule
structural formula
minimum detail required to understand the structure of a molecule
displayed formula
shows all the covalent bonds in a molecule
skeletal formula
shown by removing hydrogen atoms from alkyl chains, leaving just a carbon skeleton and associated functional groups
% yield
(actual yield/theoretical yield) x 100
% atom economy
mass of desired product / total mass of reactants x 100
Bronsted-Lowry acid
proton donor
Bronsted-Lowry base
proton acceptor
alkali
soluble base which releases OH⁻ ions in solution
salt
ionic compound that forms when H⁺ ion in an acid is replaced by a metal ion or the ammonium ion
strong acid
acid which completely dissociates in aqueous solution
weak acid
acid which partially dissociates in aqueous solution
% uncertainty
(uncertainty/measurement) x 100 x number of measurements
oxidation
addition of oxygen loss of hydrogen loss of electrons increase in oxidation state
reduction
loss of oxygen gain of hydrogen gain of electrons decrease in oxidation state
disproportionation
simultaneous oxidation and reduction of the same element
oxidising agent
electron acceptor
reducing agent
electron donor
orbital
region of space which can be occupied by a maximum of 2 electrons with opposite spin
ionic bond
electrostatic attraction between positive metal ions and negative non-metal ions
metallic bond
electrostatic attraction between positive metal ions and delocalised electrons.
covalent bond
electrostatic attraction between a pair of bonded nuclei and a bonding pair of electrons
dative bond
electrostatic attraction between a pair of bonded nuclei and a bonding pair of electrons which originate from one of the bonded atoms
BeCl₂
Be is in Grp2 2 outer electrons 2 bp repel equally get as far apart as possible
linear 180°
BF₃
B is in Grp3 3 outer electrons 3 bp repel equally get as far apart as possible
trigonal planar 120°
CH₄
C is in Grp4 4 outer electrons 4 bp repel equally get as far apart as possible
tetrahedral 109.5°
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°
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°
SF₆
S is in Grp6 6 outer electrons 6 bp repel equally get as far apart as possible
Octahedral 90° and 180°
electronegativity
ability of an atom to attract electrons within a covalent bond
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
permanent dipole-permanent dipole force
intermolecular force between permanent dipoles in neighbouring polar molecules
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
periodicity
repeating pattern of chemical and physical properties across different periods
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
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
exothermic
bond making process
endothermic
bond breaking process
activation energy
minimum amount of energy required to start a chemical reaction
standard conditions (⦵)
298 K 100 kPa all solutions 1 moldm⁻³
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
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
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
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
Q
Q = mc△T
△H
△H = ⁻Q/1000n
mean bond enthalpy
energy required to break 1 mole of gaseous covalent bonds
averaged over a number of different molecules
Hess' law
enthalpy change of a reaction is independent of the route taken
providing the initial and final conditions are the same
catalyst
speeds up a reaction
regenerated doesn't appear in the overall equation provides an alternative reaction pathway with a lower activation energy
heterogenious catalyst
catalyst in a different physical state to the reactants
homogenious catalyst
catalyst in the same physical state as the reactants
dynamic equilibrium
forward rate = back rate concentrations of all reactants and products are constant closed system
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
saturated
single carbon-carbon bonds only
unsaturated
compound with one or more double or triple carbon-carbon bonds
aliphatic
compound containing carbon and hydrogen joined together in straight chains, branched chains or non-aromatic rings
alicyclic
aliphatic compound arranged in non-aromatic rings with or without side chains
aromatic
compound containing at least one benzene ring
homologous series
series of organic compounds with the.. same functional group same general formula successive member differs by CH₂
functional group
atom, group of atoms or region of a molecule responsible for its reactions and properties
structural isomers
same molecular formula different structural formula
stereoisomers
same molecular formula same structural formula different arrangement of atoms in space
radical
species with an unpaired electron
homolytic fission
covalent bond breaking process where each atom receives one of the bonding electrons
forms radicals
heterolytic fission
covalent bond breaking process where one atom receives both of the bonding electrons
forms ions
sigma bond
covalent bond formed by end-on overlap of orbitals
pi bond
covalent bond formed by sideways overlap of p-orbitals
3 types of stereoisomers
E-Z isomers
cis-trans isomers
optical isomers
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
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
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
nucleophile
electron pair donor
electrophile
electron pair acceptor
carbocation
positively charged organic species
1° carbocation
positive C is bonded to 1 other C
2° carbocation
positive C is bonded to 2 other Cs
