Glossary Flashcards
1
Q
acid
A
A species that releases H+ ions in aqueous solution
2
Q
activation energy
A
The minimum energy required to start a reaction by the breaking of bonds
3
Q
Actual yield
A
The amount of product obtained from a reaction
4
Q
Addition polymerisation
A
formation of a very long molecular chain, by repeated addition reactions of many unsaturated alkene molecules (monomers)
5
Q
addition reaction
A
A reaction in which a reactant is added to an unsaturated molecule to make a one saturated molecule
6
Q
adsorption
A
The process that occurs when a gas or liquid or solute is held to the surface of a solid
7
Q
alicyclic
A
containing carbon atoms joined together in a ring that is not aromatic
8
Q
aliphatic
A
Containing carbons atoms joined together in straight or branched chains
9
Q
alkali
A
A type of base that dissolves in water forming hydroxide ions, OH-(aq) ions
10
Q
alkanes
A
The hydrocarbon homologous series with single carbon-to-carbon bonds and the general formula: CnH2n+2
11
Q
alkenes
A
The hydrocarbon homologous series with at one double carbon-to-carbon bonds an the general formula: CnH2n
12
Q
alkyl group
A
A side chain formed by removing a hydrogen atom removed from an alkane parent chain, for example, CH3, C2H5, any alkyl group is often shown as R
13
Q
alkynes
A
Thee hydrocarbon homologous series with one triple carbon-to-carbon bonds and the general formula: CnH2n-2
14
Q
amount of substance
A
the quantity whose unit of the mole, used as a means of counting any species such as atoms, ions and molecules
15
Q
anhydrous
A
Containing no water molecules
16
Q
anion
A
A negatively charged ion with more electrons than protons
17
Q
aromatic
A
containing one or more benzene rings
18
Q
atom economy
A
(Sum of molar masses of desired products)/(sum of molar masses of all products)
19
Q
atomic (proton) number
A
The number of protons in the nucleus of an atom
20
Q
atomic orbital
A
A region around the nucleus that can hold up two electrons, with opposite spins
21
Q
average bond enthalpy
A
The average enthalpy change that takes place when breaking by homolytic fission 1 mol of a given type of bond in the molecules of a gaseous species.
22
Q
avogadro constant
A
The number of atoms per mole of the carbon-12isotope (6.02 x 100(23) mol-1
23
Q
base
A
A compound that neutralises an acid to form a salt
24
Q
binary compound
A
A compound containing two elements only
25
bond angle
The angle between 2 bonds at an atom
26
bond dissociation enthalpy
The enthalpy change takes place when breaking by homolytic fission 1 mol of a given bond in the molecules of a gaseous species.
27
bonded pair
A pair of electrons shared between two atoms to make a covalent bond
28
Bronsted-Lowry acid
A species that is a proton, H+ donor.
29
Bronsted-Lowry base
A species that is a proton, H+ accpetor
30
buffer solution
A system that minimises pH changes on addition of small amounts of an acid of a bas
31
carbocation
An ion that contains a positively charged carbon atom
32
catalyst
A substance that increases the rate of a chemical reaction without being used up in the process; a catalyst provide an alternative route for the reaction with lower activation energy
33
cation
A positively charged ion with fewer electrons than protons
34
chain reaction
A reaction in which the propagation steps release new radicals that continue the reaction
35
chiral carbon
A carbon atom attached to four different atoms or groups of atoms
36
chromatogram
A visible record showing the result of separation of the components of a mixture by chromatography
37
cis-trans isomerism
A special type of EIZ isomerism in which there are two non-hydrogen groups and two hydrogen atoms around the C=C double bond; the cis isomer (Z isomer) has H atoms on each carbon on the same side; the trans isomer (E isomer) has H atoms on each carbon on different sides.
38
closed system
A system isolated from its surroundings
39
collision theory
Two reacting particles must collide for a reaction to occur, and must be in the correct orientation and have sufficient energy to overcome the activation energy of the reaction
40
concentration
The amount of solute, in moles, dissolved in 1 dm3 (1000cm3) of solution
41
condensation reaction
A reaction in which two small molecules react together to form a larger molecule with elimination of a small molecule such as water
42
coordinate bond
A shared pair of electrons in which the bonded pair has been provided by one of the bonding atoms only; also called a dative covalent bond
43
covalent bond
The strong electrostatic attraction between a shared pair of electron and the nuclei of the bonded atoms
44
dative covalent
A shared pair of electrons in which the bonded pair has been provided by one of the bonding atoms only; also called a coordinate bond
45
dehydration
An elimination reaction in which water is removed from a saturated molecule to make an unsaturated molecule
46
delocalised electrons
Electrons that are shared between more than 2 atoms
47
desorption
Release of an adsorbed substance from a surface
48
dispole
A separation in electrical charge so that one atom of a polar covalent bond, or one end of a polar molecule, has a small positive charge and the other has a small negative charge.
49
displacement reaction
A reaction in which a more reactive element displaces a less reactive element from an aqueous solution of its ions
50
displayed formula
A formula showing the relative positioning of all the atoms in a molecule and the bonds between them
51
disproportionation
A redox reaction in which the same element is both oxidised and reduced
52
dynamic equilibrium
Th equilibrium that exists in a closed system when the rate of the forward reaction is equal to the rate of the reverse reaction and concentrations do not change
53
E/Z isomerism
A type of steroisomerism in which different groups attached to each carbon of a C=C double bond may be arranged differently in space because of the restricted rotation of the C=C bond.
54
electron configuration
A shorthand representation that shows how electrons occupy sub-shells in an atom
55
electronegativity
A measure of the attraction of a bonded atom for the pair of electrons in a covalent bond
56
electrophile
An atom (or group of atoms) which is attracted to an electron-rich centre or atom, where it accepts a pair of electrons to form a new covalent bond
57
electrophilic reaction
The removal of a molecule from a saturated molecule to make an unsaturated molecule
58
elimination reaction
The removal of a molecule from a saturated molecule to make an unsaturated molecule
59
empirical formula
The formula that shows the simplest whole-number ratio of atoms of each element present in a compound
60
end point
The point in a titration where the indicator changes colour; the end point indicates when the reaction is just complete
61
endothermic reaction
A reaction in which the enthalpy of the products is greater than the enthalpy of the reactants, resulting in heat being taken in from the surroundings. Positive change enthalpy
62
enthalpy (H)
The heat content that is stored in a chemical system
63
enthalpy change
The difference between the enthalpy of the products and the enthalpy of the reactants
64
enthalpy cycle
A diagram showing alternative routes between reactants and products which allows the indirect determination of an enthalpy change from other known enthalpy changes using Hess's law
65
ethalpy profile diagram
A diagram for a reaction to compares the enthalpy of the reactants with the enthalpy of the products
66
entropy
The used for the dispersal of energy an disorder within the chemicals making up the chemical system
67
equilibrium constant
A measure of the position of equilibrium; the magnitude of an equilibrium constant indicates whether there are more reactants or more products in an equilibrium system
68
equivalence point
The point in a titration at which the volume of one solution has reacted exactly with the volume of the second solution
69
esterification
A reaction in which a carboxylic acid reacts with an alcohol to form an ester and water
70
exothermic reaction
A reaction in which the enthalpy of the products is smaller than the enthalpy of the reactants, resulting in heat loss to the surroundings. Negative enthalpy change
71
fingerprint region
an area of an infrared spectrum below 1500cm-1 that gives a characteristic pattern for different compounds
72
first electron affinity
The enthalpy change that takes place when one electron is added to each atom in one mole of gaseous atoms to form one mole of gaseous 1-ions
73
first ionisation enerby
The energy required to remove one electron from each atom in one mole of gaseous atoms of an element to form one mole of gaseous 1+ions
74
fractional distillation
The separation of components in a liquid mixture by their different boiling points into fractions with different compositions
75
fragment ions
Ions formed from the breakdown of the molecular ion in a mass spectrometer
76
fragmentation
The process in mass spectrometry that causes a positive ion to split into smaller pieces, one of which is a positive fragment ion.
77
functional group
The part of the organic molecule responsible for its chemical reactions
78
general formula
The simplest algebraic formula of a memmber of a homologous series. For example, the general forrmula of the alkanes is CnH2n+2+
79
giant covalent lattice
a 3 dimensional structure of atoms, bonded together by strong covalent bonds.
80
giant ionic lattice
A 3 diimensional structure of oppositely charged ions, bonded together by strong ionic bonds.
81
giant metallic lattice
A 3 dimensional structure of positive ions and delocalised electrons, bonded together by strong metallic bonds.
82
group
A vertical column in the periodic table. Elements in a group have similar chemical properties and their atoms have the same number of outer shell electrons.
83
half-life
The time taken for the concentration of a reactant to decrease by half
84
hess's Law
If a reaction can take place by more than one route and the initial and final conditions are the same, the total enthalpy change is the same for each route.
85
heterogeneous catalysis
A reaction in which the catalyst has a different physical state from the reactants; frequently reactants are gases whilst the catalyst is a solid
86
heterogeneous equilibrium
An equilibrium in which the species making up the reactants and products have different physical states
87
heterolytic fission
The breaking of a covalent bond with both of the bonded electrons going to each atom, forming a cation (positive ion) and an anion (negative ion)
88
homogeneous catalysis
A reaction in which the catalyst and reactants are in the same physical state, which is more frequently the aqueous or gaseous state.
89
homogeneous equilibrium
An equilibrium in which all the species making up the reactants and products have the same physical state.
90
homologous series
A series of organic compounds with the same functional group but with each successive member differing by CH2.
91
homolytic fission
The breaking of a covalent bond with one of the bonded electrons going to each atom, forming two radicals.
92
hydrated
A crystalline compound containing water molecules
93
hydrocarbon
A compound of hydrogen and carbon only
94
hydrogen bond
A strong dipole-dipole attraction between an electron-deficient hydrogen atom of -NH, -OH or HF on one molecule and a lone pair of electrons on a highly electronegative atom containing N, O or F on a different molecule.
95
hydrolysis
A reaction with water that breaks a chemical compound into two compounds, the H and OH in a water molecule becomes incorporated into the two compounds.
96
induced dipole-dipole interaction
attractive forces between induced dipoles in different molecules - also called London Forces
97
infrared spectroscopy
An instrumentation method of analysis that identifes bonds from absorption of the infrared radiation of different wavelengths
98
initial rate of reaction
the change in concentration of a reactant or product per unit time at the start of the reaction: t=0
99
initiation
the first stage in a radical reaction in which radicals starts when a covalent bond is broken by homolytic fission of a covalent bond.
100
intermediate
A species formed during a reaction that reacts further and is not present in the final products.
101
intermolecular force
An attractive force between molecules. Intermolecular forces can be London forces, permanent dipole-dipole interactions or hydrogen bonding.
102
ion
A positively or negatively charged atom or a (covalently bonded) group of atoms (a polyatomic ion), where the number of electrons is different from the number of protons.
103
ionic bonding
the electrostatic attraction between positive and negative ions.
104
isotopes
Atoms of the same element with different numbers of neutrons and different masses.
105
lattice enthalpy
The enthalpy change that accompanies the formation of one mole of an ionic compound from its gaseous ions under standard conditions.
106
le Chatelier's principle
When a system in dynamic equilibrium is subjected to a external change, the system readjusts itself to minimise the effect of the change and to restore equilibrium.
107
ligand
A molecule or ion that can donate a pair of electrons to the transition metal ion.
108
ligand substitution
A reaction in which one or more ligands in a complex ion are replaced by different ligands
109
limiting reagent
The reactant that is not in excess, which will be used up first and stop the reaction
110
lone pair
An outer shell pair of electrons that is not involved in chemical bonding
111
mass number
The sum of the number of protons and neutrons in the nucleus - also known as nucleon number
112
metallic bond
The electrostatic attraction between positive metal ions and delocalised electrons
113
mobile phase
The phase that moves in chromatography
114
molar gas volume
The volume per mole of gas molecules at a stated temperature and pressure
115
molar mass (M)
the mass per mole of a substance, in units off g mol-1
116
mole
The amount of any substance containing as many elementary particles as there are carbon atoms in exactly 12g of the carbon-12isotope, that is, 6.02 x 10 to the 23 particles
117
molecular formula
A formula that shows the number and type of atoms of each element present in a molecule
118
molecular ion
The positive ion formed in mass
119
molecule
The smallest part of a covalent compound that can exist while retaining its chemical identity consisting of two or more atoms covalently bonded together
120
monomer
A small molecule that combines with many other monomers to form a polymer
121
neutralisation
A chemical reaction in which an acid and a base react together to produce a salt
122
nomenclature
A system of naming compounds
123
non-polar
with no charge separation across a bond or in a molecule
124
nucleophile
An atom (or group of atoms) which is attracted to an electron-deficient centre or atom, where it donates a pair of electrons to form a new covalent bond
125
nucleophilic substitution
A reaction in which a nucleophile is attracted to an electron-deficient carbon atom, and replaces an atom or group of atoms on the carbon atom
126
order
The power to which the concentration of a reactant is raised in the rate equation
127
overall order
The sum of the individual orders of reactants in the rate equation : m + n
128
oxidation
Loss of electrons or an increase in oxidation number
129
oxidation number
A measure of the number of electrons that an atom uses to bond with atoms of another element. Oxidation numbers are derived from a set of rules
130
oxidation state
The oxidation number
131
oxidising agent
A reagent that oxidises (takes electrons from) another species.
132
pie-bond
A bond formed by the sideways overlap of two p-orbitals, with the electron density above and the plane of the bonding atom
133
partial dissociation
the splitting of some of a species in solution into aqueous ions
134
pauling electronegativity value
A value assigned as a measure of the attraction of a bonded atom for the pair of electrons in a covalent bond
135
period
A horizontal row of elements in the periodic table. Elements show trend in properties across a period
136
periodicity
A repeating trend in properties of the elements across each period of the periodic table
137
permanent dipole
A small charge difference that does not change across a bond, with a positive charge and a negative charge partial changes on the bonded atoms; the result of the bonded atoms having different electrongativities
138
permanent dipole-dipole interaction
An attractive force between permanent dipoles in neighbouring polar molecules
139
polar covalent bond
A bond with a permanent dipole, having positive and negative partial changes on the bonded atoms
140
Polar molecule
A molecule with an overall dipole, having taken into account any dipoles across bonds and the shape of the molecule
141
polyatomic ion
An ion containing more than 1 atom
142
polymer
A large molecule formed from many thousands of repeat units of smaller molecules known as monomers
143
position of equilibrium
The relative quantities of reactants and products, indicating the extent of a reversible reaction at equilibrium
144
precipitation reaction
The formation of a solid from a solution during a chemical reaction. Precipitates are often formed when 2 aqueous solution are mixed together.
145
primary
On a carbon atom at the end of a chain
146
primary alcohol
An alcohol in which the OH group is attached to a carbon atom that is attached to two or three hydrogen atoms
147
principal quantum number (n)
A number representing the relative overall energy of each orbital, which increases with distance from the nucleus. The sets of orbitals with the same n-value are referred to as electron shells or energy levels
148
propogation
The steps that continue a free radical reaction, in which a radical reacts with a reactant molecule to form a new molecule and another radical causing a chain reaction.
149
proton number
The number of protons in the nucleus of an atom; also known as atomic number
150
radical
A species with an unpaired electron
151
rate constant
The constant that links the rate of reaction with the concentrations of the reactants raised to the powers of their orders in the rate equation
152
rate of reaction
The change in concentration of a reactant or a product in a given time.
153
rate-determining step
The slowest step in the reaction mechanism of a multi-step reaction
154
reaction mechanism
The sequence of bond breaking and bond-forming steps that shows the path taken by electrons during a reaction
155
redox reaction
A reaction involving reduction and oxidation
156
reducing agent
A reagent that reduces (adds electron to) another species
157
reduction
Gain of electrons or a decrease in oxidation number
158
reflux
The continual boiling and condensing of a reaction mixture back to the original container to ensure that the reaction takes place without the contents of the flask boiling dry.
159
relative atomic mass
the weighted mean mass of an atom of an element compared with one-twelfth of the mass of an atom of carbon -12
160
relative formula mass
the weighted mean mass of the formula unit of a compound compared with one twelfth of the mass of an atom of carbon-12
161
relative isotopic mass
The mass of an atom of an isotope compared with one-twelfth of the mass of an atom of carbon-12
162
relative molecular mass
The weighted mean mass of a molecule of a compound compared with one-twelfth of the mass of an atom of carbon-12
163
repeat unit
A specific arrangement of atoms that occurs in the structure over and over again. Repeat units are included in brackets outside of which is the symbol n
164
retention time
In gas chromatography, the time for a component to pass from the column inlet to the detector
165
reversible reaction
A reaction that takes place in both forward and reverse directions
166
sigma bond
A bond formed by the overlap of one orbital from each bonding atom, consisting of 2 electrons and with the electron density centred around a line directly between the nuclei of the 2 atoms.
167
salt
The product of a reaction in which the H- icons from the acid are replaced by metal or ammonium ions
168
saturated
containing single bonds only
169
saturated hydrocarbon
A hydrocarbon with single bonds only
170
second electron affinity
the enthalpy change that takes place when one electron is added to each ion in one mole of gaseous 1 - ions to form one mole of gaseous 2 - ions
171
second ionisation energy
The energy required to remove one electron from each ion in one mole of gaseous 1 + ions of an element to form one mole of gaseous 2+ ions
172
secondary
On a carbon atom to which 2 carbon chains are attached.
173
secondary alcohol
An alcohol in which the -OH group is attached to a carbon atom that is attached to two carbon chains and one hydrogen atom
174
shell
A group of atomic orbitals with the same principal quantum number, n . also known as a main energy level.
175
shielding effect
The repulsioh between electrons in different inner shells. Shielding reduces the net attractive force between the positive nucleus on the outer shell electrons.
176
simple molecular lattice
A three-dimensional structure of molecule, bonded together by weak intermolecular forces.
177
skeletal formula
A simplified organic formula with hydrogen atoms removed from alkyl chains, leaving just a carbon skeleton and associated functional groups.
178
specific heat capacity
The energy required to raise the temperature of 1g of a substance by 1C
179
spectator ions
Ions that are present but take no part in a chemical reaction
180
standard conditions
A pressure of 100kPa, a stated temperature, usually 298K (25C), and a concentration of 1 mol dm-3 (for reactions with aqueous solutions)
181
standard enthalpy change of atomisation
The enthalpy change that takes place when one mole of gaseous atoms forms from the element in its standard state
182
standard enthalpy change of combustion
The enthalpy change that takes place when one mole of a substance reacts completely with oxygen under standard conditions, all reactants and products being in their standard states.
183
standard enthalpy change of formation
The enthalpy change that takes place when one mole of a compound is formed from its constituent elements in their standard states under standard conditions
184
standard enthalpy change of hydration
The enthalpy change that takes place when one mole of isolated gaseous ions is dissolved in water forming one mole of aqueous ions under standard conditions.
185
standard enthalpy change of neutralisation
The enthalpy change that accompanies the reaction of an acid by a base to form one mole of H2O (I), under standard conditions, with all reactants and products in their standard states
186
standard enthalpy change of reaction
the enthalpy change that accompanies a reaction in the molar quantities expressed in a chemical equation under standard conditions, all reactants and products being in their standard states.
187
standard enthalpy change of solution
The enthalpy change that takes place when one mole of a compound is completely dissolved in water under standard conditions.
188
standard solution
A solution of known concentration
189
standard state
The physical state of a substance under standard conditions of 100kPa and a stated temperature (usually 298K)
190
stationary phase
The phase that does not move in chromatography
191
stereoisomers
Compounds with the same structural formula but with a different arrangement of the atoms in space
192
stoichiometry
The ratio of the amount, in moles, of each substance in a chemical equation (essentially the ratio of the balancing numbers)
193
strong acid
An acid that dissociates completely in solution
194
structural formula
A formula showing the minimal detail for the arrangement of atoms in a molecule
195
structural isomers
Molecules with the same molecular formula but with different structural formulae
196
sub-shell
A group of orbitals of the same type within a shell
197
substitution reaction
A reaction in which an atom or group of atoms is replaced with a different atom or group of atoms
198
surroundings
Everything that is not the chemical system
199
system
The chemicals involved in the reaction
200
termination
The step at the end of a radical substitution when two radicals combine to form a molecule
201
tertiary alcohol
An alcohol in which the -OH group is attached to a carbon atom that is attached to three carbon atoms and no hydrogen atoms
202
theoretical yield
The yield resulting from complete conversion of reactants into products
203
thermal decomposition
The breaking up of a chemical substance with heat into at least two chemical substances.
204
titre
The volume added from the burette when the volume of one solution has exactly reacted with eth other solution
205
transition element
A d-block element which forms an ion with an incomplete d-sub-shell
206
unsaturated
containing a multiple carbon-carbon bond
207
volatility
The ease at which a liquid turns into a gas. Volatility increases as boiling point decreases.
208
water of crystallisation
Water molecules that are bonded into a crystalline structure of a compound
209
weak acid
an acid that dissociates only partially in solution
