Definitions Flashcards
(98 cards)
1
Q
acid
A
A species that releases H+ ions in aqueous solution
2
Q
acid dissociation constant
A
The equilibrium constant that shows the extent of dissociation of a weak acid
For a weak acid HA (Aq), Ka= [H+(aq)][A-(aq)]/[HA(aq)]
3
Q
acid-base pair
A
A pair of two species that transform into each other by gain or loss of a proton
4
Q
activation energy
A
The minimum energy required to start a reaction by the breaking of bonds
5
Q
actual yield
A
The amount of product obtained from a reaction
6
Q
addition polymerisation
A
Formation of a very long molecular chain by repeated addition reactions of many unsaturated alkene molecules (monomers)
7
Q
addition reaction
A
A reaction in which a reactant is added to an unsaturated molecule to make a one saturated molecule
8
Q
adsorption
A
The process that occurs when a gas or liquid or solute is half to the surface of a solid
9
Q
alicyclic
A
Containing carbon atoms joined together in a ring that is not aromatic
10
Q
aliphatic
A
Containing carbon atoms joined together in straight or branched chains
11
Q
alkali
A
A type of base that dissolves in water forming hydroxide ions, OH-(aq) ions
12
Q
alkanes
A
The hydrocarbon homologous series with single carbon-to carbon bond and the general formula CnH2n+2
13
Q
alkenes
A
The hydrocarbon homologous series with at one double carbon-to-carbon bond and the general formula CnH2n
14
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
15
Q
alkynes
A
The hydrocarbon homologous series with one triple carbon-to-carbon bonds and the general formula CnH2n-2
16
Q
amount of a substance
A
The quantity whose unit of the model, used as a means of counting any species such as atoms, ions and molecules
17
Q
anhydrous
A
Containing no water molecules
18
Q
anion
A
Negatively charged ion with more electrons than protons
19
Q
aromatic
A
Containing one or more benzene rings
20
Q
atom economy
A
(Sum of molar masses of desired products)/ (sum of molar masses of all products)
21
Q
atomic (proton) number
A
The number of protons in the nucleus of an atom
22
Q
atomic orbital
A
A region around the nucleus that can hold up two electrons with opposite spots
23
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 molecule of a gaseous species
24
Q
Avogadro constant Na
A
The number of atoms per mole of the carbon-12 isotope (6.02 x 10^-23 mol^-1)
25
base
A compound that neutralises an acid to form a salt
26
binary compound
A compound contains two elements only
27
bond angle
The angle between two bonds at an atom
28
bond dissociation enthalpy
The enthalpy change that takes place when breaking by homiletic fission 1 mol of s given bond in the molecules of a gaseous species
29
bonded pair
A pair of electrons shared between two atoms to make a covalent bond
30
Brønsted-Lowry acid
A species that is a proton, H+ donor
31
Brønsted-Lowry base
A species that is a proton, H+ acceptor
32
buffer solution
A system that minimises pH changes on addition of small amounts of an acid or a base
33
carbocation
An ion that contains positively charged carbon atom
34
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 a lower activation energy
35
cation
A positively charged ions with fewer electrons than protons
36
chain reaction
A reaction in which the propagation steps release new radicals that continue the reaction
37
chemical shift (delta)
A scale, in ppm that compares the frequency of the reference TMS at delta=0ppm
38
chiral carbon
A carbon atom attached to four different atoms or groups of atoms
39
chromatogram
A visible record showing the result of separation of the components of a mixture by chromatography
40
cis-trans isomerism
A special type of E/Z 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
41
closed system
A system isolated from its surroundings
42
collision theory
Two reacting particles must collide for a reaction to occur, and must be in the correct orientation and have diffiencet energy to overcome the activation energy of the reaction
43
complex ion
A transition metal ion bonded to ligands by coordinate bonds (dative covalent bonds)
44
concentration
The amount of solute, in moles, dissolved in 1dm^3 (1000cm^3) of solution
45
condensation reaction
A reaction in which two small molecules react together to form a larger molecules
46
conjugate acid
A species that releases a proton to form a conjugate base
47
conjugate acid
A species that accepts a proton to form a conjugate acid
48
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
49
coordination number
The total number of coordinate bonds formed between a central metal ions and ligands
50
covalent bond
The strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms
51
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
52
dehydration
An elimination reaction in which water is removed from a saturated molecule to make an unsaturated molecule
53
delocalised electrons
Electrons that are shared between more than two atoms
54
desorption
Release of an adsorbed substance from a surface
55
dipole
A separation in electrical charged so that one atom of a polar covalent bond, or one end of a polar molecule, has a small positive charge (delta+) and the other has a small negative charge (delta-)
56
displacement reaction
A reaction in which a more reactive element displaces a less reactive element form an aqueous solution of its ions
57
displayed formula
A formula showing the relative positioning of all the atoms in a molecule and the bonds between them
58
disproportionation
A redox reaction in which the same element is both oxidised and reduced
59
dynamic equilibrium
The equilibrium that exists in a closed system when the rate of the forward reaction is equal to the rate of the reverse reaction and the concentrations of not change
60
E/Z isomerism
A type of stereoisomerism 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 fo the C=C bond
61
electron configuration
A shorthand representation that shows how electrons occur sub shells in an atom
62
electronegativity
A measure of the attraction of a bonded Aton for the pair of electrons in a covalent bond
63
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
64
electrophilic addition
An addition reaction in which the first step is attack by an electrophile on a region of high electron density
65
electrophilic substitution
A type of substitution reaction in which an electrophile is attracted to an electron-rich centre or atom, where it accepts a pair of electrons to form a new covalent bond
66
elimination reaction
The removal of a molecule from a saturated molecule to make an unsaturated molecule
67
empirical formula
The formula that shows the simplest whole number ratio of atoms of each element present in a compound
68
enantiomers
Stereoisomers that are non-superimposable mirror images of each other; also called optical isomers
69
end point
The point in a titration where the indicator changes colour; the end point indicates when the reaction is complete
70
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
71
enthalpy, H
The heat content that is stored in a chemical system
72
enthalpy change deltaH
The difference between the enthalpy of the products and the enthalpy of the reactants
73
enthalpy cycle
A diagram showing alternative routes between reactant and products which allows the indirect determination of an enthalpy change from other known enthalpy changes using Hess's law
74
enthalpy profile diagram
A diagram for the reaction to compare the enthalpy of the reactants with the enthalpy of the products
75
entropy
The used for the dispersal of energy and disorder within the chemicals making up the chemical system
76
equilibrium constant
A measurement of the position of equilibrium; the magnitude of an equilibrium constant indicates whether there are more reacts or more products in an equilibrium system
77
equivalence point
The point in a titration at which the volume of one solution has reacted exactly with the volume of the second solution
78
esterification
A reaction in which a carboxylic acid reacts with an alcohol to form an ester and water
79
exothermic reaction
A reaction in which the enthalpy of the products is ambler than the enthalpy of the reactants, resulting in heat loss to the surroundings (delta H is negative)
80
fingerprint region
An area of the infrared spectrum below 1500cm-1 that gives a characteristic pattern for different compounds
81
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
82
first ionisation energy
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
83
fractional distillation
The separation of components in a liquid mixture by their different boiling points into reactions with different compositions
84
fragment ions
Ions formed from the breakdown of the molecular ion in a mass spectrometer
85
fragmentation
The process in mass spectroscopy that causes a positive ion to split into smaller pieces one of which is a positive fragment ion
86
free energy change deltaG
The balance between enthalpy entropy and temperature for a process given by deltaG=deltaH-TdeltaS. A process is feasible when delta G < 0
87
functional group
The part of the organic molecule responsible for its chemical reactions
88
general formula
The simplest algebraic formula of a member of a homologous series e.g. the general formula of the alkanes is CnH2n+2
89
giant covalent lattice
A three dimensional structure of atoms, bonded together by strong covalent bonds
90
giant ionic lattice
A three dimensional structure of oppositely changed ions, bonded together by strong ionic bonds
91
giant metallic structure
A three dimensional structure of positive ions and delocalised electrons, bonded together by strong by strong metallic bonds
92
group
A vertical column in the periodic table. Elements in a group have similar chemical properties and the atoms have the same number of outer shell electrons
93
half life
The time taken for the concentration of a reactant to decrease by half
94
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
95
heterogenous catalysts
A reaction in which the catalyst has a different physical state from he reactants; frequently reactants are gases whilst the catalyst is a solid
96
heterogenous equilibrium
An equilibrium in which the species making up the reactants and products have different physical states
97
heterolytic fission
The breaking of a covalent bond forming a cation (positive ion) and an anion (negative ion)
98
homogenous catalysts
A reaction in which the catalyst and reactants are in the same physical state which is most frequently the aqueous or gaseous states
