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Chemistry A level > Glossary > Flashcards

Glossary Flashcards

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1
Q

acid

A

A species that releases H+ ions in aqueous solution

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2
Q

activation energy

A

The minimum energy required to start a reaction by the breaking of bonds

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3
Q

Actual yield

A

The amount of product obtained from a reaction

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4
Q

Addition polymerisation

A

formation of a very long molecular chain, by repeated addition reactions of many unsaturated alkene molecules (monomers)

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5
Q

addition reaction

A

A reaction in which a reactant is added to an unsaturated molecule to make a one saturated molecule

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6
Q

adsorption

A

The process that occurs when a gas or liquid or solute is held to the surface of a solid

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7
Q

alicyclic

A

containing carbon atoms joined together in a ring that is not aromatic

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8
Q

aliphatic

A

Containing carbons atoms joined together in straight or branched chains

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9
Q

alkali

A

A type of base that dissolves in water forming hydroxide ions, OH-(aq) ions

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10
Q

alkanes

A

The hydrocarbon homologous series with single carbon-to-carbon bonds and the general formula: CnH2n+2

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11
Q

alkenes

A

The hydrocarbon homologous series with at one double carbon-to-carbon bonds an the general formula: CnH2n

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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

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13
Q

alkynes

A

Thee hydrocarbon homologous series with one triple carbon-to-carbon bonds and the general formula: CnH2n-2

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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

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15
Q

anhydrous

A

Containing no water molecules

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16
Q

anion

A

A negatively charged ion with more electrons than protons

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17
Q

aromatic

A

containing one or more benzene rings

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18
Q

atom economy

A

(Sum of molar masses of desired products)/(sum of molar masses of all products)

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19
Q

atomic (proton) number

A

The number of protons in the nucleus of an atom

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20
Q

atomic orbital

A

A region around the nucleus that can hold up two electrons, with opposite spins

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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.

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22
Q

avogadro constant

A

The number of atoms per mole of the carbon-12isotope (6.02 x 100(23) mol-1

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23
Q

base

A

A compound that neutralises an acid to form a salt

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24
Q

binary compound

A

A compound containing two elements only

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25
Q

bond angle

A

The angle between 2 bonds at an atom

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26
Q

bond dissociation enthalpy

A

The enthalpy change takes place when breaking by homolytic fission 1 mol of a given bond in the molecules of a gaseous species.

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27
Q

bonded pair

A

A pair of electrons shared between two atoms to make a covalent bond

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28
Q

Bronsted-Lowry acid

A

A species that is a proton, H+ donor.

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29
Q

Bronsted-Lowry base

A

A species that is a proton, H+ accpetor

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30
Q

buffer solution

A

A system that minimises pH changes on addition of small amounts of an acid of a bas

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31
Q

carbocation

A

An ion that contains a positively charged carbon atom

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32
Q

catalyst

A

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

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33
Q

cation

A

A positively charged ion with fewer electrons than protons

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34
Q

chain reaction

A

A reaction in which the propagation steps release new radicals that continue the reaction

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35
Q

chiral carbon

A

A carbon atom attached to four different atoms or groups of atoms

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36
Q

chromatogram

A

A visible record showing the result of separation of the components of a mixture by chromatography

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37
Q

cis-trans isomerism

A

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.

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38
Q

closed system

A

A system isolated from its surroundings

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39
Q

collision theory

A

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

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40
Q

concentration

A

The amount of solute, in moles, dissolved in 1 dm3 (1000cm3) of solution

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41
Q

condensation reaction

A

A reaction in which two small molecules react together to form a larger molecule with elimination of a small molecule such as water

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42
Q

coordinate bond

A

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

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43
Q

covalent bond

A

The strong electrostatic attraction between a shared pair of electron and the nuclei of the bonded atoms

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44
Q

dative covalent

A

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

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45
Q

dehydration

A

An elimination reaction in which water is removed from a saturated molecule to make an unsaturated molecule

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46
Q

delocalised electrons

A

Electrons that are shared between more than 2 atoms

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47
Q

desorption

A

Release of an adsorbed substance from a surface

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48
Q

dispole

A

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.

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49
Q

displacement reaction

A

A reaction in which a more reactive element displaces a less reactive element from an aqueous solution of its ions

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50
Q

displayed formula

A

A formula showing the relative positioning of all the atoms in a molecule and the bonds between them

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51
Q

disproportionation

A

A redox reaction in which the same element is both oxidised and reduced

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52
Q

dynamic equilibrium

A

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

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53
Q

E/Z isomerism

A

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.

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54
Q

electron configuration

A

A shorthand representation that shows how electrons occupy sub-shells in an atom

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55
Q

electronegativity

A

A measure of the attraction of a bonded atom for the pair of electrons in a covalent bond

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56
Q

electrophile

A

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

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57
Q

electrophilic reaction

A

The removal of a molecule from a saturated molecule to make an unsaturated molecule

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58
Q

elimination reaction

A

The removal of a molecule from a saturated molecule to make an unsaturated molecule

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59
Q

empirical formula

A

The formula that shows the simplest whole-number ratio of atoms of each element present in a compound

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60
Q

end point

A

The point in a titration where the indicator changes colour; the end point indicates when the reaction is just complete

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61
Q

endothermic reaction

A

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

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62
Q

enthalpy (H)

A

The heat content that is stored in a chemical system

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63
Q

enthalpy change

A

The difference between the enthalpy of the products and the enthalpy of the reactants

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64
Q

enthalpy cycle

A

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

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65
Q

ethalpy profile diagram

A

A diagram for a reaction to compares the enthalpy of the reactants with the enthalpy of the products

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66
Q

entropy

A

The used for the dispersal of energy an disorder within the chemicals making up the chemical system

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67
Q

equilibrium constant

A

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

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68
Q

equivalence point

A

The point in a titration at which the volume of one solution has reacted exactly with the volume of the second solution

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69
Q

esterification

A

A reaction in which a carboxylic acid reacts with an alcohol to form an ester and water

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70
Q

exothermic reaction

A

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

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71
Q

fingerprint region

A

an area of an infrared spectrum below 1500cm-1 that gives a characteristic pattern for different compounds

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72
Q

first electron affinity

A

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

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73
Q

first ionisation enerby

A

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

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74
Q

fractional distillation

A

The separation of components in a liquid mixture by their different boiling points into fractions with different compositions

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75
Q

fragment ions

A

Ions formed from the breakdown of the molecular ion in a mass spectrometer

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76
Q

fragmentation

A

The process in mass spectrometry that causes a positive ion to split into smaller pieces, one of which is a positive fragment ion.

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77
Q

functional group

A

The part of the organic molecule responsible for its chemical reactions

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78
Q

general formula

A

The simplest algebraic formula of a memmber of a homologous series. For example, the general forrmula of the alkanes is CnH2n+2+

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79
Q

giant covalent lattice

A

a 3 dimensional structure of atoms, bonded together by strong covalent bonds.

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80
Q

giant ionic lattice

A

A 3 diimensional structure of oppositely charged ions, bonded together by strong ionic bonds.

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81
Q

giant metallic lattice

A

A 3 dimensional structure of positive ions and delocalised electrons, bonded together by strong metallic bonds.

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82
Q

group

A

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.

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83
Q

half-life

A

The time taken for the concentration of a reactant to decrease by half

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84
Q

hess’s Law

A

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
Q

heterogeneous catalysis

A

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
Q

heterogeneous equilibrium

A

An equilibrium in which the species making up the reactants and products have different physical states

87
Q

heterolytic fission

A

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
Q

homogeneous catalysis

A

A reaction in which the catalyst and reactants are in the same physical state, which is more frequently the aqueous or gaseous state.

89
Q

homogeneous equilibrium

A

An equilibrium in which all the species making up the reactants and products have the same physical state.

90
Q

homologous series

A

A series of organic compounds with the same functional group but with each successive member differing by CH2.

91
Q

homolytic fission

A

The breaking of a covalent bond with one of the bonded electrons going to each atom, forming two radicals.

92
Q

hydrated

A

A crystalline compound containing water molecules

93
Q

hydrocarbon

A

A compound of hydrogen and carbon only

94
Q

hydrogen bond

A

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
Q

hydrolysis

A

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
Q

induced dipole-dipole interaction

A

attractive forces between induced dipoles in different molecules - also called London Forces

97
Q

infrared spectroscopy

A

An instrumentation method of analysis that identifes bonds from absorption of the infrared radiation of different wavelengths

98
Q

initial rate of reaction

A

the change in concentration of a reactant or product per unit time at the start of the reaction: t=0

99
Q

initiation

A

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
Q

intermediate

A

A species formed during a reaction that reacts further and is not present in the final products.

101
Q

intermolecular force

A

An attractive force between molecules. Intermolecular forces can be London forces, permanent dipole-dipole interactions or hydrogen bonding.

102
Q

ion

A

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
Q

ionic bonding

A

the electrostatic attraction between positive and negative ions.

104
Q

isotopes

A

Atoms of the same element with different numbers of neutrons and different masses.

105
Q

lattice enthalpy

A

The enthalpy change that accompanies the formation of one mole of an ionic compound from its gaseous ions under standard conditions.

106
Q

le Chatelier’s principle

A

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
Q

ligand

A

A molecule or ion that can donate a pair of electrons to the transition metal ion.

108
Q

ligand substitution

A

A reaction in which one or more ligands in a complex ion are replaced by different ligands

109
Q

limiting reagent

A

The reactant that is not in excess, which will be used up first and stop the reaction

110
Q

lone pair

A

An outer shell pair of electrons that is not involved in chemical bonding

111
Q

mass number

A

The sum of the number of protons and neutrons in the nucleus - also known as nucleon number

112
Q

metallic bond

A

The electrostatic attraction between positive metal ions and delocalised electrons

113
Q

mobile phase

A

The phase that moves in chromatography

114
Q

molar gas volume

A

The volume per mole of gas molecules at a stated temperature and pressure

115
Q

molar mass (M)

A

the mass per mole of a substance, in units off g mol-1

116
Q

mole

A

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
Q

molecular formula

A

A formula that shows the number and type of atoms of each element present in a molecule

118
Q

molecular ion

A

The positive ion formed in mass

119
Q

molecule

A

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
Q

monomer

A

A small molecule that combines with many other monomers to form a polymer

121
Q

neutralisation

A

A chemical reaction in which an acid and a base react together to produce a salt

122
Q

nomenclature

A

A system of naming compounds

123
Q

non-polar

A

with no charge separation across a bond or in a molecule

124
Q

nucleophile

A

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
Q

nucleophilic substitution

A

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
Q

order

A

The power to which the concentration of a reactant is raised in the rate equation

127
Q

overall order

A

The sum of the individual orders of reactants in the rate equation : m + n

128
Q

oxidation

A

Loss of electrons or an increase in oxidation number

129
Q

oxidation number

A

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
Q

oxidation state

A

The oxidation number

131
Q

oxidising agent

A

A reagent that oxidises (takes electrons from) another species.

132
Q

pie-bond

A

A bond formed by the sideways overlap of two p-orbitals, with the electron density above and the plane of the bonding atom

133
Q

partial dissociation

A

the splitting of some of a species in solution into aqueous ions

134
Q

pauling electronegativity value

A

A value assigned as a measure of the attraction of a bonded atom for the pair of electrons in a covalent bond

135
Q

period

A

A horizontal row of elements in the periodic table. Elements show trend in properties across a period

136
Q

periodicity

A

A repeating trend in properties of the elements across each period of the periodic table

137
Q

permanent dipole

A

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
Q

permanent dipole-dipole interaction

A

An attractive force between permanent dipoles in neighbouring polar molecules

139
Q

polar covalent bond

A

A bond with a permanent dipole, having positive and negative partial changes on the bonded atoms

140
Q

Polar molecule

A

A molecule with an overall dipole, having taken into account any dipoles across bonds and the shape of the molecule

141
Q

polyatomic ion

A

An ion containing more than 1 atom

142
Q

polymer

A

A large molecule formed from many thousands of repeat units of smaller molecules known as monomers

143
Q

position of equilibrium

A

The relative quantities of reactants and products, indicating the extent of a reversible reaction at equilibrium

144
Q

precipitation reaction

A

The formation of a solid from a solution during a chemical reaction. Precipitates are often formed when 2 aqueous solution are mixed together.

145
Q

primary

A

On a carbon atom at the end of a chain

146
Q

primary alcohol

A

An alcohol in which the OH group is attached to a carbon atom that is attached to two or three hydrogen atoms

147
Q

principal quantum number (n)

A

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
Q

propogation

A

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
Q

proton number

A

The number of protons in the nucleus of an atom; also known as atomic number

150
Q

radical

A

A species with an unpaired electron

151
Q

rate constant

A

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
Q

rate of reaction

A

The change in concentration of a reactant or a product in a given time.

153
Q

rate-determining step

A

The slowest step in the reaction mechanism of a multi-step reaction

154
Q

reaction mechanism

A

The sequence of bond breaking and bond-forming steps that shows the path taken by electrons during a reaction

155
Q

redox reaction

A

A reaction involving reduction and oxidation

156
Q

reducing agent

A

A reagent that reduces (adds electron to) another species

157
Q

reduction

A

Gain of electrons or a decrease in oxidation number

158
Q

reflux

A

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
Q

relative atomic mass

A

the weighted mean mass of an atom of an element compared with one-twelfth of the mass of an atom of carbon -12

160
Q

relative formula mass

A

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
Q

relative isotopic mass

A

The mass of an atom of an isotope compared with one-twelfth of the mass of an atom of carbon-12

162
Q

relative molecular mass

A

The weighted mean mass of a molecule of a compound compared with one-twelfth of the mass of an atom of carbon-12

163
Q

repeat unit

A

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
Q

retention time

A

In gas chromatography, the time for a component to pass from the column inlet to the detector

165
Q

reversible reaction

A

A reaction that takes place in both forward and reverse directions

166
Q

sigma bond

A

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
Q

salt

A

The product of a reaction in which the H- icons from the acid are replaced by metal or ammonium ions

168
Q

saturated

A

containing single bonds only

169
Q

saturated hydrocarbon

A

A hydrocarbon with single bonds only

170
Q

second electron affinity

A

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
Q

second ionisation energy

A

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
Q

secondary

A

On a carbon atom to which 2 carbon chains are attached.

173
Q

secondary alcohol

A

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
Q

shell

A

A group of atomic orbitals with the same principal quantum number, n . also known as a main energy level.

175
Q

shielding effect

A

The repulsioh between electrons in different inner shells. Shielding reduces the net attractive force between the positive nucleus on the outer shell electrons.

176
Q

simple molecular lattice

A

A three-dimensional structure of molecule, bonded together by weak intermolecular forces.

177
Q

skeletal formula

A

A simplified organic formula with hydrogen atoms removed from alkyl chains, leaving just a carbon skeleton and associated functional groups.

178
Q

specific heat capacity

A

The energy required to raise the temperature of 1g of a substance by 1C

179
Q

spectator ions

A

Ions that are present but take no part in a chemical reaction

180
Q

standard conditions

A

A pressure of 100kPa, a stated temperature, usually 298K (25C), and a concentration of 1 mol dm-3 (for reactions with aqueous solutions)

181
Q

standard enthalpy change of atomisation

A

The enthalpy change that takes place when one mole of gaseous atoms forms from the element in its standard state

182
Q

standard enthalpy change of combustion

A

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
Q

standard enthalpy change of formation

A

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
Q

standard enthalpy change of hydration

A

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
Q

standard enthalpy change of neutralisation

A

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
Q

standard enthalpy change of reaction

A

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
Q

standard enthalpy change of solution

A

The enthalpy change that takes place when one mole of a compound is completely dissolved in water under standard conditions.

188
Q

standard solution

A

A solution of known concentration

189
Q

standard state

A

The physical state of a substance under standard conditions of 100kPa and a stated temperature (usually 298K)

190
Q

stationary phase

A

The phase that does not move in chromatography

191
Q

stereoisomers

A

Compounds with the same structural formula but with a different arrangement of the atoms in space

192
Q

stoichiometry

A

The ratio of the amount, in moles, of each substance in a chemical equation (essentially the ratio of the balancing numbers)

193
Q

strong acid

A

An acid that dissociates completely in solution

194
Q

structural formula

A

A formula showing the minimal detail for the arrangement of atoms in a molecule

195
Q

structural isomers

A

Molecules with the same molecular formula but with different structural formulae

196
Q

sub-shell

A

A group of orbitals of the same type within a shell

197
Q

substitution reaction

A

A reaction in which an atom or group of atoms is replaced with a different atom or group of atoms

198
Q

surroundings

A

Everything that is not the chemical system

199
Q

system

A

The chemicals involved in the reaction

200
Q

termination

A

The step at the end of a radical substitution when two radicals combine to form a molecule

201
Q

tertiary alcohol

A

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
Q

theoretical yield

A

The yield resulting from complete conversion of reactants into products

203
Q

thermal decomposition

A

The breaking up of a chemical substance with heat into at least two chemical substances.

204
Q

titre

A

The volume added from the burette when the volume of one solution has exactly reacted with eth other solution

205
Q

transition element

A

A d-block element which forms an ion with an incomplete d-sub-shell

206
Q

unsaturated

A

containing a multiple carbon-carbon bond

207
Q

volatility

A

The ease at which a liquid turns into a gas. Volatility increases as boiling point decreases.

208
Q

water of crystallisation

A

Water molecules that are bonded into a crystalline structure of a compound

209
Q

weak acid

A

an acid that dissociates only partially in solution

Chemistry A level (6 decks)

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