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AAA - Chemistry A level > Glossary > Flashcards

Glossary Flashcards

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1
Q

Bronsted-Lowry Acid

A

A proton donor

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2
Q

Lewis Acid

A

An electron pair acceptor

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3
Q

Acid derivative

A

An organic compound related to a carboxylic acid of formula RCOZ, where z = -Cl, -NHR, -OR, or -OCOR.

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4
Q

Activation energy

A

The minimum energy that a particle needs in order to reach; the energy (enthalpy) difference between the reactants and the transition state.

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5
Q

Aldehyde

A

An organic compound with the general formula RCHO

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6
Q

Alkaline earth metals

A

The metals in group 2 of the periodic table

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7
Q

Alkane

A

A saturated hydrocarbon with only C-C and C-H single bonds, with the geral formula of C(n)H(2n+2)

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8
Q

Allotropes

A

Pure elements which can exist in different physical forms in which their atoms are arranged differently. For example, diamond, graphite and buckminster-fullerene are allotropes of carbon

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9
Q

Anaerobic respiration

A

The process by which energy is released and new compounds formed in living things in the absence of oxygen

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10
Q

Atom economy

A

This describes the efficiency of a chemical reaction by comparing the total number of atoms in the product with the total number of atoms in the starting materials. it is defined by
% atom economy = (mass of desired products)/(total mass of reactants)

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11
Q

Atomic orbital

A

A region of space around an atomic nucleus where there is a high probability of finding an electron

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12
Q

Avogadro constant

A

The total number of particles in a mole of substance. Also called the Avogadro number. It is numerically equal to 6.022 x 10^23

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13
Q

Bronsted-Lowry Base

A

A proton acceptor

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14
Q

Lewis Base

A

An electron pair donor

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15
Q

Base peak

A

The peak representing the ion of greatest abundance (the tallest peak) in a mass spectrum

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16
Q

Bond dissociation enthalpy

A

The Enthalpy change required to break a covalent bond with all species in the gaseous state

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17
Q

Buffer

A

A solution that resists change of pH when small amounts of acid or base are added or on dilution

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18
Q

Calorimeter

A

An instrument for measureing the heat changes that accompany chemical reactions

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19
Q

Carbocation

A

An organic ion in which one of the carbon atoms has a positive charge

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20
Q

Carbon-neutral

A

A process, or series of processes in which as much carbon dioxide is absorbed from the air as is given out.

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21
Q

Catalyst

A

A substance that alters the rate of a chemical reaction but is not used up in the reaction

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22
Q

Catalytic cracking

A

The breaking, with the aid of a catalyst, of long-chain alkane molecules(obtained from crude oil) into shorter chain hydrocarbons (some of which are alkenes)

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23
Q

Chelation

A

The process by which a multidentate ligand replaces a monodentate ligand in forming co-ordinate (dative) bonds to a transition metal ion

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24
Q

Chemical feedstock

A

The starting materials in an industrial chemical process

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25
Q

Chiral

A

Coming from the Greek for ‘handed’. A chiral molecule exists in two mirror image forms that are not superimposable

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26
Q

Chiral centre

A

An atom to which four different atoms or groups are bonded. The presence of such an atom causes the parent molecule to exist as a pair of nonsuperimposable mirror images

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27
Q

Co-ordinate bond

A

A covalent bond in which both the electrons come from one of the atoms forming the bond. (also called a dative bond.)

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28
Q

Co-ordination number

A

The number of ligand molecules bonded to a metal ion

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29
Q

Covalent bonding

A

Describes a chemical bond in a pair of electrons are shared between two atoms

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30
Q

Dative covalent bonding

A

Covalent bonding in which both the electrons in the bond come from one of the atoms in the bod (also known as Co-ordinate bonding

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31
Q

Delocalisation

A

Describes the process by which electrons are spread over several atoms and help bond them together

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32
Q

Delocalised

A

Describes elections that are spread over several atoms and help to bond them together

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33
Q

Dipole-dipole force

A

An intermolecular force that results from the attraction between molecules with permanent dipoles

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34
Q

Displacement reaction

A

A chemical reaction in which one atom or group of atoms replace another in a compound, for example,
Zn + CuO => ZnO + Cu

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35
Q

Displayed formula

A

The formula of a compound drawn out so that each atom and each bond is shown

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36
Q

Disproportionation

A

describes a redox reaction in which the oxidation number of some atoms of a particular element increases and that of of other atoms of the same element decreases

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37
Q

Dynamic equilibrium

A

A situation in which the composition of a constant concentration reaction mixture does not change because both forward and backward reactions are proceeding at the same rate

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38
Q

Electron density

A

The probability of electrons being found in a particular volume of space

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39
Q

Electron pair repulsion theory

A

A theory which explains the shapes of simple molecules by assuming that pairs of electrons around a central atom repel each other and thus take up positions as far away as possible from each other in space

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40
Q

Electronegativity

A

The power of an atom to attract the electrons in a covalent bond

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41
Q

Electrophile

A

An electron-deficient atom, ion or molecule that takes part in an organic reaction by attacking areas of high electron density in another reactant

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42
Q

Electrophilic addition

A

A reaction in which a carbon-carbon double bond is saturated, by the carbon-carbon double bond attacking an electrophile

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43
Q

Electrostatic forces

A

The forces of attraction and repulsion between electrically charged particles

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44
Q

Elimination

A

A reaction in which an atom or group of atoms is removed from a reactant

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45
Q

Empirical formula

A

The simplest whole number ration of atoms or each element in a compound

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46
Q

Enantiomer

A

one of a pair of nonsuperimposable mirror image isomers

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47
Q

Endothermic

A

Describes a reaction in which heat energy is taken in as the reactants change to products the temperature therefore drops

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48
Q

End point

A

The point in a titration when the volume of the reactant added just causes the colour of the indicator to change

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49
Q

Enthalpy change

A

A measure of heat energy given out or taken in when a chemical or physical change occurs at constant pressure

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50
Q

Enthalpy diagrams

A

Diagrams in which the enthalpies (energies) of the reactants and products of a chemical reaction are plotted on a vertical scale to show their relative levels

51
Q

Entropy

A

A numerical measure of disorder in a chemical system

52
Q

Equilibrium mixture

A

The mixture of reactants and products formed when a reversible reaction is allowed to proceed in a closed container until no further change occurs. The forward and backward reactions are still proceeding but at the same rate.

53
Q

Equivalence point

A

The point in a titration at which the reaction is just complete

54
Q

Exothermic

A

Describes a reaction in which heat energy is given out as the reactants change to products - the temperature therefore rises

55
Q

Fatty acid

A

A long-chain carboxylic acid

56
Q

Fingerprint region

A

The area of an infra-red spectrum below about 1500 cm^-1. it is caused by complex vibrations of the whole molecule and is characteristic of a particular molecule

57
Q

Fraction

A

A mixture of hydrocarbons collected over a particular range of boiling points during the fractional distillation of crude oil.

58
Q

Free radical

A

A chemical species with an unpaired electron - usually highly reactive

59
Q

Functional group

A

An atom or group of atoms in an organic molecule which is responsible for the characteristic reactions of that molecule

60
Q

Group

A

A vertical column of elements in the periodic table. The elements have similar properties because they have the same outer electron arrangement

61
Q

Half equation

A

An equation for a redox reaction which considers just on of the species involved and shows explicitly the electrons transferred to or from it

62
Q

Homologous series

A

A set of organic compounds with the same functional group. The compounds differ in the length of their hydrocarbon chains

63
Q

Hydration

A

A reaction in which water is added

64
Q

Hydrogen bonding

A

A type of intermolecular force in which a hydrogen atom (H^δ+) interacts with a more electronegative atom with a δ- charge

65
Q

Hydrolysis

A

A reaction of a compound or ion with water

66
Q

Incomplete combustion

A

A combustion reaction in which there is insufficient oxygen for all the carbon in the fuel to burn to carbon dioxide carbon monoxide and / or carbon (soot) are formed

67
Q

Inductive effect

A

the electronreleasing effect of alkyl groups such as CH3 or -C2H5

68
Q

Ionic bonding

A

Describes a chemical bond in which an electron or electrons are transferred from one atome to another, resulting in the formation of oppositely charged ions with electrostatic forces of attraction betwwen them

69
Q

Ionisation energy

A

The energy required to remove a mole of electrons from a mole of isolated gaseous atoms or ions

70
Q

Isome

A

One of two (or more) compounds with the same molecular formula but different arrangement of atoms in space

71
Q

Ketone

A

An organic compound with the general formula R2CO in which there is a C=O double bond not on the terminal carbon

72
Q

Lattice

A

A regular three-dimensional arrangement of atoms, ions or molecules

73
Q

Leaving group

A

In an organic substitution reaction, the leaving group is an atom or group of atoms that is effected from the starting material, normally taking with it an electron pair and forming a negative ion

74
Q

Ligand

A

An atom, ion or molecule that forms a co-ordinate (dative) bond with a transition metal ion using a lone pair of electrons

75
Q

Lone pair

A

A pair of electrons in the outer shell of an atom that is not involved in bonding

76
Q

Maxwell- Boltzmann distribution

A

The distribution of energies (and therefore speeds) of the molecules in a gas or liquid

77
Q

Mean bond enthalpy

A

The average value of the bond dissociation enthalpy for a give type of bond taken from a range of different compounds

78
Q

Metallic bonding

A

Describes a chemical bond in which outer electrons are delocalised within the lattice of metal ions

79
Q

Mole

A

A quantity of a substance that contains the Avogadro number (6.022 X 10^23) of particles (e.g. atoms, molecules or ions)

80
Q

Molecular formula

A

A Formula that tells us the actual number of atoms of each different element that make up a molecule of a compound

81
Q

Molecular ion

A

In mass spectrometry this is a molecule of a the sample which has been ionised but which has not broken up during its flight through the instrument

82
Q

Monomer

A

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

83
Q

Nucleons

A

Prons and neutrons - the sub-atomic particles found in the nuclei of atoms

84
Q

Nucleophile

A

A negative ion or molecule that is able to donate a pair of electrons and takes part in an organic reaction by attacking an electron-deficient area in another reactant

85
Q

Nucleophilic substitution

A

An organic reaction in which a molecule with a partially positively charged carbon atom is attacked by a reagent with a negative charge or partially negatively charged area (a nucleophile). It results in the replacement of one of the groups or atoms on the original molecule by the nucleophile

86
Q

Nucleus

A

The tiny, positively charged centre of an atom composed of protons and neutrons

87
Q

Optical isomer

A

Pairs of molecules that ate non superimposable mirror images

88
Q

Order of reaction

A

In the rate expression, this is the sum of the powers to which the concentrations of all the species involved in the reaction are raised.

89
Q

Oxidation

A

A reaction in which an atom or groups of atoms loses electrons

90
Q

Oxidation state

A

The number of electrons lost or gained by an atom in a compound compared to the individual atom. It forms the basis of a way of keeping track of redox (electron transfer) reactions. Also called oxidation number

91
Q

Oxidising agent

A

A reagent that oxidises (removes electrons from) another species

92
Q

Percentage yield

A

In a chemical reaction this is the actual amount of product produced divided by the theoretical amount (predicted from the chemical equation expressed as a percentage

93
Q

Period

A

A horizontal row of elements in the periodic table. There are trends in the properties of the eleents as we cross a period

94
Q

Periodicity

A

The regular recurrence of the properties of elements when they are arranged in atomic number order as in the periodic table

95
Q

pH

A

A scale for measuring acidity and alkalinity.

pH = -log[H+] in a solution

96
Q

Polar

A

Describes a molecule in which the charge is not symmetrically distributed so that one area is slightly positively charged and another slightly negatively charged

97
Q

Polarised

A

This describes an atom or ion where the distribution of charge around it is distorted from the spherical

98
Q

Positive inductive effect

A

Describes the tendency of some atoms or groups of atoms to release electrons via a covalent bond

99
Q

Proton number

A

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

100
Q

Protonated

A

Describes an atom, molecule or ion to which a proton (an H+ ion) has been added

101
Q

Racemate

A

A mixture of equal amounts of two optical isomers of a chiral compound. It is optically inactive

102
Q

Rate constant

A

The constant of proportionality in the rate expression

103
Q

Rate-determining step

A

The slowest step in the reaction mechanism. It governs the rate of the overall reaction

104
Q

Rate expression

A

A mathematical expression showing how the rate of a chemical reaction depends on the concentrations of various chemical species involved

105
Q

Reaction mechanism

A

The series of simple steps that lead from reactants to products in a chemical reaction

106
Q

Redox reaction

A

Short for reduction-oxidation reaction, it describes reactions in which electrons are transferred from one species to another

107
Q

Reducing agent

A

A reagent that reduces (adds electrons to) another species

108
Q

reduction

A

A reactions in which an atom or group of atoms gain electrons

109
Q

Ar / Mr

A

the average mass of a particle / a twelth of the mass of a carbon 12 atom

110
Q

Saturated hydrocarbon

A

A compound containing only hydrogen and carbon with only C-C and C-H single bonds, i.e. one to which no more hydrogen can be added

111
Q

Specific heat capacity

A

The amount of heat needed to raise the temperature of 1g of substance by 1 K

112
Q

Spectator ions

A

Ions that are unchanged during a chemical reaction, that is, they take no part in the reaction

113
Q

Standard molar enthalpy change of combustion

A

The enthalpy change when 1 mole of a substance is completely burned in oxygen with all reactants and products in their standard states (298 K and 100KPa)

114
Q

Standard molar enthalpy change of formation

A

The enthalpy change when 1 mole of substance is formed from its elements with all reactants and products in their standard states (298 K and 100 KPa)

115
Q

Stereoisomer

A

Isomers with the same molecular formula and the same structure, but a different position of atoms in space

116
Q

Stoichiometry

A

Describes the simple whole number ratios in which chemical species react

117
Q

Strong acid

A

An acid that is fully dissociated into ions in solution

118
Q

Strong nuclear force

A

The forces that holds protons and neutrons together within the nucleus of the atom

119
Q

Structural formula

A

A way of writing the formula of an organic compound in which bonds are not shown but each carbon atom is written separately with the atoms or groups of atoms attached to it

120
Q

Structural isomer

A

Isomers with the same molecular formula but a different structure

121
Q

Thermochemical cycle

A

A sequence of chemical reactions (with their enthalpy changes) that convert a reactant into a product. The total enthalpy change of the sequence of reactions will be the same as that for the conversion of the reactant to the product directly (or by any other route (as used in Hess cycles))

122
Q

Triglyceride

A

An ester formed between glycerol (propane-1,2,3-triol) and three fatty acid molecules

123
Q

van der Waals force

A

A type of intermolecular force of attraction that is caused by instantaneous dipoles and acts between all atoms and molecules

124
Q

Weak acid

A

An acid that is only slightly dissociated into ions in solution. They will also have a Ka value

AAA - Chemistry A level (7 decks)

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