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Alevel Chemistry > Year 1 definitions > Flashcards

Year 1 definitions Flashcards

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1
Q

Isotope

A

Atoms of same element with different numbers of neutrons

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2
Q

Atomic (proton) number

A

Number of protons in the nucleus of an atom

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3
Q

Mass (nucleon) number

A

Number of particles (protons + neutrons) in the nucleus

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4
Q

Ion

A

Positively or negatively charge atom or (covalently bonded) group of atoms (a molecular ion)

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5
Q

Relative Isotopic mass

A

Mass of an atom of an isotope compared with 1/12 the mass of an atom of carbon-12.

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6
Q

Relative Atomic Mass (Ar)

A

Weighted mean mass of an atom of an element compared with 1/12 the mass of an atom of carbon-12.

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7
Q

Relative Molecular Mass (Mr)

A

Weighted mean mass of an atom of a molecule compared with 1/12 the mass of an atom of carbon-12.

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8
Q

Relative Formula Mass

A

Weighted mean mass of a formula unit compared with 1/12 the mass of an atom of carbon-12.

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9
Q

Avogadro Constant

A

The number of atoms per mole (6.02 X 1023 mol-1)

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10
Q

Mole

A

The amount of any substance containing as many particles as there are carbon atoms in exactly 12g of the carbon-12 isotope.

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11
Q

Molar Mass (Mr)

A

The mass per mole of a substance. (g mol-1)

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12
Q

Empirical Formula

A

The simplest whole-number ratio of atoms of each element present in a compound.

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13
Q

Molecule

A

A small group of atoms held together by covalent bonds.

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14
Q

Molecular Formula

A

The actual number of atoms of each element in a molecule.

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15
Q

Molar volume

A

Volume per mole of a gas (dm3mol-1)

At RT&P Molar Volume =24 dm3mol-1

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16
Q

Concentration

A

The amount of solute (mol) dissolved in 1dm3 of solution

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17
Q

Standard Solution

A

A solution of a known concentration

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18
Q

Species

A

Any type of particle that takes place in a chemical reaction.

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19
Q

Stoichiometry

A

The molar relationship between relative quantities of substance taking part in a reaction.

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20
Q

Acid

A

A species that is a proton donor.

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21
Q

Base

A

A species that is a proton acceptor.

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22
Q

Alkali

A

A base that dissolves in water to form hydroxide ions.

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23
Q

Salt

A

Any chemical compound formed from an acid when H+ is replaced by a metal or other positive ion.

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24
Q

Cation

A

A positively charged ion

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25
Q

Anion

A

A negatively charged ion

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26
Q

Hydrated

A

Crystalline compound containing water molecules.

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27
Q

Anhydrous

A

A substance that contains no water molecules.

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28
Q

Water of Crystallisation

A

Water molecules that form an essential part of the crystalline structure of a compound.

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29
Q

Oxidation Number

A

A measure of the number of electrons that an atom uses to bond with atoms of another element.

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30
Q

Oxidation

A

Loss of electrons OR increase in oxidation number

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31
Q

Reduction

A

Gain of electrons OR decrease in oxidation number

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32
Q

Redox

A

A reaction in which both reduction and oxidation take place.

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33
Q

Reducing Agent

A

A reagent that reduces (adds electrons to) another species.

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34
Q

Oxidising agent

A

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

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35
Q

First ionisation energy

A

The energy required to remove one electron from each atom (of an element) in one mole of gaseous atoms from one mole of gaseous 1+ ions

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36
Q

Electron shielding

A

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

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37
Q

Successive ionisation energies

A

The measure of energy required to remove each electron in turn. Eg second ionisation energy of an element is the energy required to remove an electron from each ion in one mole of gaseous 1+ ions to form one mole of gaseous 2+ ions.

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38
Q

Shell

A

A groups of atomic orbitals with the same principal number, n.

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39
Q

Principal quantum number

A

A number representing the relative overall energy of each orbital, which increase with distance from the nucleus.

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40
Q

Atomic orbital

A

A region within an atom that can hold up to 2 electrons, with opposite spins.

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41
Q

Sub-shell

A

A group of the same type of atomic orbitals (s, p, d, or f) within a shell

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42
Q

Electron configuration

A

The arrangement of electrons in an atom.

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43
Q

Compound

A

A substance formed from 2 or more chemically bonded elements in a fixed ratio.

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44
Q

Ionic Bond

A

The electrostatic attraction between oppositely charged ions.

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45
Q

Giant ionic lattice

A

A 3-D structure of oppositely charged ions, held together by strong ionic bonds.

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46
Q

Group

A

A vertical column in the Periodic Table, with elements of similar properties and the same number of outer shell electrons.

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47
Q

Covalent Bond

A

A bond formed by a shared pair of electrons.

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48
Q

Lone pair

A

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

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49
Q

Dative Covalent Bond (Coordinate)

A

A shared pair of electrons which has been provided by one of the bonding atoms only.

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50
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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51
Q

Permanent dipole

A

A small charge difference across a bond that results from the difference in electronegativity of the bonded atoms

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52
Q

Polar covalent bond

A

A permanent dipole.

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53
Q

Intermolecular Force

A

An attractive force between neighbouring molecules.

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54
Q

Permanent dipole-dipole

A

A weak attractive force between permanent dipole in neighbouring molecules.

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55
Q

Van der Waal’s forces

A

Attractive forces between induced dipoles in neighbouring molecules.

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56
Q

Hydrogen bond

A

A strong dipole-dipole attraction between an electron deficient hydrogen in one molecule and a lone pair of electrons on a highly electronegative atom in a different molecule.

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57
Q

Metallic bonding

A

Electrostatic attraction between positive metal ions and delocalised electrons

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58
Q

Giant Metallic lattice

A

3-D Structure of positive ions and delocalised electrons bonded together by strong metallic bonds

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59
Q

Simple molecular lattice

A

3-D structure of molecules bonded together by weak intermolecular forces.

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60
Q

Giant Molecular lattice

A

3-D structure of atoms, bonded together by strong covalent bonds.

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61
Q

Delocalised electrons

A

Electrons that are shared between more than 2 atoms

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62
Q

Periodicity

A

The regular variation of elements with atomic umber and position in the periodic table.

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63
Q

Thermal decomposition

A

breaking of chemical substance with heat into at least 2 chemical substances.

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64
Q

Displacement reaction

A

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

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65
Q

Disproportionation

A

The oxidation and reduction of the same element in a redox reaction.

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66
Q

Precipitation reaction

A

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

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67
Q

Nomenclature

A

Is a system for naming compounds

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68
Q

Unsaturated Hydrocarbon

A

A hydrocarbon containing at least one carbon-carbon double bond.

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69
Q

Homologous series

A

Is an organic series with the same functional group but with each member differing by CH2

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70
Q

Functional Group

A

Is part of an organic molecule responsible for its chemical properties

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71
Q

Alkane

A

The homologous series without double bonds and the general formula - cnh2n+2

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72
Q

Alkene

A

The homologous series with a double bond and the general formula - cnh2n

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73
Q

Displayed formula

A

Shows the relative positions of all atoms in a molecule with bonds between them

74
Q

Structural formula

A

Shows minimal detail of the arrangement of atoms in a molecule

75
Q

Skeletal Formula

A

Formula with hydrogen’s removed and only the bonds between carbon atoms show, not the atoms themselves.

76
Q

Structural Isomers

A

Isomers with the same molecular formula but a different structural formula

77
Q

Positional isomerism

A

A type of structural isomerism. When a functional group is on a different numbered carbon,

78
Q

Chain isomerism

A

A type of structural isomerism. When branches occur in a chain.

79
Q

Stereo isomers

A

Isomers with the same structural formula but a different arrangement in space around a double bond.

80
Q

E/Z isomerism

A

A type of stereo isomerism. Double bond stops rotation and different groups on the carbons of this double bond

81
Q

Homolytic Fission

A

When a covalent bond breaks giving an electron to each atom creating 2 radicals.

82
Q

Hetrolytic fission

A

When a covalent bond breaks and give both electrons to 1 atom forming 1 positive and 1 negative ion.

83
Q

Radical

A

A species with an unpaired electron

84
Q

Nucleophile

A

(nucleus loving) An electron pair Donator.

85
Q

Electrophile

A

(electron loving) an electron pair Acceptor

86
Q

Addition reaction

A

When a species ADDS to another species. Requires a double bond

87
Q

Substitution reaction

A

When a species REPLACES another species in a reaction.

88
Q

Elimination reaction

A

When a molecule is REMOVED from another molecule forming a double bond

89
Q

Nucleophile substitution

A

When a nucleophile replaces a halogen.

90
Q

Free radical Substitution

A

When a halogen replaces a H in a reaction. 3 steps I,P,T

91
Q

Electrophilic Addition

A

When a species ADDS across a double bond.

92
Q

Fractional distillation

A

When crude oil is split into its components by their boiling points

93
Q

Cracking

A

When a long chain alkane are split into a shorter alkane and an alkene

94
Q

Combustion

A

When a compound is burnt completely in oxygen to form carbon dioxide and water

95
Q

Incomplete combustion

A

When a compound is burnt in oxygen to form carbon, or carbon monoxide, and water.

96
Q

Pi bond

A

Formed by the sideways overlap of adjacent p orbitals - always use diagram.

97
Q

Polymer

A

Long chain of monomers

98
Q

Monomer

A

Small monomer, usually a alkene, used to build up a polymer

99
Q

Volatility

A

Is the ease that a liquid turns into a gas. Volatility increases as boiling point decreases.

100
Q

Oxidation

A

When oxygen is added to a molecule

101
Q

Oxidising agent

A

Acidified potassium dichromate

102
Q

Reflux

A

Used to make primary alcohols into carboxylic acids or secondary into ketones

103
Q

Distillation

A

Used to make primary alcohols into aldehydes or secondary into ketones.

104
Q

Ester

A

Formed when an alcohol and carboxylic acid react. -(C=O)-O-(CH2)-

105
Q

Esterification

A

Is the reaction between an alcohol with a carboxylic acid to produce ester and water.

106
Q

Dehydration

A

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

107
Q

Hydrolysis

A

Is the reaction with water or aqueous hydroxide ions that breaks a chemical bond into two compounds.

108
Q

Percentage yield

A

Found by moles product/moles of reactant x100.

109
Q

Atom economy

A

Mr of desired product/Mr of all products x100

110
Q

IR spectroscopy

A

Shows the absorption of IR radiation by bonds to show what bonds are present in a sample

111
Q

Mass spectrometry

A

Shows the mass/charge for fragments of a molecule

112
Q

MS fragment

A

A piece of the molecule broke in MS. Allows us to piece together the starting molecule.

113
Q

Enthalpy, H

A

The heat energy stored in a chemical system

114
Q

Exothermic

A

When the enthalpy is smaller at then end of a reaction than at the beginning. Resulting in heat loss. Deltah -ve.

115
Q

Endothermic

A

When the enthalpy is greater at then end of a reaction than at the beginning. Resulting in heat being taken in. Deltah +ve.

116
Q

Activation energy

A

Minimum energy required to start a reaction by the breaking of bonds.

117
Q

Enthalpy profile diagram

A

Shows the enthalpy of the reactants and products along with the activation energy and enthalpy change.

118
Q

Standard conditions

A

Pressure of 100kpa and Temperature of 298K. In solution concentration of 1M.

119
Q

Standard state

A

The state we find a substance in under standard conditions.

120
Q

Standard enthalpy change of reaction

A

Is the enthalpy change that accompanies the moles given in a balanced equation are reacted under standard conditions and in standard states

121
Q

Standard enthalpy change of combustion

A

Is the enthalpy change when one mol of reactant is burned completely in oxygen under standard conditions

122
Q

Standard enthalpy change of formation

A

Is the enthalpy change when 1 mol of product is formed from its constituent elements in standard states under standard conditions.

123
Q

Specific heat capacity, C

A

Energy required to heat 1g of substance by 1K.

124
Q

Bond enthalpy

A

Is the enthalpy change when 1 mol of given bonds is broken by homolytic fission in a gaseous state.

125
Q

Hess’ Law

A

“if a reaction can take place by more than 1 route and the initial and final conditions are the same, the total enthalpy change is the same for each route.”

126
Q

Rate of reaction

A

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

127
Q

Catalyst

A

A species than lowers the activation energy of a reaction by providing an alternate route but is not used itself.

128
Q

Boltzmann distribution

A

Is the distribution of energies of molecules within a sample at a given temperature.

129
Q

Dynamic equilibrium

A

An equilibrium in a closed system where the rate of forward reaction equals that of the reverse reaction leaving constant concentrations of products and reactants.

130
Q

Le chatelier’s principle

A

When a change is imposed on a system in dynamic equilibrium the position of the equilibrium will change to minimise the change.

131
Q

Greenhouse effect

A

The process by which absorption and subsequent emission of ir radiation by atmospheric gasses warms the lower atmosphere and the planet’s surface

132
Q

Troposphere

A

Lowest layer of earths atmosphere surface to between 7km & 20km

133
Q

Stratosphere

A

Second layer of atmosphere contains ozone layer. From troposphere to ~50km

134
Q

Adsorption

A

Process by which a gas, liquid or solute is held to a solid surface - such as in a catalytic convertor.

135
Q

Delocalised electrons

A

shared between more than two atoms.

136
Q

Curly arrow

A

a symbol used to show the movement of an electron pair.

137
Q

Stem

A

the longest carbon chain present in an organic molecule.

138
Q

Redox reaction

A

one where both reduction and oxidation takes place.

139
Q

Nucleophile

A

a species which is attracted to electron deficient centres, where it donates an electron pair to form a new covalent bond.

140
Q

Esterification

A

the reaction between a carboxylic acid and an alcohol to form a ester and water.

141
Q

Hydrolysis

A

a reaction with water or hydroxide that breaks a chemical compound into two compounds.

142
Q

Peptide

A

a compound made of amino acids linked by peptide bonds.

143
Q

Zwitterion

A

a dipolar ion of an amino acid that is formed by the donation of a hydrogen ion from the carbonyl group to the amino group. Both charges are present but there is no overall charge.

144
Q

Isoelectric point

A

the pH value at which the amino acid exist as a zwitterion.

145
Q

Condensation reaction

A

one where two molecules react to from a large molecule with the elimination of a small molecule such as water.

146
Q

Stereoisomerism

A

species with the same structural formula but a different arrange moment in space.

147
Q

Chiral carbon

A

a carbon bonded to 4 different atoms or group of atoms

148
Q

Optical isomerism / enantiomers

A

stereoisomers that are non-superimposable mirror images of each other

149
Q

Biodegradable polymer

A

polymer that breaks down completely into carbon dioxide and water

150
Q

Degradable polymer

A

polymer that breaks down into smaller fragments when exposed to light, heat or moisture

151
Q

Phase

A

a physically distinctive form of a substance, such as the solid, liquid or gaseous states of ordinary matter

152
Q

Mobile phase

A

the phase that moves in chromatography

153
Q

Stationary phase

A

the phase that doesn’t move in chromatography.

154
Q

Chromatogram

A

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

155
Q

Rf

A

distance moved by component/distance moved by solvent front

156
Q

Retention time

A

(in gas chromatography) - the time for a component to pass from the column inlet to the detector.

157
Q

Chemical shift

A

a scale that compares the frequency of an NMR absorption with the frequency of the reference peak of TMS at δ = 0ppm

158
Q

Rate of reaction

A

the change ion concentration of a species per unit time

159
Q

Initial rate of reaction

A

change of concentration of a species per unit time, at the start of a reaction.

160
Q

Half life

A

(of a reactant) - the time taken for the concentration of the reactant to reduce by half.

161
Q

Reaction mechanism

A

series of steps that make up the overall reaction

162
Q

Rate determining step

A

slowest step in the a multi- step reaction mechanism

163
Q

Intermediate

A

a species formed in one step of a multi- step reaction that is used up in the next step so is not seen as a product or reactant in the overall reaction

164
Q

Equilibrium law

A

aA +bB cC + dD

Kc= [C]c[D]d / [A]a[B]b

165
Q

dynamic equilibrium

A

exist in a closed system when the rate of reaction is equal to the rate of reverse reaction

166
Q

Homogeneous equilibrium

A

an equilibrium where all species are in the same physical state

167
Q

Neutralistaion

A

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

168
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

169
Q

Enthalpy change of formation

A

enthalpy change when 1 mole of compound is formed from its elements under standard conditions

170
Q

Enthalpy change of atomisation

A

the enthalpy change that takes place when 1 ole of gaseous atoms forms from the elements in standard states

171
Q

Ionisation energy

A

energy required to remove 1 mole of electrons from 1 mole of gaseous atoms to form 1 mole of 1+ ions

172
Q

Standard enthalpy change of solution

A

enthalpy change when 1 mole of compound is completely dissolved in water under standard conditions

173
Q

Standard enthalpy change of hydration

A

enthalpy change when 1 mole of isolated gaseous ions is dissolved in water forming 1 mole of aqueous ions under standard conditions

174
Q

Entropy

A

the quantum measure of degree of disorder in a system

175
Q

(Gibbs) Free energy change

A

ΔG is the balance between enthalpy and entropy and temperature for a process.

ΔG = ΔH – TΔS. For a process to take place ΔG <0.

176
Q

Standard electrode potential

A

of a half cell, Eθ, is the emf of a half cell when compared to the standard hydrogen half cell, measured under standard conditions.

177
Q

Transition element

A

an element in the d – block of the periodic table that forms an ion with an incomplete d sub-shell.

178
Q

Complex ion

A

a transition metal ion bonded to one or more ligands by coordinate (dative covalent) bonds

179
Q

Ligand

A

a molecule or ion that can donate an electron pair to a metal ion to form a coordinate bond

180
Q

Coordination number

A

the number of coordinate bonds a metal ion can have with its ligands

181
Q

Ligand substitution

A

a reaction in which one ligand in a complex ion is replaced by another ligand

182
Q

Stability constant

A

k stab =is the equilibrium existing between a transition metal ion surrounded by water ligands and the complex formed when the same ion has undergone ligand substitution

Alevel Chemistry (8 decks)

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