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A - Level Chemistry > Definitions > Flashcards

Definitions Flashcards

1
Q

Define the atomic number

A

The number of protons

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2
Q

Define an isotope

A

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

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3
Q

Define the mass number (on periodic table)

A

The number of protons + the number of neutrons

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4
Q

Define an ion.

A

A charged atom

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5
Q

Define a cation

A

A positive ion - atoms with fewer electrons than protons

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6
Q

Define an anion

A

A negative ion - atoms with more electrons than protons

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7
Q

Define the relative isotopic mass

A

The mass of an isotope relative to 1/12th of the mass of an atom of carbon-12.

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8
Q

Define the relative atomic mass Ar

A

The weighted mean mass of an atom of an element relative to 1/12th of the mass of an atom of carbon-12.

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9
Q

Define a binary compound

A

Contains 2 elements only

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10
Q

Define a polyatomic ion

A

An ion that contains more than 1 element bonded together

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11
Q

Define a diatomic molecule

A

2 of the same atoms bonded together e.g. O2,Cl2

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12
Q

Define the formula unit

A

In ionic compounds, the formula worked out from the ionic charges that are used in equations

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13
Q

Define avogadros constant

A

6.02 x 10^23 mol^-1

The number of particles in each mole of carbon-12

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14
Q

Define molar mass

A

The mass per mole of a substance in units of g mol^-1

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15
Q

Define the molecular formula

A

The number of atoms of each element in a molecule

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16
Q

Define the empirical formula

A

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

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17
Q

Define the relative molecular mass Mr

A

Compares the mass of a molecule with the mass of an atom of carbon-12

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18
Q

Define the relative formula mass

A

Compares the mass of a formula unit with the mass of an atom of carbon-12

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19
Q

Define hydrated

A

A crystalline compound containing water molecules

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20
Q

Define the water of crystallisation

A

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

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21
Q

Define anhydrous

A

Containing no water molecules

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22
Q

Define standard solution

A

A solution of known concentration

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23
Q

Define molar gas volume

A

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

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24
Q

Define limiting reagent

A

The reactant that is not in excess and is used up first and stops the reaction.

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25
Q

Define atom economy

A

A measure of how well atoms have been utilised.

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26
Q

Define a strong acid

A

An acid that completely dissociates in aq to release H+

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27
Q

Define a weak acid

A

An acid that partially dissociates in aq to release H+

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28
Q

Define a salt

A

Product of reaction in which H+ from acid are replaced by metal or ammonium ions.

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29
Q

Define a base

A

Insoluble compound that neutralises an acid to form a salt.

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30
Q

Define an alkali

A

A soluble base that dissociates in aq to release OH-

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31
Q

Define titration

A

A technique use dot accurately measure the volume of one solution that reacts exactly with another solution.

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32
Q

Define a redox reaction

A

A reaction involving reduction and oxidation

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33
Q

Define principal quantum number

A

The shell number or energy level number

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34
Q

Define an atomic orbital

A

A region around the nucleus that can hold up to 2 electrons with opposite spins.

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35
Q

Define sub-shell

A

A group of orbitals of the same type within a shell

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36
Q

Define an ionic bond

A

The electrostatic attraction between positive (anions) and negative ions (cations).

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37
Q

Define a covalent bond

A

The head on strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms.

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38
Q

Define lone pair of electrons

A

Paired electrons that are not shared

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39
Q

Define a dative covalent bond (coordinate bond)

A

A covalent bond in which the shared pair of electrons has been supplied by one of the bonding atoms only.

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40
Q

Define electronegativity

A

The attraction of a bonded atom for the shared pair of electrons in a covalent bond.

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41
Q

Define periodicity

A

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

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42
Q

Define 1st ionisation energy

A

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

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43
Q

Define shielding effect

A

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

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44
Q

Define 2nd ionisation energy

A

The energy required to remove 1 electron from each ion in one mole of gaseous 1+ ions of an element to form 1 mole of gaseous 2+ ions.

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45
Q

Define metallic bonding

A

The strong electrostatic attraction between positive ions and delocalised electrons.

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46
Q

Define a reducing agent

A

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

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47
Q

Define a disproportionation reaction

A

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

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48
Q

Define enthalpy

A

A measure of heat energy in a chemical system

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49
Q

Define the law of conservation of energy

A

Energy cannot be created/destroyed

50
Q

Define exothermic reaction

A

A reaction in which the enthalpy of products is smaller than the enthalpy of reactants, resulting in heat loss to the surroundings

51
Q

Define 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.

52
Q

Define activation energy

A

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

53
Q

Define standard pressure

A

100 kPa

54
Q

Define standard temperature

A

298K (25*C)

55
Q

Define standard concentration

A

1 mol dm-3

56
Q

Define standard state

A

The physical state of a substance under standard conditions.

57
Q

Define standard enthalpy change of reaction

A

The enthalpy change that accompanies a reaction in the molar quantities shown in a chemical equation under standard conditions, with all reactants and products in their standard states.

58
Q

Define standard enthalpy change of formation

A

The enthalpy change that takes place when 1 mole of a compound is formed from its elements under standard conditions with all reactant and products in their standard states.

59
Q

Define standard enthalpy change of combustion

A

The enthalpy change that takes place when 1 mole of a substance reacts completely with oxygen under standard conditions, with all reactants and products in their standard states.

60
Q

Define standard enthalpy change of neutralisation

A

The energy change that accompanies the reaction of an acid by a base to form 1 mole of H2O(l), under standard conditions, with all reactants and products in their standard states.

61
Q

Define specific heat capacity

A

The energy required to raise the temp of 1g of a substance by 1K.

62
Q

Define average bond enthalpy

A

Energy required to break 1 mole of a specified type of bond in a gaseous molecule.

63
Q

Define Hess’ law

A

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

64
Q

Define rate of reaction

A

Change in concentration of a reactant or a product in a given time.

65
Q

Define a catalyst

A

A substance that changes the rate of a chemical reaction without undergoing any permanent change itself.

66
Q

Define homogenous catalyst

A

A reaction in which the catalyst and reactants are in the same physical state, which’s most frequently the aqueous or gaseous state.

67
Q

Define heterogeneous catalysts

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.

68
Q

Define position of equilibrium

A

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

69
Q

Define le chateliers principle

A

When a system in equilibrium is subjected to an external change the system readjusts itself to minimise the effect of that change.

70
Q

Define Kc

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.

71
Q

Define hydrocarbon

A

Compound containing C and H only.

72
Q

Define saturated

A

Single bonds only

73
Q

Define unsaturated

A

Contains C-C multiple bonds

74
Q

Define homologous series

A

A family of compounds with similar chemical properties whose successive members differ by the addition of a -CH2- group.

75
Q

Define functional group

A

The part of the organic molecule that’s largely responsible for the molecule’s chemical properties.

76
Q

Define aliphatic

A

C atoms are joined to each other in unbranched (straight) or branched chains, or non-aromatic rings

77
Q

Define alicyclic

A

C atoms are joined to each other in ring (cyclic) structures, with or without branches

78
Q

Define aromatic

A

Some or all of the C atoms are found in a benzene ring

79
Q

Define molecular formula

A

Shows number and type of atoms of each element present in a molecule.

80
Q

Define empirical formula

A

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

81
Q

Define general formula

A

The simplest algebraic formula for any member of a homologous series.

82
Q

Define structural isomer

A

Compounds with the same molecular formula but different structural formula.

83
Q

Define radical

A

Atom/groups of atoms with an unpaired electron

84
Q

Define homolytic fission

A

CB breaks, each of bonded atoms take 1 of shared pair of electrons from the bond.

85
Q

Define heterolytic fission

A

CB breaks, 1 of bonded atoms takes both of electrons from the bond. To form neg and pos ions.

86
Q

Define curly arrow

A

Show movement of electron pairs when bonds are being broken or made.

87
Q

Define fish arrow hook

A

Movement of a single unpaired electron

88
Q

Define addition reaction

A

2 reactants join together to form 1 product

89
Q

Define substitution reaction

A

Atom/group of atoms is replaced by a diff atom or group of atoms.

90
Q

Define elimination reaction

A

Involves removal of small molecule from a larger one

91
Q

Define sigma Bond

A

The overlap of 2 atomic orbitals, 1 from each bonding atom directly between bonding atoms

92
Q

Define pi-bond

A

Sideways overlap of 2 adjacent p-orbitals above and below bonding C atoms, 1 from each C atom of double bond.

93
Q

Define stereoisomer

A

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

94
Q

Define electrophiles

A

Electron pair acceptor

95
Q

Define carbocation

A

Ion that consists a pos charged C atom

96
Q

Define polymer

A

Large molecule formed from many thousands of repeat units of smaller molecules known as monomers.

97
Q

Define addition polymerisation

A

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

98
Q

Define monomer

A

Small molecule that combines with many other monomers to form a polymer.

99
Q

Define repeat unit

A

The specific arrangement of atoms in polymer molecule that repeats over and over again.

100
Q

Define dehydration

A

An elimination reaction in which H2O id removed from a saturated molecule to make an unsaturated molecule.

101
Q

Define nucleophile

A

Electron pair donor

102
Q

Define hydrolysis

A

Reaction with H2O that breaks a chemical compound into 2 compound, the H and OH in a water molecule becomes incorporated into the 2 compounds

103
Q

Define molecular ion

A

Pos ion formed in mass spectrometry when a molecule loses an electron

104
Q

Define M + 1 peak

A

The very small peak one unit after the M+ peak which exists because 1.1% of C is present as C-13 isotope.

105
Q

Define fragmentation

A

Process in mass spectrometry that causes a pos ion to split into smaller pieces, 1 of which is a pos fragment ion.

106
Q

Define fragment ion

A

Ions formed from breakdown of molecular ion in a mass spectrometer

107
Q

Define finger print region

A

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

108
Q

Define half-life

A

Time taken for conc of reactant to decrease by half

109
Q

Define rate-determining step

A

Slowest step in reaction mechanism of a multi-step reaction

110
Q

Define homogeneous equilibrium

A

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

111
Q

Define heterogeneous equilibrium

A

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

112
Q

Define partial pressure

A

The contribution that the gas makes towards total pressure.

113
Q

Define bronsted Lowry acid

A

Proton donor

114
Q

Define bronsted Lowry base

A

Proton acceptor

115
Q

Define conjugate acid-base pairs

A
116
Q

Define (mono-,di-,tri-) -basic acids

A
117
Q

Define acid dissociation constant Ka

A
118
Q

Define ionic product of water

A
119
Q

Define a buffer solution

A
120
Q

Define equivalence point

A
121
Q

Define end point

A
122
Q

Define esterification

A

Reaction of an alcohol with carboxylic acid to Form an ester

A - Level Chemistry (11 decks)

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