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Chemistry A LEVEL > Key Words > Flashcards

Key Words Flashcards

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1
Q

Mole

A

The amount of substance containing as many particles As there are carbon atoms in exactly 12 g of carbon 12

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2
Q

Molar mass

A

The mass in grams per mole of a substance

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3
Q

An acid is

A

A proton donor that dissociates its ions

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4
Q

A strong acid

A

Completely dissociates it’s ions I’m aqueous solution

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5
Q

A weak acid

A

Partially dissociates into its ions in aqueous solution

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6
Q

A base

A

A proton acceptor

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7
Q

An alkali is

A

A base that dissolves In water and releases 0H ions in aqueous solution

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8
Q

A salt is produced when

A

The H Ion of an acid is replaced by a metal iOn or NH4

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9
Q

Ionic bonding

A

The electrostatic attraction between opposite Lee charged ions

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10
Q

Covalent bonding

A

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

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11
Q

Dative covalent bonding

A

Strong electrostatic attraction between a shared pair of electrons and the nuclei of the atoms are five but where only one of the atoms supplies both of the electrons shared

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12
Q

Average bond enthalpy

A

Can be used as a measurement of covalent bond strength

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13
Q

Shapes of molecules (four)

A

Electron pairs repel each other to get as far apart as possible
Always covalent bonding
Lone pairs repel more strongly than bonding pairs
Shape is determined by the number and type of electron pairs around the central atom

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14
Q

Electronegativity

A

The ability of an atom to attract the bonding electrons towards itself in a covalent bond

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15
Q

Carbon chain length

4

A

As the C chain length increases the boiling point increases

Because there is more surface contact between molecules

So there are more induced dipole dipole interactions between the molecules

Which need more energy to overcome

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16
Q

Branching (3)

A

A branched isomer has a lower boiling point

In a more branched alkane the is les surface contact between molecules leading to fewer induced dipole dipole interactions

Which need less energy to break the weaker induced dipole dipole between molecules

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17
Q

Reacting volume of gases

A

1 mole of any gas occupies a volume of 24dm^3

At RTP

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18
Q

Ideal gas equation

A

pV=nRT

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19
Q

Empirical formula

A

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

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20
Q

Molecular formula

A

The actual number and type of atoms of each element in a molecule

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21
Q

A hydrogen bond exists between

A

H(electropositive) atom in one molecule and a lone pair on a highly electronegative atom ( O, N, F) on another molecule

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22
Q

Hydrocarbon

A

A compound that contains only hydrogen and carbon

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23
Q

Homologous series

A

A family of compounds containing the same functional group but with each successive member of the series differing by a CH2 group

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24
Q

Functional group

A

An atom/group responsible for the characteristic reactions of the compound

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25
Q

Aromatic

A

Compound containing a benzene ring C6H6

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26
Q

Aliphatic

A

Compound of carbon and hydrogen joined together in straight chains branches chains or non aromatic rings

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27
Q

Alicyclic

A

Aliphatic compounds arranged in non aromatic rings with or without side chains

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28
Q

Stuctural isomerism

A

Molecules with the same molecular formula but different structural formula

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29
Q

Homolytic fission

A

The breaking of a covalent bond where one electron from the bonding pair goes to each atom to form 2 radicals

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30
Q

Heterolytic fission

A

The breaking of a covalent bond where both electrons from the binding pair goes to the same atom to form 2 ions with opposite charges

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31
Q

General formula

A

The simplest algebraic formula for any member of a homologous series

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32
Q

Displayed formula

A

The relative positioning of the atoms and the bonds between them
This shows all the b one and how all the sims are joined together in the structure

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33
Q

Structural formula

A

Shows the minimum detail required for the arrangement of style in a molecule

Carboxyl group COOH Ester group COO

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34
Q

Skeletal formula

A

Hides every C atom and any H atoms which is directly attached to a C atom
Just leaves the carbon skeleton and any functional groups

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35
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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36
Q

Redox

A

A reaction where both oxidation and reduction takes place

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37
Q

Oxidation

A

The loss of electrons/ an increase in oxidation number

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38
Q

Reduction

A

The gain of electrons/ a decrease in oxidation number

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39
Q

Metallic bonding

A

The strong electrostatic attraction of a lattice of cations to a ‘sea’ of delocalised electrons

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40
Q

Haloalkane

A

Compounds in which a halogen atom has replaced at least one of the hydrogen atoms in an alkane chain

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41
Q

Nucleophile

A

An electron pair donor

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42
Q

Hydrolysis

A

An electron pair donor replace a halogen atom

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43
Q

A curly arrow shows

A

The movement of an electron pair to break or make a covalent bond

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44
Q

Dehydration

A

A reaction where a h2o molecule is removed from a saturated molecule to form an unsaturated molecule

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45
Q

Hydrated

A

When water of crystallisation is present in a crystal compound

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46
Q

Anhydrous

A

When all the waters of crystallisation have been removed from a compound

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47
Q

Water of crystallisation

A

The water present in a compound giving the compound a crystalline appearance

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48
Q

Enthalpy change

A

The amount of heat released or absorbed by a chemical reaction , carried out at constant pressure

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49
Q

Exothermic reaction

A

Where heat energy is released to surrounding

Delta H negative

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50
Q

Endothermic reaction

A

Where heat energy is absorbed from the surroundings

Delta H is positive

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51
Q

Average bond enthalpy

A

The average enthalpy change for the breaking of one mole of bonds in gaseous molecules

52
Q

Standard condition

A

25 degrees
1 atmosphere
1 mol

53
Q

Yield

A

The mass of a product obtained from a reaction

54
Q

% yield

A

Actual mass of product/ theoretical mass of product

X100

55
Q

Atom economy

A

Molecular mass of desired product/
Molecular mass of all products

X100

56
Q

A covalent bond vibrates more when

A

It absorbs infrared radiation

57
Q

Structural isomer

A

Molecules with the same molecular formula but different structural formula

58
Q

Dehydration

A

A reaction where are H2O molecule is removed from Saturated molecules to form an unsaturated molecule

59
Q

Ethanol+ sodium bromide+ sulfuric acid

A

CH3CH2Br
NaHSO4
H20

60
Q

4 characteristics of a dynamic equilibrium

A
  1. The rate of the forward reaction is equal to the rate of the reverse reaction
  2. The system is closed
  3. The concentration of reactants and products do not change
  4. The macroscopic properties do not change e.g. temperature pressure concentration
61
Q

Le Chateliers Principle

A

When a system In dynamic equilibrium is subjected to change the equilibrium position will shift to minimise the effect of the change

62
Q

The rate of a chemical reaction is

A

The change in concentration of a reactant or product per unit time

63
Q

Activation energy

A

The minimum energy required for the reaction to take place by the breaking of bonds in the reactants

64
Q

Rate at time ‘t’

A

Gradient of the tangent to the curve at time ‘t’

65
Q

Oxidising agent

A

A reagent that oxidise (takes electrons from) another species

66
Q

Reducing agent

A

A reagent that reduced (adds electrons to) another species

67
Q

Alkenes

3

A

Unsaturated compounds contain at least one multiple bonds between carbon atoms

In alkenes this bond is a C to C double bond

General formula for alkenes CnH2n

68
Q

C=C double bond

A

Made up of a sigma bond and pk bond
Restricted rotation of the pi bond
The sigma bond is formed Directly between carbon atoms by the direct single overlap of orbitals directly between bonding atoms
The pi bond Is formed by the double sideways overlap of adjacent P orbitals above and below the bonding C atoms

69
Q

Stereoisomerism

A

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

70
Q

E/Z isomerism criteria

Cis/ trans

A

Carbon carbon double bond because this cannot rotate

Each carbon of the carbon carbon double bond must have two different groups attached to it

Two groups on the carbon carbon double bond must be identical

71
Q

Chemical test for alkene functional group

A

Add bromine and shake

If the bromine is decolourised the compound is an Alkene

If the bromine is not decolourised the compound is not an Alkene

72
Q

Electrophile

A

An electron pair acceptor

73
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

74
Q

Standard enthalpy change of neutralisation

A

The enthalpy change that accompanies the formation of one mole of H2O from neutralisation under standard conditions

75
Q

Standard enthalpy change of formation

A

The enthalpy change when one mole of a compound is formed from its elements in their standard states under standard conditions

76
Q

Standard enthalpy change of combustion

A

The Enthalpy change For complete combustion of one mole of a substance under standard conditions all reactants and products being in their standard states

77
Q

Hesss law states that

A

The enthalpy change of a reaction depends only On the initial and final state and is independent of The route taken

78
Q

NMR spectroscopy

A

Involves the interaction of materials with the low-energy radio wave region of the electromagnetic spectrum

79
Q

Stereoisomers

A

Have the same structural formula but different spatial arrangement of their atoms

80
Q

Avogadros constant

A

The number of particle per mole of a substance

6.02 x 1023 mol-1)

81
Q

Molar gas volume

A

The gas volume per mole of a substance. This is 24.0 dm3mol-1 at room
temperature and pressure (RTP).

82
Q

Electron pair repulsion theory

A

The shape of simple covalent molecules and ions are determined by the number & type of electron
pairs around the central atom.
• Electron pairs repel one another as far apart as possible
• Lone pairs of electrons repel more strongly than bond pairs of electrons

83
Q

Standard solution

A

A solution of known concentration

84
Q

Standard states

A

Physical states under standard conditions.

85
Q

Lattice enthalpy

A

The enthalpy change when one mole of an ionic compound is formed from its gaseous ions (used as a measure of the strength of ionic bonding).

86
Q

Standard enthalpy change of solution

A

The enthalpy change when one mole of a compound (solute) is completely dissolved in water, under standard conditions

87
Q

STANDARD ENTHALPY CHANGE OF HYDRATION, ΔhydHθ:

A

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

88
Q

ENTROPY, S:

A

A measure of the dispersal of energy in a system which is greater, the more disordered a system

89
Q

(GIBBS) FREE ENERGY CHANGE, ΔG:

A

the balance between the enthalpy change (ΔH), the entropy change (ΔS) and temperature (T) for a process.
ΔG = ΔH - TΔS
ΔG, determines the feasibility of a reaction: a reaction is feasible if ΔG < 0.

90
Q

RATE OF REACTION:

A

The change in concentration of a reactant or a product per unit time.

91
Q

RATE EQUATION

A

: gives the relationship between the rate of reaction and the concentration of the
reactants raised to the powers of their orders.
Example, for the reaction: A + B products Rate equation: rate = k [A]m [B]n

92
Q

RATE CONSTANT:

A

‘k’ in the rate equation: the larger the value of k, the faster the reaction. k is constant at a constant temperature and increases with temperature (Arrhenius).

93
Q

ORDER

A

: how the concentration of a reactant affects the rate of the reaction. In the rate equation above, Order with respect to A = m
Order with respect to B = n
Overall order = m + n

94
Q

Catalyst

A

CATALYST: Increases the rate of a reaction without being used up by the overall reaction. It allows the reaction to proceed via a different route with lower activation energy.

95
Q

HOMOGENEOUS CATALYST:

A

Catalyst is in the same physical state as the reactants (frequently, the aqueous or gaseous state).

96
Q

HETEROGENEOUS CATALYST:

A

Catalyst has a different physical state from the reactants (frequently, reactants are gases while the catalyst is a solid).

97
Q

RATE-DETERMINING STEP:

A

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

98
Q

HALF-LIFE:

A

The time taken for the concentration of a reactant to fall to half of its original concentration.
(For a first order reaction, half-life is constant)

99
Q

DYNAMIC EQUILIBRIUM:

A

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 reactants and products do not change.

100
Q

EQUILIBRIUM CONSTANT:

A 
For an equilibrium reaction: A + B C + D
                   Kc = [C]c [D]d [A]a [B]b
[ ] = equilibrium concentrations
Kp =
p(C)c x p(D)d p(A)a x p(B)b
p = partial pressures (for gases)
101
Q

MOLE FRACTION, x(A) =

A

number of moles of A . total number of moles in gas mixture

102
Q

PARTIAL PRESSURE, p(A) =

A

mole fraction of A x total pressure P

103
Q

CONJUGATE ACID-BASE PAIR:

A

A pair of two species that transform into each other by the gain or loss of a proton (H+).

104
Q

PH

A

pH = -log[H+] and [H+] = 10-pH

105
Q

ACID DISSOCIATION CONSTANT, Ka:

A

For a weak acid: HA Ka = [H+] [A-] units = moldm-3
[HA]
and pKa = - log Ka

106
Q

IONIC PRODUCT OF WATER, Kw:

A

The dissociation of water: H2O Kw = [H+] [OH-] units = mol2dm-6
At 250C Kw = 1.00 x 10-14 mol2dm-6

107
Q

BUFFER SOLUTION:

L

A

A system that minimises pH changes on addition of small amounts of an acid or base.

108
Q

DISPLACEMENT REACTION:

A

A reaction in which a more reactive element (halogen) displaces a less reactive element (halogen) from an aqueous solution of its halide ions.

109
Q

DISPROPORTIONATION:

A

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

110
Q

SUBSTITUTION REACTION:

A

A reaction where an atom or group in a molecule is replaced by another atom or group.

111
Q

ADDITION REACTION:

A

A reaction where a group is added across a double bond of an unsaturated molecule to make a saturated molecule (one product).

112
Q

ELIMINATION REACTION:

A

A reaction where an atom or group is removed from a molecule to make an unsaturated molecule.

113
Q

OXIDATION REACTION:

A

A reaction where oxygen is added and/ or hydrogen is removed from a molecule.

114
Q

CONDENSATION REACTION:

A

A reaction where an H2O molecule is lost when two molecules join together.

115
Q

DEHYDRATION REACTION:

A

A reaction where a H2O molecule is removed from a saturated molecule to form an unsaturated molecule.

116
Q

HYDROLYSIS REACTION:

A

A chemical reaction involving water or an aqueous solution, which causes the breaking of a bond, splitting a reactant molecule into two products.

117
Q

SIGMA () BOND:

A

Single end-on (axial) overlap of orbitals directly between bonding atoms, allowing free rotation of the bond.

118
Q

PI BOND

A

Double sideways overlap of adjacent p orbitals above and below the plane of the bonding atoms, with restricted rotation of the bond.

119
Q

ALKYL GROUP:

A

Of formula CnH2n+1

120
Q

SATURATED:

A

Containing single carbon-carbon bonds only.

121
Q

UNSATURATED:

A

Containing at least one multiple carbon-carbon bond, including C=C, C=C and aromatic rings.

122
Q

VOLATILITY:.

A

The ease with which a liquid turns into a gas

123
Q

PRECIPITATE:

A

An insoluble solid formed when two solutions are mixed together.

124
Q

SOLUTION:

A

A homogeneous mixture composed of two or more substances. A solution consists of a solute and a solvent. The solute is the substance that is dissolved in the solvent. These are usually transparent.

125
Q

DISTILLATION:

A

The technique of heating a liquid to create vapour which is collected when cooled and condensed, separate from the original liquid. (often used to separate liquids based on their boiling points)

126
Q

HEAT UNDER REFLUX:

A

The continuous boiling and condensing of a liquid (in a condenser) preventing loss of volatile liquids from a heated reaction vessel

Chemistry A LEVEL (10 decks)

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