Key Words Flashcards
1
Q
Mole
A
The amount of substance containing as many particles As there are carbon atoms in exactly 12 g of carbon 12
2
Q
Molar mass
A
The mass in grams per mole of a substance
3
Q
An acid is
A
A proton donor that dissociates its ions
4
Q
A strong acid
A
Completely dissociates it’s ions I’m aqueous solution
5
Q
A weak acid
A
Partially dissociates into its ions in aqueous solution
6
Q
A base
A
A proton acceptor
7
Q
An alkali is
A
A base that dissolves In water and releases 0H ions in aqueous solution
8
Q
A salt is produced when
A
The H Ion of an acid is replaced by a metal iOn or NH4
9
Q
Ionic bonding
A
The electrostatic attraction between opposite Lee charged ions
10
Q
Covalent bonding
A
The strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms
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
12
Q
Average bond enthalpy
A
Can be used as a measurement of covalent bond strength
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
14
Q
Electronegativity
A
The ability of an atom to attract the bonding electrons towards itself in a covalent bond
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
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
17
Q
Reacting volume of gases
A
1 mole of any gas occupies a volume of 24dm^3
At RTP
18
Q
Ideal gas equation
A
pV=nRT
19
Q
Empirical formula
A
The simplest whole number ratio of atoms of each element present in a compound
20
Q
Molecular formula
A
The actual number and type of atoms of each element in a molecule
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
22
Q
Hydrocarbon
A
A compound that contains only hydrogen and carbon
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
24
Q
Functional group
A
An atom/group responsible for the characteristic reactions of the compound
25
Aromatic
Compound containing a benzene ring C6H6
26
Aliphatic
Compound of carbon and hydrogen joined together in straight chains branches chains or non aromatic rings
27
Alicyclic
Aliphatic compounds arranged in non aromatic rings with or without side chains
28
Stuctural isomerism
Molecules with the same molecular formula but different structural formula
29
Homolytic fission
The breaking of a covalent bond where one electron from the bonding pair goes to each atom to form 2 radicals
30
Heterolytic fission
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
31
General formula
The simplest algebraic formula for any member of a homologous series
32
Displayed formula
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
33
Structural formula
Shows the minimum detail required for the arrangement of style in a molecule
Carboxyl group COOH Ester group COO
34
Skeletal formula
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
35
Oxidation number
A measure of the number of electrons that an atom uses to bond with atoms of another element
36
Redox
A reaction where both oxidation and reduction takes place
37
Oxidation
The loss of electrons/ an increase in oxidation number
38
Reduction
The gain of electrons/ a decrease in oxidation number
39
Metallic bonding
The strong electrostatic attraction of a lattice of cations to a ‘sea’ of delocalised electrons
40
Haloalkane
Compounds in which a halogen atom has replaced at least one of the hydrogen atoms in an alkane chain
41
Nucleophile
An electron pair donor
42
Hydrolysis
An electron pair donor replace a halogen atom
43
A curly arrow shows
The movement of an electron pair to break or make a covalent bond
44
Dehydration
A reaction where a h2o molecule is removed from a saturated molecule to form an unsaturated molecule
45
Hydrated
When water of crystallisation is present in a crystal compound
46
Anhydrous
When all the waters of crystallisation have been removed from a compound
47
Water of crystallisation
The water present in a compound giving the compound a crystalline appearance
48
Enthalpy change
The amount of heat released or absorbed by a chemical reaction , carried out at constant pressure
49
Exothermic reaction
Where heat energy is released to surrounding
Delta H negative
50
Endothermic reaction
Where heat energy is absorbed from the surroundings
Delta H is positive
51
Average bond enthalpy
The average enthalpy change for the breaking of one mole of bonds in gaseous molecules
52
Standard condition
25 degrees
1 atmosphere
1 mol
53
Yield
The mass of a product obtained from a reaction
54
% yield
Actual mass of product/ theoretical mass of product
X100
55
Atom economy
Molecular mass of desired product/
Molecular mass of all products
X100
56
A covalent bond vibrates more when
It absorbs infrared radiation
57
Structural isomer
Molecules with the same molecular formula but different structural formula
58
Dehydration
A reaction where are H2O molecule is removed from Saturated molecules to form an unsaturated molecule
59
Ethanol+ sodium bromide+ sulfuric acid
CH3CH2Br
NaHSO4
H20
60
4 characteristics of a dynamic equilibrium
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
Le Chateliers Principle
When a system In dynamic equilibrium is subjected to change the equilibrium position will shift to minimise the effect of the change
62
The rate of a chemical reaction is
The change in concentration of a reactant or product per unit time
63
Activation energy
The minimum energy required for the reaction to take place by the breaking of bonds in the reactants
64
Rate at time ‘t’
Gradient of the tangent to the curve at time ‘t’
65
Oxidising agent
A reagent that oxidise (takes electrons from) another species
66
Reducing agent
A reagent that reduced (adds electrons to) another species
67
Alkenes
| 3
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
C=C double bond
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
Stereoisomerism
Compounds with the same structural formula but with a different arrangement of atoms in space
70
E/Z isomerism criteria
Cis/ trans
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
Chemical test for alkene functional group
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
Electrophile
An electron pair acceptor
73
Standard enthalpy change of reaction
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
Standard enthalpy change of neutralisation
The enthalpy change that accompanies the formation of one mole of H2O from neutralisation under standard conditions
75
Standard enthalpy change of formation
The enthalpy change when one mole of a compound is formed from its elements in their standard states under standard conditions
76
Standard enthalpy change of combustion
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
Hesss law states that
The enthalpy change of a reaction depends only On the initial and final state and is independent of The route taken
78
NMR spectroscopy
Involves the interaction of materials with the low-energy radio wave region of the electromagnetic spectrum
79
Stereoisomers
Have the same structural formula but different spatial arrangement of their atoms
80
Avogadros constant
The number of particle per mole of a substance
6.02 x 1023 mol-1)
81
Molar gas volume
The gas volume per mole of a substance. This is 24.0 dm3mol-1 at room
temperature and pressure (RTP).
82
Electron pair repulsion theory
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
Standard solution
A solution of known concentration
84
Standard states
Physical states under standard conditions.
85
Lattice enthalpy
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
Standard enthalpy change of solution
The enthalpy change when one mole of a compound (solute) is completely dissolved in water, under standard conditions
87
STANDARD ENTHALPY CHANGE OF HYDRATION, ΔhydHθ:
The enthalpy change when one mole of isolated gaseous ions is dissolved in water forming one mole of aqueous ions, under standard conditions
88
ENTROPY, S:
A measure of the dispersal of energy in a system which is greater, the more disordered a system
89
(GIBBS) FREE ENERGY CHANGE, ΔG:
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
RATE OF REACTION:
The change in concentration of a reactant or a product per unit time.
91
RATE EQUATION
: 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
RATE CONSTANT:
‘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
ORDER
: 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
Catalyst
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
HOMOGENEOUS CATALYST:
Catalyst is in the same physical state as the reactants (frequently, the aqueous or gaseous state).
96
HETEROGENEOUS CATALYST:
Catalyst has a different physical state from the reactants (frequently, reactants are gases while the catalyst is a solid).
97
RATE-DETERMINING STEP:
The slowest step of a reaction mechanism of a multi-step reaction
98
HALF-LIFE:
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
DYNAMIC EQUILIBRIUM:
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
EQUILIBRIUM CONSTANT:
```
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
MOLE FRACTION, x(A) =
number of moles of A . total number of moles in gas mixture
102
PARTIAL PRESSURE, p(A) =
mole fraction of A x total pressure P
103
CONJUGATE ACID-BASE PAIR:
A pair of two species that transform into each other by the gain or loss of a proton (H+).
104
PH
pH = -log[H+] and [H+] = 10-pH
105
ACID DISSOCIATION CONSTANT, Ka:
For a weak acid: HA Ka = [H+] [A-] units = moldm-3
[HA]
and pKa = - log Ka
106
IONIC PRODUCT OF WATER, Kw:
The dissociation of water: H2O Kw = [H+] [OH-] units = mol2dm-6
At 250C Kw = 1.00 x 10-14 mol2dm-6
107
BUFFER SOLUTION:
| L
A system that minimises pH changes on addition of small amounts of an acid or base.
108
DISPLACEMENT REACTION:
A reaction in which a more reactive element (halogen) displaces a less reactive element (halogen) from an aqueous solution of its halide ions.
109
DISPROPORTIONATION:
A reaction in which the same element is both oxidised and reduced.
110
SUBSTITUTION REACTION:
A reaction where an atom or group in a molecule is replaced by another atom or group.
111
ADDITION REACTION:
A reaction where a group is added across a double bond of an unsaturated molecule to make a saturated molecule (one product).
112
ELIMINATION REACTION:
A reaction where an atom or group is removed from a molecule to make an unsaturated molecule.
113
OXIDATION REACTION:
A reaction where oxygen is added and/ or hydrogen is removed from a molecule.
114
CONDENSATION REACTION:
A reaction where an H2O molecule is lost when two molecules join together.
115
DEHYDRATION REACTION:
A reaction where a H2O molecule is removed from a saturated molecule to form an unsaturated molecule.
116
HYDROLYSIS REACTION:
A chemical reaction involving water or an aqueous solution, which causes the breaking of a bond, splitting a reactant molecule into two products.
117
SIGMA () BOND:
Single end-on (axial) overlap of orbitals directly between bonding atoms, allowing free rotation of the bond.
118
PI BOND
Double sideways overlap of adjacent p orbitals above and below the plane of the bonding atoms, with restricted rotation of the bond.
119
ALKYL GROUP:
Of formula CnH2n+1
120
SATURATED:
Containing single carbon-carbon bonds only.
121
UNSATURATED:
Containing at least one multiple carbon-carbon bond, including C=C, C=C and aromatic rings.
122
VOLATILITY:.
The ease with which a liquid turns into a gas
123
PRECIPITATE:
An insoluble solid formed when two solutions are mixed together.
124
SOLUTION:
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
DISTILLATION:
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
HEAT UNDER REFLUX:
The continuous boiling and condensing of a liquid (in a condenser) preventing loss of volatile liquids from a heated reaction vessel
