finals Flashcards
(168 cards)
1
Q
how do you use the nuclear symbol:
A
X
Z
A
A = mass number
Z = number of protons
2
Q
what is an isotope
A
atoms of the same element with different neutron numbers
3
Q
what is the function of mass spectrometry
A
determines the structure of an organic compound from the fragmentation process
4
Q
what are the steps of mass spectrometry
A
vaporisation
ionisation
fragmentation
5
Q
how to determine mass spectrum of a compound?
A
Each line shows a loss of a fragment
(see section 22 in data booklet)
molecular ion peak closest to the right determines the Mr
6
Q
how is an emissions spectrum produced
A
when provided with energy, the electron can jump from n=1 to a higher energy level (excitation)
7
Q
continuous vs line spectrum
A
continuous = non discrete lines
line spectrum = discrete lines
8
Q
features of a hydrogen emissions spectrum
A
- energy levels are discrete
- lines converge towards high frequency
9
Q
what are the different series in an emissions spectrum
A
Paschen (Infrared) = N=6-4 to N=3
Balmer (Visible light) = N=5-3 to N=2
Lyman (UV) = N=4-2 to N=1
10
Q
what is the main energy level and how many electrons can it hold
A
like the outermost shell
2n^2
11
Q
what are the 4 sublevels
A
s, p, d, f
12
Q
what is the Aufbau principle
A
electrons first fill subshells of the lowest available energy, then fill subshells of higher energy. For example, the 1s subshell is filled before the 2s subshell is occupied.
13
Q
what is the Hund’s rule
A
every orbital in a subshell is singly occupied with one electron before any one orbital is doubly occupied, and all electrons in singly occupied orbitals have the same spin.
14
Q
what is the Pauli exclusion principle
A
A maximum of two electrons can occupy the same orbital. The two electrons sharing the same orbital must have opposite spins, or they must be antiparallel.
15
Q
what is the limit of convergence
A
Energy levels (shells) become closer together as we move away from the nucleus
16
Q
how to calculate ionisation energy?
A
c = fλ
E = hf
c = 3.00*10^8
f = frequency
λ = convergence limit = 91.2 nm
E = energy required to remove 1 e- (J)
h = 6.63 x 10^34
17
Q
successive ionisation energy
A
more and more electrons are removed, each from an ion that is becoming increasingly positive
always increases
18
Q
trends in first IE
A
across a period:
- nuclear charge increases
- atomic radius decreases
down a group:
- number of energy levels increase, so more shielding, so decreases
discontinuities in group 3
- from Mg to Al (because it jumps from 3s^2 to 3s^2,3p^2)
- from P to S (because it goes from 3p^3 to 3p^4)
19
Q
how to calculate number of molecules in n moles of a substance
A
n * avogadro’s constant
20
Q
what is the unit of molar mass
A
g mol^-1
21
Q
how to convert between empirical and molecular formula
A
- convert percentage composition to mass
- convert mass to moles using the Mr of the element
- divide all the moles by the smallest mole
- each result is the number of that element’s atoms
22
Q
what is avogadro’s law
A
volume is directly proportional to moles at constant temperature and pressure
23
Q
combined and ideal gas laws
A
combined: (P1V1)/T1 = (P2V2)/T2
ideal gas: pV = nRT
24
Q
cations vs anions (in bonding and structure)
A
cations = (+) metal ions lose electrons
anions = (-) non metal ions gain electrons
25
what is an ionic bond
electrostatic attraction between oppositely charged ions
(metal + non-metal)
26
physical properties of ionic compounds
high melting points
hard and brittle
dissociate into ions when dissolved in water
electrical conductor when in molton/aqueous
27
what is lattice enthalpy
a measure of the strength of the forces between the ions in an ionic solid to a gaseous state
28
what are the components of lattice enthalpy
FAI(EA)L
exo 1. Standard enthalpy of formation
endo 2. Standard enthalpy of atomisation
endo 3. Ionisation energy
exo for 1st, endo for 2nd 4. Electron Affinity
exo 5. Lattice enthalpy
29
what is a covalent bond
the electrostatic attraction between a shared pair of electrons and the positively charged nuclei.
30
coordination bond
a covalent bond, but both electrons are from one atom
= same bond length and strength as covalent
31
VSEPR models
answer in goodnotes
32
bond vs molecular polarity
bond polarity = depends on electronegativity difference
- the more electronegative, the more polar
molecular polarity = depends on bond polarity and molecular geometry
if symmetrical = non-polar
33
diamond
each c atom covalently bonded to 4 others
- non conductor
- very efficient thermal conductor
- brittle
- high melting point
- used in jewellery, tools and machinery
34
graphite
each c atom covalently bonded to 3 others, forms sheets
- conductor
- not a good thermal conductor
- brittle
- very high melting point (most stable allotrope of carbon)
- used in pencils + electrolysis
35
graphene
each c atom covalently bonded to 3 others, forms ONE sheet
- VERY good conductor
- BEST thermal conductor
- very flexible and very strong
- very high melting point
- used in touch screens and high performance electronic devices
36
C60 fullerene
sphere made of 60 carbons
- poor conductor
- very low thermal conductivity
- in the form of powder, very light and strong
- low melting point (most stable allotrope of carbon)
- used in carbon nanotubes, catalysts
37
what are the different intermolecular forces and what are variance in strengths
London dispersion < Dipole-dipole < Hydrogen bonding
38
when does a molecule have dipole-dipole
when it is polar
39
when does a molecule have LDF
always
40
when does a molecule have hydrogen bonding
when the molecule has a H atom bonded covalently to N/O/F
weaker than a covalent bond
41
physical properties of covalent bonds
low B.P. and M.P.
non conductor of electricity
solubility = substances with the same type of polarity dissolve each other (like dissolves like)
42
how to calculate Rf
the distance traveled by the compound divided by the distance traveled by the solvent front
43
when is there a resonance structure
when there is more than 1 possible position for a double bond in a molecule
44
formal charge formula
no. of valence - 1/2 no. of bonding - non bonding
45
how are sigma bonds formed
head on combination of atomic orbitals where the electron density is concentrated along the bond axis
46
how are pi bonds formed
lateral combination of p-orbitals where the electron density is concentrated on opposite sides of the bond axis
47
how to deduce the number of sigma and pi bonds in a molecule?
all single bonds are sigma bonds
double = 1 pi 1 sigma
triple = 2 pi and 1 sigma
48
what is hybridisation
mixing of atomic orbitals to form new hybrid orbitals for bonding
49
when does sp3 hybridisation occur
when an atom has 4 electron domains, and a tetrahedral electron domain geometry
e.g. CH4
- the 2s and 3 2p orbitals undergo sp3 hybridisation
forming 4sp2 orbitals
50
when does sp2 hybridisation occur
when an atom has 3 electron domains, and a trigonal planar electron domain geometry
e.g. C2H4
- 2s and 2 2p orbitals undergo sp2 hybridisation
forming 3 sp2 orbitals, leaving 1p orbital
51
when does sp hybridisation occur
when an atom has 2 electron domains, and a linear electron domain geometry
e.g. C2H2
- 2s and 2p orbitals undergo sp hybridisation
- forming 2 sp orbitals, leaving 2p orbtial
52
what is a metallic bond
electrostatic attraction between a lattice of cations and delocalized electrons.
53
physical properties of metals
good thermal and electric conductor
malleable
high M.P., B.P.
54
what does the strength of a metallic bond depend on?
charge of ions = the higher the charge of the ion, the stronger the attraction, and thus, the stronger the bond
radius of metallic ion = The smaller the radius of the cations, the shorter the distance between the positive nucleus at its centre and the delocalized electrons around it. As a result, electrostatic forces of attraction between them are stronger.
55
why do transition metals have high M.P. and good electrical conductivity?
they have delocalised d-electrons
56
physical properties of alloys
harder, because the lattice of positive cations cannot slide across one another
corrosion resistant
examples: bronze, brass, stainless steel
57
what are polymers
large molecules made from repeating subunits called monomers
PLASTICS:
They are light in weight and are chemically stable.
Easily moulded into different shapes and sizes.
Good insulation and low thermal conductivity.
58
what are addition polymers
when the double bond in a monomer is broken
59
what are condensation polymers
when two functional groups react and release a small molecule (like H2O)
---> condensation is the opposite of hydrolysis
60
where are the s p d f blocks on the periodic table
look at goodnotes
61
what is periodicity
trends in properties across a period and down a group
62
periodicity of atomic radius
ACROSS: decrease
- increase no. of protons
- similar shielding
- decrease distance from nucleus and electrons
DOWN: increase
- increase number of shells
- increase shielding
63
periodicity of ionic radius
ACROSS: Group 3
As charge gets more negative, radius increases
DOWN: increase
- increase in shielding
64
periodicity of ionisation energy
ACROSS: increase
- increase proton number
- similar shielding
- decrease atomic radius
- increase electrostatic attraction
DOWN: decrease
- atomic radius
65
periodicity of electron affinity
ACROSS: increase
- more protons
- similar shielding
DOWN: decrease
- more shielding
- less exothermic
66
periodicity of electronegativity
ACROSS: increase
- more protons
- similar shielding
DOWN: decrease
- more shielding
- less exothermic
67
periodicity of melting and boiling points
ACROSS:
- giant covalent has the highest (like Si)
- simple molecular (covalent), compare IMF
DOWN:
- group 1 (ionic radius inc., charge stays the same) = decrease
- group 17 (intermolecular forces, LDF strongest in iodine, increase down)
68
trends in properties of elements down a group
GROUP 1 ALKALI METALS + water
--> metal hydroxide + water
- increase down (more shells, more shielding, inc. atomic radius)
GROUP 17 HALOGENS AND HALIDES --> displacement
69
rules for oxidation states
F = -1
H = +1 unless hydrides (1 H)
O = -2 unless OF2 (+2), and Peroxides (H2O2 --> -1)
70
why are transition metals coloured
partially filled d-orbitals
- split d-orbitals by ligands
- energy gap is correspondent to the visible light region
- e- promoted from lower to upper d-orbital
- absorb certain wavelength
- complimentary colour is transmitted
71
functional groups
look at ipad
72
what is a homologous series
successive members differ by a common structural unit
73
what are structural isomers
same molecular formula but different structural formula
74
what are chain isomers
different in main chain and branching
75
what are position isomers
same functional group, diff in positions
76
what are functional group isomers
diff functional group
77
what are stereoisomers
same structural formula, diff spacial arrangement of atoms
78
what are cis-trans isomers
cis = like
H\ /H
C=C
Cl/ \Cl
trans = like
H\ /Cl
C=C
Cl/ \H
79
what are chiral carbons
carbons bonded to 4 diff R-groups
80
classification of carbon atoms in alcohols, halogenoalkanes and nitrogen atoms in amines
alcohols: C-OH
halogenoalkanes = C-X (halogen)
amine = N-H
primary = bonded to 1 R group
secondary = bonded to 2 R groups
tertiary = bonded to 3 R groups
81
how do you determine the structure of a molecule from its proton environments (^1HNMR)
1. number of signals = number of environments
2. integration trace = ratio of H atoms in each environment
3. chemical shift = formula booklet
4. splitting patterns = number of H atoms on the adjacent carbon atoms (n+1, so 0 H atoms = singlet, 1 H = doublet etc)
82
endothermic vs exothermic
endothermic = temp of surroundings decreases
energy profile = low to high
exothermic = temp of surroundings increases
energy profile = high to low
83
how to calculate enthalpy change?
Q = mc deltaT
deltaH = -Q/n
84
bond breaking vs bond making
bond breaking = absorbs energy
bond making = releases energy
85
what is Hess's law
the enthalpy change for a reaction is independent of the pathway between the initial and final states.
86
what is standard enthalpy of formation:
deltaHf
mostly exothermic
when 1 mol of compound is formed from its elements in their standard states with their standard conditions
in kJmol-1
87
what is standard enthalpy of combustion:
deltaHc
exothermic
when 1 mole of substance is burned in excess oxygen under standard conditions
88
how to calculate enthalpy change using standard enthalpy of formation
Products - Reactants
89
how to calculate enthalpy change using standard enthalpy of combustion
Reactants - Products
90
what types of compounds undergo combustion? how to form an equation?
reactive metals, non-metals and organic compounds
X + O2 --> __ + ___
91
what are the products of incomplete combustion
CO
92
advantages and disadvantages of different fossil fuels
coal
- cheap, abundant, long lifespan, safe
- produces large amounts of pollution, difficult to transport, potentially radioactive
oil
- easy to store and transport, impurities easy to remove, high energy density
- produces large amounts of pollution, oil spills, safety issues around drilling
natural gas
- cheapest, easy to store and transport, relatively clean
- produces large amounts of pollution, expensive, safety issues around pressurised containers
93
what are biofuels and what are their adv/disadvs
= produced from biological fixation of carbon over a short period of time during photosynthesis
bioethanol, biodiesel, biogas
adv: renewable, reduce pollution, can provide jobs in the agriculture sectors
disadv: high cost, takes space, lower specific energy
94
what is entropy
measure of dispersal or distribution of matter
higher entropy = more disorder
solid/liquid --> gas = positive entropy
more moles of gas --> less = negative entropy
95
how to calculate entropy of a system?
sum of entropy (products) - sum of entropy (reactants)
96
how to calculate entropy of surroundings?
-enthalpy change/temperature
97
calculating Gibbs energy
if spontaneous = deltaG is negative
98
deciphering spontaneity with deltaH and deltaG
spontaneous = S
non spontaneous = NS
high temp = HT
any temp = AT
low temp = LT
delta H delta G
+ + S @ HT
+ - NS @ AT
- + S @ AT
- - S @ LT
99
how does deltaG change as the reaction approaches equilibrium?
as it approaches equilibrium, deltaG becomes less negative, finally reaching 0
100
how to calculate percentage yield?
actual/theoretical yield *100%
101
how to calculate atom economy?
Molecular mass of desired / sum of molecular mass of all reactants * 100
102
how do reactions occur
result of collisions of sufficient energy and orientation
103
factors that influence the rate of reaction
increase pressure = increase
increase conc. = increase
increase SA = increase
increase temp = increase
catalyst = increase
104
what is the rate equation
aA + bB --> cC + dD
Rate = k [A]^m [B]^n
k = rate constant
m, n = order
105
rate order diagrams
look at ipad
106
how to calculate equilibrium constant?
-------[C]^c[D]^d
Kc = ––––––––––
[A]^a[B]^b
107
effect of change in concentration on equilibrium
increase conc on the left, shift to the right
increase conc on the right, shift to the left
108
effect of change in pressure on equilibrium
increase pressure favours side with less moles of gas, so will shift that way
109
effect of change in temperature on equilibrium
increase temperature, shifts endo
decrease temperature, shifts exo
110
how to calculate reaction quotient
at any time, can be at eqm or not
[C]^c[D]^d
Kc = ––––––––––
[A]^a[B]^b
111
relationship between deltaG and K
K>1 = deltaG < 0
K=1 = deltaG = 0
K<1 = deltaG >0
112
what are Brønsted-Lowry acids?
proton donors
113
what are Brønsted-Lowry bases?
proton acceptors
114
conjugate acid-base pair
differ by 1 proton
acid = has the proton
base = missing a proton (charge +)
115
amphiprotic definition
can act as both an Brønsted-Lowry acid or base
116
how to calculate pH?
look at data booklet
117
strengths of acids and bases
strong acids = good proton donors, produce weak conjugate bases
weak acids = poor proton donors, produce strong conjugate bases
strong bases = good proton acceptors, produce weak conjugate acids
weak bases = weak proton acceptors, produce strong conjugate acids
118
reactions of acids:
acid + metal
acid + metal (hydr)oxide
acid + metal (hydrogen) carbonate
acid + ammonia
acid + metal = salt + hydrogen
acid + metal (hydr)oxide = salt + H2O
acid + metal (hydrogen) carbonate = salt + H2O + CO2
acid + ammonia = ammonium salts
119
strengths of weak acids and bases according to Ka, Kb, pKa or pKb
strong acid: large Ka and small pKa
strong base: large Kb and small pKb
120
how to calculate Kw and pKw?
Kw = ion product of water (1.0 x 10^-14)
Ka * Kb
pKa * pKb = pKw
pKw = 14
121
how to make a salt using acids and bases?
salt hydrolysis
122
salt hydrolysis between a strong acid and a weak base
acidic salt
123
salt hydrolysis between a strong acid and a strong base
neutral salt
124
salt hydrolysis between a weak acid and a strong base
basic salt
125
salt hydrolysis between a weak acid and a weak base
depends, but almost always neutral
126
salt hydrolysis with a metal ion with a high charge density
acidic salt
127
pH curve of strong acid into strong base titration
extreme high to extreme low
128
pH curve of strong base into strong acid titration
extreme low to extreme high
129
pH curve of a strong base into a weak acid titration
mid low to mid high
130
pH curve of a strong acid into a weak base titration
mid high to mid low
131
what are acid-base indicators?
weak acids
132
what is a buffer solution
resists change in pH on the addition of small
133
what does the pH of a buffer solution depends on?
the pKa or pKb of its acid or base
the ratio of the concentration
134
what is an acidic buffer made of
weak acid + salt of the conjugate base
135
what is a basic buffer made of
weak base + salt of the conjugate acid
136
what are the two methods of making an acidic buffer
directly mix
excess weak acid + strong base
137
what are the two methods of making a basic buffer
directly mix
excess weak base + strong acid
138
which side are the electrons on for oxidation half equation
right side
139
which side are the electrons on for reduction half equation
left side
140
relative ease of oxidation of metals
down the group (1&2), oxidation increases
141
relative ease of reduction of halogens
down the group (7), reduction decreases
142
what is the function of a primary (voltaic cell)?
converts energy from redox to electrical
143
what are the electrodes in an electrochemical cell?
anode = positive, oxidation
cathode = negative, reduction
144
what are secondary cells
rechargeable
can reverse their redox reactions using electrical energy
145
what is an electrolytic cell
converts electrical energy to chemical energy
146
what are the electrodes in a voltaic cell
anode: negative, oxidation
cathode: positive, reduction
147
what is the function of a salt bridge
complete the circuit formed using mobile ions
ions flow to balance the charge of the electrolytes
148
explain oxidation of primary alcohols
using distillation:
primary alcohol --> aldehyde
using reflux:
primary alcohol --> carboxylic acid
149
explain oxidation of secondary alcohols
secondary alcohol --> ketone
using reflux
150
reduction of oxidised products of alcohols
using LiAlH4
carboxylic acid --> aldehyde --> primary alcohol
151
what is the relationship between standard electrode potential and spontaneity
when E⦵ > 0, it is spontaneous
152
pros and cons of using rechargeable batteries
advantages:
lead-acid = can deliver lots of energy very quickly
NiCad cells = cannot leak because it is not a liquid or paste
lithium-ion - non toxic, high voltage
disadvantages:
lead-acid = heavy and toxic
NiCad cells = expensive
lithium ion = expensive
153
pros and cons of using a general primary cell
pro: cheap, light, long shelf life
con: single use (bad for environment)
154
pros and cons of using fuel cells
pros: reduced pollution, more efficient
cons: expensive, safety issues w/ hydrogen
155
explain the reduction of unsaturated compounds
addition of hydrogen, lowers the degree of unsaturation
alkynes --> alkenes --> alkanes
156
what is a radical
molecular entity that has an unpaired electron
157
how are radicals produced
homolytic fission, in the presence of UV light, during radical substitution
158
what is radical substitution and draw the mechanism
radical substitution --> occurs to alkanes
steps: initiation, propagation, termination
159
what is a nucleophile
reactant that forms a bond to its reaction partner by donating BOTH bonding electrons
160
what is nucleophilic substitution and what is the mechanism of SN1 and SN2
for halogenoalkanes
Bimolecular nucleophilic substitution (SN2) - primary and secondary
Unimolecular nucleophilic substitution (SN1) - secondary and tertiary
161
what is an electrophile?
a reactant that forms a bond to a nucleophile by accepting both bonding electrons from it
162
what is electrophilic addition
alkenes
majors vs minors:
major = more R groups
163
what is a lewis acid
electron pair acceptor
164
what is a lewis base
electron pair donor
165
what is a ligand
a species that has a lone pair of electrons that can be donated to form a coordination bond
166
which nucleophilic substitution reaction is the fastest? rank in order from fastest to slowest
RBr, RCl, RI
RI > RBr > RCl
167
what is electrophilic substitution?
for benzene
168
what are the reagents for the nitration of benzene?
conc. HNO3 and conc. H2SO4
