Module 1+2+3 Flashcards

(136 cards)

1
Q

what does the term ‘lanthanides’ refer to

A

elements from Ce-Lu

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2
Q

what does the term ‘lanthanoids’ refer to

A

elements from La-Lu

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3
Q

what does the term ‘rare earths’ refer to

A

elements from La-Lu, Sc and Y

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4
Q

what does the term ‘actinides’ refer to

A

elements from Th-Lr

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5
Q

what does the term ‘actinoids’ refer to

A

elements from Ac-Lr

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6
Q

what are 2 early applications of the f-elements

A
gas mantle
pyrophoric alloy (lighter flint)
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7
Q

what compound was found in a gas mantle and what did it do

A

CeO2

coverted light from gas lamp to heat - significantly brighter

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8
Q

what are 3 fields of use for lanthanoids

A

magnetic
optical
materials

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9
Q

what applications do lanthanoids have in magnetics

A

rare earth magnets (Nd) - used in wind turbines

MRI contrast agents

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10
Q

what applications do lanthanoids have in the optical field

A

security inks
lasers
lighting

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11
Q

what applications do lanthanoids have in materials

A

can form specialist alloys

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12
Q

what are 2 key applications of actinoids

A
nuclear power (235U)
long life batteries (238Pu)
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13
Q

which are the 3 most abundant lanthanoids

A

La, Ce, Nd

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14
Q

which is the only lanthanoid not found in nature and why

A

Pm - radioactive

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15
Q

what 2 common elements are less abundant than lanthanoids

A

iodine

mercury

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16
Q

what are the 2 main mineral structures of lanthanoid sources

A

LnFCO3 - Bastnaesite

LnPO4 - Monazite

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17
Q

what are the top 4 locations with reserves and what percentage do they hold of rare earths

A

china 1/3
vietnam 1/6
brazil 1/6
russia 1/6

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18
Q

where are 97% of rare earths produced

A

china

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19
Q

elements above what atomic number and element are radioactive

A

83 (Bismuth)

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20
Q

how does the abundance of actinoids compare to lanthanoids

A

much lower

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21
Q

which are the 2 actinoids that exist in more than trace amounts

A

U 2.4 ppm

Th 12 ppm

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22
Q

what is the uranium decay series

A

235U - 231Th - 231Pa - 227Ac — 207Pb

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23
Q

what % of U is 235U

A

0.7%

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24
Q

what is the synthetic route of Ac from Ra

A

226Ra - 227Ra - 227Ac

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25
what is the synthetic route of Th - Pa
230Th - 231Th - 231 Pa
26
what is the synthetic route of U - Pu
238U - 239U - 239Np - 239Pu
27
what is the synthetic route of U - Fm
238U + 17n - 255U - 255Np - 255Pu --- 255Fm
28
what are some practical difficulties of working with actinoids
``` radioactive toxic v small quantities many isotopes are unstable causes unwanted chemical reactions ```
29
what are the 2 techniques used to overcome practical problems with working with actinoids
tracer techniques | ultra microchemical techniques
30
what are tracer techniques
use v small conc (10-12M) doped into non radioactive substance monitor radioactivity trace what happened to An
31
what are ultra microchemical techniques
v small volumes used at normal conc | done under microscope
32
how many f orbitals per shell
7
33
how many angular nodes does z3 have
0
34
how many angular nodes does yz2 have
1
35
how many angular nodes does z(x2-y2) have
2
36
how many angular nodes does x(x2-3y2) have
3
37
how does the electronic configuration of Ln3+ ions change
fills sequentially
38
what are the anomalies in the electronic configurations of Ln atoms
La - fills 5d1 not 4f1 Ce - fills 5d1 4f1 not 4f2 Gd- fills 4f7 5d1 to maintain half filled shell
39
which Ln can form 4+ and why
Ce4+ - stable as 4f0
40
which 2 Ln elements have stable 2+ ions and why
Yb2+ - forms 4f14 | Eu2+ - forms 4f7
41
how does the electronic figuration of An3+ go
sequentially as with Ln3+
42
what is notable about the electronic configuration of early An atoms
6d1 is filled instead of 5f up to Pu
43
what is notable about the electronic configuration of Lr
7p is more stable than 6d due to relativistic effects
44
why do some f elements experience relativistic effects
as charge density increase the speed of core electrons increases to stay in orbit - for late f elements this is near the speed of light
45
what is the formula of mass at high velocity
m = m0/root(1-(v/c))
46
what is the formula for the bohr radius
a0 = 4piE0(h2/me2)
47
what is the relationship between bohr radius and mass
as mass increases bohr radius increases
48
what is the effect of relativistic effects
s and p contract - increases shielding | f and d expand - closer in energy
49
why are early An elements similar to TMs
5f and 6d can bond as they are less sheilded
50
what is the coordination of Ln atoms in the metallic state
12 coordinated
51
what is the general trend of metallic radii across the period
radius decreases right to left
52
what are the 2 exceptions to the generic trend of metallic Ln atoms atomic radius
Eu and Yb
53
why are Eu and Yb larger when in a metal
they exist as 2+ ions in electrons whereas the rest exist as 3+ they are 2 plus becasue full and half filled f shells are stable
54
what is the trend of ionic radii for 3+ Ln ions
decreases left to right across period
55
what is the trend for metallic radii for An
decreases Ac-Np (similar to TM) | decreases from higher value Am-Cf
56
what is the trend is ionic radius for 3+/4+ ions
gradually decrease across period | 3+>4+
57
why are the first and second ionisation energies constant for Ln
it refers to the removal of 2 s electrons
58
what are the exceptions for the trend for the 3rd ionisation energies how do they relate to the rest
larger for Eu and Yb as they are stabilised as 2+ ions due to filled and half filled f sub shells
59
why is the 4th ionisation energy so high for La
the La3+ ion is a xenon configuration
60
why are the 4th ionisation energies for Ce and Tb low
they have f0 and f7 configuration for 4+ ions
61
why is the standard energy of reduction almost constant across the Ln series
as ionisation potential increases ^hyd increases due to increased ionic radius
62
what is the general trend for hydration enthalpies across the series
gradually increase (get more negative) across the series
63
what is the formula for calculating hydration enthalpy
^hyd= z^2/r
64
how does the stability of An3+ change across the series
increases left to right
65
which An elements can have oxidation states of 2,3,4,5 and 6
U, Np, Pu
66
what is the highest ox state for Ac
3
67
what is the most stable ox state for Ln elements
3
68
at what pH can Ce4+ undergo hydrolysis
0
69
what are 2 key features of An4+ ions
high charge density | strongly bronsted acidic
70
how is the rate of hydrolysis linked to charge density
as charge density increases, rate of hydrolysis decreases
71
what ions can An5+/6+ form
actinyl ions ([AnO2]+), [AnO2]2+
72
what elements are the 5 and 6 ox states important for
U, Np, Pu, Am
73
what is the evidence for 6p(z)5f(z3) hybridisation
short An-O distance | IR absorbtion at 930cm-1 (O-U-O)
74
which orbitals in An can interact with 2p in oxygen and why
6d and 5p | they are the correct distance from the U nucleus in the radial distribution diagram
75
is complex formation in aqueous solution endo or exothermic and why
endothermic as there is a very large ^hyd
76
how stable are aquo ions for Ln and An
they are very labile
77
how do ligands coordinate to an aquo complex
1. form an outsphere complex (attracted to near to complex) | 2. form an innersphere complex (replaces H2O around metal)
78
what is the order of increasing stability constants for inorganic ions
NO3-
79
what is the order of increasing stability constants for the halides
I->Br->Cl->F-
80
what is the formula for ^G of a complex
^G=-RTlnbeta
81
what is the formula for beta
B=[ML]/M^a*L*b
82
what is the usual value of ^rH
positive
83
what is the usual value for ^rS
large and positive | - cancels out large negative ^hyd
84
what type of ligands are normally required to form a stable complex
chelating ligands
85
give 3 examples of multidentate ligands
P3O10 5- EDTA 4- DTPA 5-
86
how does Ln change across the period and why
increases as r decreased
87
how does Ln be change as higher dentate ligands are used
Increases
88
why does the stabilty of DTPA complexes decrease after Py
DTPA isnt very flexible so isnt as stable on smaller elements
89
how do the kinetic of H2O exchange change across the series
first half follows Id mechanism | second half follows IA mechanism
90
why does the mechanism of H2O exchange change
In early elements they are 9 coord so can loose but not gain | in late elements they are 8 coord so can gain but not lose
91
when is H2O exchange fastestr
when energy different between 8 coord and 9 coord complexes is similar (middle of period)
92
what is the trend in the kinetics of forming oxalate complexes
faster for early elements
93
explain the trend in kinetics of Ln oxalate formation
there is a constant Id mechanism this is faster for the early elements as they are 9 coord so their bonds are longer and easier to break
94
what is the gadolinium break
an observation that gadolinium is often in the middle in trends as the 8 coord and 9 coord complexes are of similar energy
95
what do good donors tend to contain
acidic oxygens nitrogen donors sulfonic acid groups phenolic groups
96
give an example of a ligand that forms a kinetically inert lanthanide complex and why
schiff base (6N in macrocycles) completely surrounds metal
97
what does kinetically inert mean
cannot be formed in water as not thermodynamically stable but if formed then added to water there is no easy route to break them down
98
describe the coordination chemisty of the actinyl ion
equitorial positions are labile, axial are inert
99
decribe the trend of strength of complex formation for An ions
An4+>AnO2 2+> An3+> AnO2+
100
how does Pu(IV) work as a poison
similar charge density to Fe(III) so can fill iron stores - disrupts iron chemistry - releases radiation
101
what are the ligand requirements of a sequestering agent
non toxic | stable and soluble at physiological pH
102
what are the 2 geometries for 6 coordinate complexes
octahedral | trigonal prism
103
what is the known geometry of a 7 coordinate complex
pentagonal bipyramidal
104
what are the 2 known geometries for 8 coordinate complexes
cube | square antiprism
105
what is the geometry for a 9 coord complex
tricapped prism
106
what is the geometry for a 12 coord complex
icosahedron
107
what is a hepaleptic complex
complexes with multiple ligand types
108
what are the 2 common classes of neutral oxygen donors
polyethers | phosphine oxides/ phosphates
109
how does bonding with a metal ion vary for 15-c-5, tetraglyme and 18-c-6
15-c-5 sits under the metal ion as the cavity is not large enough to fit the ion inside tetraglyme and 18-c-6 fit around the metal ion well
110
how does logB change across series for tetraglyme
decreases as the ions get smaller do to steric hinderance of Me groups
111
why does 18-c-6 have a greater stability constant than 15-c-5
more donors present
112
why is 18-c-6 more stable for early Ln
better fit around metal
113
how do stabilities of cyclic and acyclic compounds compare
cyclic ligands are more stable than acyclic
114
how does 18-c-6 complex with the actinyl ion
has to distort to fit well | actinyl ions are small
115
describe the lewis acidity of phosphine oxides and phosphates
strong lewis bases
116
what are the 3 main types of neutral nitrogen donors
aliphatic amines aromatic N donors schiff base macrocycles
117
how do stability constants for aromatic amines vary across series
increases as M-L bond length decreases
118
how do the stability constants of aliphatic amines change as more N donors are added
increase
119
what complex will form in the reaction LnX3 + ligands ->
LnLx if X is weakly coordinating | LnX3Lx if X is strongly coordinating
120
why can naphthyridine have a high coordination number
has small bite angle
121
what happens in a schiffs base reaction
2 x 2,6-diketopyridine is attacked by 2x en to form a cyclic structure which wraps around metal ligand
122
how can An3+ ligands be separated from Ln3+ ligands
use BTBP ligand - N is enhanced due to alpha effect | binds more strongly to Am/Cm than to Eu
123
give examples of anion O donors
acac (B-diketonates) alkoxides phenoxides
124
what 3 properties of B-diketonates can be tuned
solubility volatility lewis acidity
125
what is the least sterically demanding B-diketonate
cannot cover coordination sphere for La3+ | fits Yb3+
126
how are B-diketonate complexes formed
remove of proton on B-oxygen with bases | reaction with MXn
127
give some properties of B-diketonates
Insoluble in water | reasonably volatile
128
what is a use of B-ketonates
in MOCVD | metal organic chemical vapour deposition
129
how do the structures of alkoxide complexes changw with ligand size
small - trimers medium - dimers large - monomers
130
what are the expections to the common rule that Ln3+ is the standard charge
Ce4+ Eu2+ Yb2+
131
how do anionic bonds vary to neutral bonds
anionic bonds are shorter
132
what are the main type of anionic N ligands
silyl amides
133
what are 2 key features of silyl amides
very large | stabilise low coordination numbers
134
what are 2 reactions that silyl amide complexes can undergo
ligand substitution with phenoxide | adduct formation with phosphine oxides
135
what structure is formed when silyl amides are involved in forming complexs with Ln2+
[Ln(N(SiMe2)2L2]
136
what 3 actinides are silyl amides known to complex with
U, Np, Pu