24 - transition elements Flashcards
(145 cards)
1
Q
what is a d block element
A
element where highest energy electron is in the d subshell
2
Q
what are some general properties of metals
A
metallic
high m.p / b.p
shiny
conduct electricity + heat
3
Q
what are the exceptions to the redox rules
A
Cr
Cu
4
Q
what is a transition metal
A
d block elements that form at least 1 ion with a partially filled d-orbital
5
Q
which d block elements are not transition metals
A
scandium + zinc
6
Q
why is scandium not a transition metal
atomic number - 21
A
does not form an ion with a partially filled d orbital - has an empty d orbital
7
Q
why is zinc not a transition metal
atomic number - 30
A
does not form an ion with a partially filled d orbital - has a full d orbital
8
Q
what are the properties specific to transition metals
A
form ions with variable oxidation states
forms coloured compounds
act as catalysts
9
Q
what is the oxidation state that all transition metals have
A
+2
10
Q
colour of potassium dichromate
A
bright orange
11
Q
colour of Cobalt (II) chloride
A
pink purple
12
Q
colour of Cr04
A
yellow
13
Q
how do transition elements form coloured compounds
A
linked to partially filled d orbitals
14
Q
what happens if you dissolve a coloured compound
A
make coloured solutions
15
Q
benefits + risks of using transition metals as catalysts
A
Benefits – reduces energy usage / lower costs
Risks – toxicity of many transition metals
16
Q
examples of reactions where the transition metal is a heterogenous catalyst
A
17
Q
examples of reactions where the transition metal is a heterogenous catalyst
A
18
Q
what is a complex ion
A
Consists of a central metal ion with one or more molecules / charged ions (ligands) bound to it by dative covalent bonds
19
Q
what are complex ions formed from
A
Formed by d-block elements
+ other elements – Aluminium
20
Q
what is a ligand
A
Molecule / ion that donates a pair of electrons to a central metal atom by coordinate / dative covalent bonding
21
Q
what is needed for something to be a ligand
A
Lone pairs needed
22
Q
what are some neutral ligands
A
water / ammonia
23
Q
what are some charged ligands
A
halide ions / CN- / hydroxide
24
Q
how is a complex ion written out
A
25
what is the coordination number
Number of coordinate bonds made to the central metal atom
26
shape / bond angle / examples of coordination number 6
Octahedral
Bond angle – 90
Hexaaqua complexes
27
draw a 3D shape of a complex ion with a coordination number of 6
28
what are the shapes that arise from a coordination number of 4
tetrahedral and square planar
29
bond angle + example for tetrahedral
Bond angle – 109.5
Tetrachloro complexes
30
bond angle for square planar
90
31
which metals make square planar complexes over tetrahedral
tends to occur for transition metals with 8 d electrons
Platinum (II), palladium (II) and gold (III)
32
draw a tetrahedral complex
33
draw a square planar complex
34
what is a monodentate ligand
ligand that is able to donate one pair of electrons to a central metal atom
35
what is a bidentate ligand
able to donate 2 pairs of electrons to a central metal atom
36
what are 5 examples of monodentate ligands
37
examples of bidentate ligands
38
what complexes show cis-trans isomerism
4 coordinate + 6 coordinate complex ions with different monodentate / bidentate ligands
39
which complexes show both cis trans and optical isomerism
6 coordinate complexes with monodentate and bidentate ligands
40
what needs to be for a square planar complex to show cis trans isomerism
have no more than 2 identical ligands
41
cis square planar
two identical ligands are adjacent to eachother - 90 degrees apart
42
trans square planar
two identical ligands are opposite each other - 180 degrees apart
43
draw the cis + trans isomers of [Pd(NH3)2(Cl)2]
44
what needs to be for an octahedral monodentate complex to show cis trans isomerism
contain 4 of one type + 2 of another type of ligand
45
cis monodentate octahedral
two identical ligands are adjacent to each other - 90 degrees
46
trans monodentate octahedral
two identical ligands are opposite to each other - 180 degrees
47
draw the cis + trans isomers of [Co(NH3)4(Cl)2]+
48
what needs to be for an octahedral bidentate complex to show cis trans isomerism
contain 2 bidentate ligands + 2 identical monodentate ligands
49
cis bidentate octahedral
two identical monodentate ligands adjacent to each other - 90 degrees
50
trans bidentate octahedral
two identical monodentate ligands are opposite to each other - 180 degrees
51
draw cis + trans [Co(NH3CH2CH2NH2)2 (Cl)2]+
52
do square planar complexes show optical isomerism
no
53
do octahedral complexes show optical isomerism
yes
54
what needs to be for a octahedral complex to show optical isomerism
ONLY in cis isomers with 2 or more bidentate ligands
55
can trans octahedral show optical isomerism
no
56
can cis octahedral show optical isomerism
yes
57
draw the optical isomers of [Co(NH3CH2CH2NH2)2 (Cl)2]+
remember only cis
58
draw optical isomers of [Ni(NH3CH2CH2NH2)3]2+
59
what is ligand substitution
Where 1 ligand is exchanged for another
60
what does ligand substitution normally cause
colour change
61
what occurs when ligand exchange happens between two similar sized ligands
If ligands similar size – coordination number of complex ion or shape does not change
62
what are some examples of similar sized ligands
H2O
NH3
63
what colour is a solution of [Cr(H2O)6]3+
violet solution
64
write out the reaction between [Cr(H2O)6]3+ and NH3
65
describe the observations for the reaction between [Cr(H2O)6]3+ and NH3
colour change from a violet solution to a purple solution
66
does the shape of the metal complex change when you react [Cr(H2O)6]3+ and NH3
no - both octahedral as they are similar sized ligands
67
what colour is [Cr(NH3)6]3+
purple solution
68
what colour is [Cr(H2O)5SO4]+
green solution
69
write out the reaction between [Cr(H2O)5SO4]+ and NH3
70
describe the observations for the reaction between [Cr(H2O)5SO4]+ and NH3
colour change from green to purple
71
does the shape of the metal complex change when you react [Cr(H2O)5SO4]+ and NH3
no - both octahedral - as similar sized ligands
72
what are the products in the reaction between [Cr(H2O)5SO4]+ and NH3
73
does copper undergo ligand exchange
yes BUT only partial exchange
74
what colour is [Cu(H2O)6]2+
pale blue solution
75
write out the equation when [Cu(H2O)6]2+ reacts with ammonia
76
draw [Cu(H2O)6]2+
77
describe the observations for the reaction between [Cu(H2O)6]2+ and ammonia
pale blue to dark blue solution
78
does the shape of the metal complex change when you react [Cu(H2O)6]2+ and ammonia
no - both octahedral as they are similar sized ligands
79
what are the products in the reaction between [Cu(H2O)6]2+ and ammonia
80
draw [Cu(NH3)4(H2O)2]2+
81
what happens if a small uncharged swapped for large charged ligand (or vice versa)
change in shape + coordination number
82
write out the reaction between [Cu(H2O)6]2+ and chloride ions
83
describe the observations that occur when you react [Cu(H2O)6]2+ and chloride ions
pale blue to yellow
84
does the shape of the metal complex change when you react [Cu(H2O)6]2+ and chloride ions
yes - because Cl- are smaller
85
what is the shape change when you react [Cu(H2O)6]2+ and chloride ions
[Cu(H2O)6]2+ = tetrahedral
[Cu(Cl4)]2- = tetrahedral
86
where do the chloride ions come from in the reaction between [Cu(H2O)6]2+ and chloride ions
concentrated HCl
87
what are the products the reaction between [Cu(H2O)6]2+ and chloride ions
88
draw both [Cu(H2O)6]2+ and [Cu(Cl4)]2-
89
how does ammonia form hydroxide ions
NH3 + H2O ⇌ NH4+ + OH-
90
Why does the solution of aqueous copper (II) ions reacting with chloride ions turn green as the reaction proceeds?
The yellow and blue solutions mixing gives a green colour.
91
What is formed when chromium(III) potassium sulphate is dissolved in water?
what’s the formula and colour?
The complex ion [Cr(H2O)6]3+ is formed.
A pale purple solution.
92
What is formed instead when only chromium(III) sulphate is dissolved in water?
what’s the formula and colour?
The complex ion [Cr(H2O)5SO4]+ is formed.
A green solution.
93
what happens if ammonia / sodium hydroxide added to aqueous transition metal complexes dropwise
coloured precipitates of insoluble transition metal hydroxide forms
94
what is a precipitation reaction
two aqueous solutions that contain ions react together to form an insoluble ionic solid
95
are precipitation reactions reversible
yes
precipitates can be re-dissolved by adding acid
96
when you add ammonia / sodium hydroxide to these metal complexes what happens first
it will initially form the metal hydroxide
97
What colour is Fe2+
pale green solution
98
what are the observations when you add dropwise ammonia / sodium hydroxide to Fe2+
pale green solution to a green ppt (turns orange on standing)
99
what is the green ppt when you add dropwise ammonia / sodium hydroxide to Fe2+
Fe(OH)2
100
write out the reaction between dropwise ammonia / sodium hydroxide and Fe2+
101
why does Fe(OH)2 turn orange on standing
gets oxidised to Fe3+
102
what colour is Fe3+
pale yellow solution
103
what are the observations when you add dropwise ammonia / sodium hydroxide to Fe3+
pale yellow solution to orange brown ppt
104
what is the orange brown ppt
Fe(OH)3
105
write out the reaction between dropwise ammonia / sodium hydroxide and Fe2+
106
describe the observations when you react [Cu(H2O)6]2+ with dropwise ammonia vs excess ammonia
107
describe the observations when you react [Cr(H2O)6]3+ with dropwise ammonia vs excess ammonia
108
describe the observations when you react [Cr(H2O)6]3+ with dropwise sodium hydroxide vs excess sodium hydroxide
109
Describe the precipitation reaction of Fe2+ with OH and what is the equation?
Fe2+ + 2OH- = Fe(OH)2 (s)
pale green solution to green precipitate
110
Describe the precipitation reaction of Fe3+ with OH and what is the equation?
Fe3+ + 3OH- = Fe(OH)3 (s)
pale yellow to orange-brown precipitate
111
Describe the precipitation reaction of Mn2+ with OH and what is the equation?
Mn2+ + 2OH- = Mn (OH)2 (s)
pale pink solution to light brown precipitate
112
Describe the precipitation reaction of Cr3+ with OH and what is the equation?
Cr3+ (aq) + 3OH- (aq) = Cr(OH)3 (s)
violet solution to green precipitate
113
Describe the precipitation reaction of Cu2+ with NaOH and what is the equation?
Cu2+(aq)+2NaOH(aq)→ Cu(OH)2(s)+2Na+(aq)
pale blue solution to a blue precipitate of copper(II) hydroxide.
114
How do Cr3+ react with an excess of aqueous NaOH?
the hydroxide of Cr 3+ does dissolve in excess NaOH
Cr3+ + NaOH (aq)= Cr(OH)3 (s)
excess NaOH=[Cr (OH)6] 3-
115
Cu2+
appearance of aqueous solution
observations with dropwise NaOH / NH3
observations with excess NH3
observations with excess NaOH
116
Fe2+
appearance of aqueous solution
observations with dropwise NaOH / NH3
observations with excess NH3
observations with excess NaOH
117
Fe3+
appearance of aqueous solution
observations with dropwise NaOH / NH3
observations with excess NH3
observations with excess NaOH
118
Mn2+
appearance of aqueous solution
observations with dropwise NaOH / NH3
observations with excess NH3
observations with excess NaOH
119
Cr3+
appearance of aqueous solution
observations with dropwise NaOH / NH3
observations with excess NH3
observations with excess NaOH
120
what is haemoglobin
A metalloprotein
121
what is the structure of haemoglobin
Central Fe2+ metal ion
Multidentate haem ring = 4 nitrogen’s, forming 4 dative covalent bonds (in square planar configuration)
Also forms a dative bond with the protein globin
Finally, dative bond with O2 or H2O (ligands)
Coordination number 6, octahedral overall
122
how is oxyhaemoglobin
* Binds reversibly with oxygen via ligand exchange
123
how is the dative bond between oxygen and Fe2+ advantageous
as it releases O2 when needed
124
why is carbon monoxide dangerous
Carbon monoxide has a lone pair of electrons on its carbon – can act as a ligand
much stronger dative bond forms between CO and Fe2+ in the haem group than O2
Any CO breathed in, will permenantly replace O2, ligand exchange
Forms carboxyhaemoglobin
125
write out both equations of haemoglobin + oxygen / carbon monoxide
Haemoglobin + oxygen ⇌ oxyhaemoglobin
Haemoglobin + carbon monoxide → carboxyhaemoglobin
126
what colour is (MnO4)-
purple
127
colour change when fe3+ reacts with I-
orange brown Fe3+ reduced to pale green fe2+
pale green obscured by the oxidation of I- to I2 - brown colour
128
conditions for oxidation of Fe2+
H+/MnO4-
129
conditions for reduction of Fe3+
I–
130
write out equation for oxidation of fe2+ AND colour changes
131
write out the equation for the reduction of Fe3+ AND colour change
132
what colour are dichromate ions
orange
133
what colour are chromium (III) ions
green
134
conditions for reduction of dichromate ions
Zn/H+,
135
write out the equation for the reduction of dichromate ions AND colour change
136
what happens if an excess if zinc is added to dichromate ions
chromium 3+ ions reduced further to chromium 2+
137
what colour is chromium 2+
pale blue
138
write out the equation for the reduction of chromium in excess zinc AND colour change
139
conditions for oxidation of Cr3+
hot alkaline hydrogen peroxide
hydroxide ions
140
write out the equation of the oxidation of Cr3+
141
conditions for reduction of Cu2+
I- (excess)
142
write out the equation for reduction of Cu2+ AND colour change
143
what happens in aqueous conditions for copper
Cu+ readily disproportionates.
144
compound where Cu has oxidation state 1
Cu2O - copper oxide
145
example of disproportionation of Cu+ ions
Copper oxide reacts with hot dilute sulfuric acid
