Transition Elements Flashcards
1
Q
Where is the d-block elements?
A
Block of elements in the middle of the periodic table
2
Q
What block are the transition elements in?
A
d-block
3
Q
What is the definition of a transition element?
A
A d-block element that can form at least one stable ion with a partially filled d-subshell
4
Q
How many electrons can a d-subshell have?
A
10
5
Q
For period 4, what are the only 2 elements in d-block that aren’t transition metals?
A
Zinc and Scandium
6
Q
What are the 2 rules that are followed to help with figuring out the electron configuration?
A
Electrons fill up the lowest energy subshells first
Electrons fill orbitals singly before they start sharing
7
Q
Why does the 4s subshell fill up before the 3d subshell?
A
The 4s subshell has a lower energy than the 3s subshell
8
Q
3s orbitals are filled singly first before they start to double up, what are the 2 exceptions?
A
- Chromium prefers to have one electron in each orbital of the 3d subshell and just one in the 4s subshell- giving it more stability
- Copper prefers to have a full 3d subshell and just one electron in the 4s subshell - making it more stable
9
Q
What are subshells made of?
A
Orbitals
10
Q
What are orbitals?
A
A region of a subshell that can contain a maximum of 2 electrons
11
Q
What charge of ion do transition metals form?
A
Positive metal ions
12
Q
Why are scandium (Sc) and zinc (Zn) not transition elements?
A
Their stable ions don’t have partially-filled d-subshells, so don’t have the same chemical properties as transition metals
13
Q
What ion does scandium form, and why does this not make it a transition element?
A
Sc3+, meaning it doesn’t have any electrons in the d-subshell
14
Q
What ions does zinc form, and why does this not make it a transition element?
A
Zn2+, meaning it has a full d-subshell
15
Q
What are the 5 special chemical properties that transition metals have?
A
- They can form complex ions
- They form coloured ions
- They’re good catalysts
- They can exist in various different oxidation states
16
Q
What 2 ions does tin form, and what are their corresponding oxidation states?
A
Ti2+ = oxidation state of +2 Ti3+ = oxidation state of +3
17
Q
What colour is Ti2+?
A
Violet
18
Q
What colour is Ti3+?
A
Purple
19
Q
What ions does vanadium form, and what are their corresponding oxidation states?
A
V2+ = oxidation state of +2
V3+ = oxidation state of +3
VO 2+ = oxidation state of +4
VO2 + = oxidation state of +5
20
Q
What colour is V2+?
A
Violet
21
Q
What colour is V3+?
A
Green
22
Q
What colour is VO 2+?
A
Blue
23
Q
What colour is VO2 +?
A
Yellow
24
Q
What ions does chromium form, and what are their corresponding oxidation states?
A
Cr3+ = oxidation state of +3
Cr2O7 2- = oxidation state of +6
25
What colour is Cr3+?
Green
26
What colour is Cr2O7 2-?
Orange
27
What ions does manganese form, and what are their corresponding oxidation states?
Mn2+ = oxidation state of +2
MnO4 2- = oxidation state of +6
MnO4 - = oxidation state of +7
28
What colour is Mn2+?
Very pale pink/colourless
29
What colour is MnO4 2-?
Green
30
What colour is MnO4 -?
Purple
31
What ions does iron form, and what are their corresponding oxidation states?
```
Fe2+ = oxidation state of +2
Fe3+ = oxidation state of +3
```
32
What colour is Fe2+?
Pale green
33
What colour is Fe3+?
Yellow
34
What ion does cobalt form, and what is its corresponding oxidation state?
Co2+ = oxidation state of +2
35
What colour is Co2+?
Pink
36
What ion does nickel form, and what is its corresponding oxidation state?
Ni2+ = oxidation state of +2
37
What colour is Ni2+?
Green
38
What ion does copper form, and what is its corresponding oxidation state?
Cu2+ = oxidation state of +2
39
What colour is Cu2+?
Pale blue
40
Why do transition metals have variable oxidation states?
The energy levels of 4s and 3d subshells are very close to one another, so different numbers of electrons can be lost or gained with fairly similar amounts of energy
41
Why do transition metals make good catalysts?
They can change oxidation states by gaining or losing electrons from their d-orbitals. This means they can transfer electrons to speed up reactions. They are also good at absorbing substances onto their surfaces to lower the activation energy of the reaction
42
Give an example of a reaction where iron is used as the catalyst?
Haber process
43
Give an example of a reaction where copper(II) sulfate is used as the catalyst?
Reaction between zinc and acids
44
Give an example of a reaction where manganese(IV) oxide is used as the catalyst?
The decomposition of hydrogen peroxide
45
Why are catalysts good for industry and the environment?
They allow reactions to happen faster and at lower temperatures and pressures, reducing the amount of energy needed
46
What causes transition metals to have special chemical properties?
The partially filled d-subshell
47
What is a complex ion?
A metal ion surrounded by coordinately bonded ligands
48
What is a ligand?
An atom, ion or molecule that donates a pair of electrons to a central metal ion in a complex ion
49
What is a coordinate bond (dative covalent bond)?
A covalent bond in which both electrons in the shared pair come from the same atom, ion or molecule
50
What must a ligand have?
At least one lone pair
51
Why does a ligand need at least one lone pair?
So it has electrons to use to form a coordinate bond?
52
In a complex ion, where do the electrons come from for the coordinate bond?
The ligand
53
What is a monodentate?
A ligand that can only form one coordinate bond
54
Give an example of a monodentate
Ammonia
55
What is a multidentate?
A ligand that can form more than 1 coordinate bond
56
What is a bidentate?
A multidentate ligand that can form 2 coordinate bonds
57
What does the shape of a complex ion depend on?
The coordination number
58
What is the coordination number?
The number of coordinate bonds that are formed with the central metal ion
59
What does a complex ion's coordination number depend on?
The number of bonds formed with the ligands - not the number of ligands
60
What is the coordination number of a complex ion with 3 bidentate ligands?
Coordination number = 6 because 3 ligands that each form 2 coordinate bonds (2x3=6)
61
What is the shape of a complex ions with 6 coordinate bonds, and what is the bond angle?
Octahedral shape (all bond angles are 90°)
62
For coordinate bonds, what does a wedge-shaped arrow pointing to the central metal ion represent in a diagram?
Represents bonds coming towards you
63
For coordinate bonds, what does a dashed arrow pointing to the central metal ion represent in a diagram?
Represents a bond sticking out behind the molecule
64
What is the shape of a complex ion with 4 coordinate bonds?
Tetrahedral shape
65
What is the bond angle of a 3D complex ion structure with 4 coordinate bonds?
109.5°
66
What is the bond angle of complex ion structure with 4 coordinate bonds that form a square planar shape?
90°
67
Give an example of a tetrahedral complex ion which has bond angles of 90°?
Cisplatin
68
Why are the bond angles in cisplatin 90°?
Because the 4 coordinate bonds form a square planar shape
69
What is cisplatin?
An anti-cancer drug
70
In the complex ion structure [Fe(en)3]3+, what does the 'en' stand for?
One ethane-1,2-diamine ligand
71
Give an example of a bidentate ligand
ethane-1,2-diamine ligand
72
Give an example of an octahedral complex ion
[Fe(H2O)6]2+
73
What are stereoisomers?
Molecules with the same structural formula but a different orientation of their bonds in space
74
What is an optical isomer?
An isomer of a complex ion, where an ion can exist as 2 non-superimposable mirror images
75
What shape of complex ion does optical isomerism occur?
In octahedral complexes with 3 bidentate ligands attached to the central ion
76
What are optical isomers known as?
Enantiomers
77
Describe what the trans isomer looks like for a square planar complex ions with 2 pairs of ligands?
When 2 paired ligands are directly opposite each other
78
Describe what the cis isomer looks like for a square planar complex ions with 2 pairs of ligands?
When 2 paired ligands are directly opposite each other
79
What is cisplatin made of?
A complex of platinum (II) with 2 chloride ions and 2 ammonia molecules in a square planar shape
80
What is cancer caused by, and why does cisplatin help?
Cancer is caused by cells in the body dividing uncontrollably and forming tumours. Cisplatin helps because it prevents cancer cells from reproducing
81
How does cisplatin stop cancer cells from reproducing?
When a cells divides, it has to first replicate its DNA by unwinding the 2 strands of the double helix. Cisplatin easily loses its chloride ligands through a displacement reaction and forms coordinate bonds with nitrogen atoms in the DNA molecule. This prevents the 2 strands from unwinding, so the cell can no longer divide
82
What does the trans isomer look like for an octahedral complex with 4 ligands of one type and 2 ligands of another type?
If the 2 odd ligands are opposite each other
83
What does the cis isomer look like for an octahedral complex with 4 ligands of one type and 2 ligands of another type?
If the 2 odd ligands are next to each other
84
What is a downside with using cisplatin to stop cancer?
It stops normal cells from replicating, causing hair loss, a weaker immune system and could cause damage to the kidneys
85
What is ligand substitution?
When 1 ligand is swapped for another ligand
86
What does ligand substitution normally cause?
A colour change
87
What happens when ligand substitution occurs of similarly sized ligands?
The coordination number of the complex ion doesn't change, and neither does the shape
88
What happens if an H2O ligand is swapped for a NH3 ligand?
Because they're similar sizes, the shape and coordination number doesn't change, but the colour does change
89
What happens when ligand substitution occurs of different sized ligands?
A change in coordination number and shape occurs
90
What is partial ligand substitutuion?
When not all of the ligands are substituted
91
For predicting the outcome of unusual reactions, what can be said about H2O, NH3, OH-, CN- and Cl- ligands?
H2O, NH3, OH-, CN- are all similar size but Cl- ions are a lot larger
92
What is Haemoglobin?
A protein found in the blood that helps to transport oxygen around the body
93
What is Haemoglobin made of?
Fe2+ ions which are hexa-coordinated to six lone pairs
94
What is the Haem part of Haemoglobin made up of?
4 lone pairs that come from nitrogen atoms form a circle around the Fe2+
95
What is porphyrin?
A multidentate ligand made up of the molecule that the 4 nitrogen atoms are a part of in haemoglobin
96
What shape structure is formed around the Fe2+ ion in haemoglobin?
An octahedral shape
97
What 3 things make up the octahedral shape of haemoglobin?
A porphyrin ring
A globin (protein)
Either a water or oxygen molecule
98
What is the haemoglobin complex called when water bonds to an Fe2+ ion?
Deoxyhaemoglobin
99
What is the haemoglobin complex called when oxygen bonds to an Fe2+ ion?
Oxyhaemoglobin
100
How does haemoglobin transport oxygen around the body?
An oxygen molecules bond to form a haemoglobin complex. The oxygen is then transported to where it's needed, at which point the oxygen is swapped for a water
101
Describe the process, involving haemoglobin, which happens in the lungs
In the lungs, where the oxygen concentration is high, water ligands are substituted for oxygen molecules to form oxyhaemoglobin, which is carried around the body in the blood
102
What happens when the oxyhaemoglobin reaches the place where oxygen is needed?
The oxygen molecules are exchanged for a water molecule. The haemoglobin then travels back to the lungs where the whole process starts again
103
What happens to the haemoglobin when carbon monoxide is inhaled?
The haemoglobin exchanges its oxygen ligand for a carbon monoxide ligand, forming carboxyhaemoglobin.
104
Why is inhaling carbon monoxide bad?
Carbon monoxide forms a very strong bond with an Fe2+ ion in haemoglobin, so doesn't exchange with a water of oxygen molecule. This means that the particular haemoglobin can't transport oxygen around the blood anymore
105
What does carbon monoxide poisoning do and what are the health affects?
It starves the organs of oxygen causing headaches, dizziness, unconsciousness and death if not treated
106
What is the colour of oxyhaemoglobin?
Red, which is why red blood cells are red
107
What is the product when you mix an aqueous solution of transition metal ions with aqueous sodium hydroxide or aqueous ammonia?
You get a coloured hydroxide precipitate
108
What is the notation for precipitation reactions of aqueous solution of transition metal ions?
M^(n+) ( you leave out any water ligands)
109
In water, what does sodium hydroxide dissociate into?
Na+ and OH- ions
110
What is a precipitate?
A solid formed in a solution
111
What is the equation for the reaction between an iron ion (Fe2+) and aqueous sodium hydroxide? Include the water ligands
[Fe(H2O)6]2+ + 2OH- ---> Fe(OH)2(H2O)4 + 2H2O
The OH- ions don't replace the water ligands, they just take one H+ ion to form an H2O molecule and then the water ligand turns into OH- ligand
112
What is the equation for the reaction between an iron ion (Fe2+) and aqueous ammonia? Include the water ligands
[Fe(H2O)6]2+ + 2OH- ---> Fe(OH)2(H2O)4 + 2NH4+
113
What is the colour change in the reaction between an aqueous iron ion (Fe2+) and aqueous ammonia or aqueous sodium hydroxide?
Pale green ---> Darker green precipitate
114
What is the colour change in the reaction between an aqueous copper ions ( Cu(II) ) and aqueous ammonia or aqueous sodium hydroxide?
Pale blue ---> Blue precipitate
115
What is the colour change in the reaction between an aqueous manganese ions ( Mn(II) ) and aqueous sodium hydroxide or aqueous ammonia?
Pale pink ---> Pink/Buff (sandy colour) precipitate
116
What is the colour change in the reaction between an aqueous iron ions ( Fe(III) ) and aqueous sodium hydroxide or aqueous ammonia?
Yellow ---> Orange precipitate
117
What is the colour change in the reaction between an aqueous chromium ions ( Cr(III) ) and aqueous sodium hydroxide or aqueous ammonia?
Green ---> Grey-green precipitate
118
Write the equation for copper (II) reacting with aqueous sodium hydroxide (include water ligands)
[Cu(H2O)6]2+ + 2OH- ---> Cu(OH)2(H2O)4 + 2H2O
119
Write the equation for manganese (II) reacting with aqueous sodium hydroxide (include water ligands)
[Mn(H2O)6]2+ + 2OH- ---> Mn(OH)2(H2O)4 + 2H2O
120
Write the equation for copper (II) reacting with aqueous ammonia (include water ligands)
[Cu(H2O)6]2+ + 2NH3 ---> Cu(OH)2(H2O)4 + 2NH4+
121
Write the equation for manganese (II) reacting with aqueous ammonia (include water ligands)
[Mn(H2O)6]2+ + 2NH3 ---> Mn(OH)2(H2O)4 + 2NH4+
122
Write the equation for iron (III) reacting with aqueous sodium hydroxide (include water ligands)
[Fe(H2O)6]3+ + 3OH- ---> Fe(OH)3(H2O)3 + 3H2O
123
Write the equation for chromium (III) reacting with aqueous sodium hydroxide (include water ligands)
[Cr(H2O)6]3+ + 3OH- ---> Cr(OH)3(H2O)3 + 3H2O
124
Write the equation for chromium (III) reacting with aqueous ammonia (include water ligands)
[Cr(H2O)6]3+ + 3NH3 ---> Cr(OH)3(H2O)3 + 3NH4+
125
Write the equation for iron (III) reacting with aqueous ammonia (include water ligands)
[Fe(H2O)6]3+ + 3NH3 ---> Fe(OH)3(H2O)3 + 3NH4+
126
When writing precipitation reactions for transition elements, what's the easy way to remember how to write reactions involving metal ions with a charge of 2+ and 3+?
Metal ions with a 2+ charge form precipitates with 2 hydroxide ions
Metal ions with a 3+ charge form precipitates with 3 hydroxide ions
127
Why do transition metals exist in different oxidation states?
Because they can change oxidation state by gaining or losing electrons in redox reactions (also resulting in a colour change)
128
Describe the interconversion between Fe2+ and Fe3+ ions
Iron ions can lose or gain electrons to switch between the Fe2+ and Fe3+ states when appropriate oxidising or reducing agents are added to their solutions
129
Name an oxidising agent used for the interconversion of iron ions
Acidified potassium manganate (VII) solution
130
What is the full equation for the oxidation of Fe2+ to Fe3+ by Mn(VII) ions in acid solution?
Mn04- + 8H+ + 5Fe2+ ---> Mn2+ + 4H2O + 5Fe3+
131
What is the colour change for the oxidation of Fe2+ to Fe3+ by Mn(VII) ions in acid solution?
Fe2+ is pale green and Fe3+ is yellow
Pale green ---> Yellow
132
Name a reducing agent used for the interconversion of iron ions
Iodide solution
133
What is the full equation for the reduction of Fe3+ to Fe2+ by I- ions?
2I- + 2Fe3+ ---> 2Fe2+ + I2
134
What is the first colour change for the oxidation of Cr3+ to dichromate (VI) Cr2O7 2-?
Dark green ---> Yellow
135
What is the second colour change for the oxidation of Cr3+ to dichromate (VI) Cr2O7 2-?
Yellow ---> Orange
136
Why are there 2 colour changes in the oxidation of Cr3+ to dichromate (VI) Cr2O7 2-?
Because after the first colour change, sulfuric acid is added to the chromate (VI) solution to produce a dichromate (VI) solution
137
What is the oxidising agent used for the oxidation of Cr3+ to dichromate (VI) Cr2O7 2-?
Hydrogen peroxide solution
138
What is the reducing agent used in the reduction of dichromate (VI) Cr2O7 2- to Cr3+?
Acidified zinc
139
Describe the copper redox reactions
Cu2+ ions can be reduced to Cu+, giving an oxidation number change of +2 to +1
140
Describe the disproportionation reaction of Cu+ ions
Cu+ is unstable so spontaneously disproportionates - meaning copper is oxidised and reduced at the same time
141
Write the full equation for the disproportionation reaction of Cu+ ions
2Cu+ ---> Cu2+ + Cu
142
Describe how you can identify transition metal ions
Transition metal ions form coloured precipitates when NaOH is added. So to identify them, drop NaOH solution from a pipette and record the colour of the precipitate formed
143
For the test to identify transition metal ions, what colour is the precipitate of Cu2+ ions?
Blue
144
For the test to identify transition metal ions, what colour is the precipitate of Fe2+ ions?
Green
145
For the test to identify transition metal ions, what colour is the precipitate of Fe3+ ions?
Orange
146
For the test to identify transition metal ions, what colour is the precipitate of Mn2+ ions?
Pink / Buff (sandy colour)
147
For the test to identify transition metal ions, what colour is the precipitate of Cr3+ ions?
Grey-green
148
Describe the test for halide ions
Add nitric acid, followed by silver nitrate solution. If chloride, bromide or iodide ions are present then a precipitate will form
149
In the test for halide ions, what colour is the precipitate of AgBr (silver bromide)?
Cream
150
In the test for halide ions, what colour is the precipitate of AgCl (silver chloride)?
White
151
In the test for halide ions, what colour is the precipitate of AgI (silver iodide)?
Yellow
152
Describe the test for sulfates
Add a dilute strong acid followed by a few drops of barium nitrate solution to the unknown solution. If you get white precipitate it's barium sulfate, telling you that sulfate ions are present
153
Why do you add the dilute strong acid in the test for sulfates?
To make sure you don't get a false positive result, because carbonate and sulfite ions also form a white precipitate when reacted with barium nitrate. Adding the acid removes any carbonates or sulfites
154
Describe the test for carbonates
Add a dilute strong acid to the unknown solution. If carbonates are present then CO2 will be released. To see if any CO2 is produced, bubble any gas through limewater. If CO2 is present then the limewater will go cloudy
155
Describe the test for ammonium ions
Use a damp piece of red litmus paper. If there are ammonium ions present, the litmus paper will turn blue
