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A Level Chemistry Year 2 > Transition Elements > Flashcards

Transition Elements Flashcards

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1
Q

Where is the d-block elements?

A

Block of elements in the middle of the periodic table

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2
Q

What block are the transition elements in?

A

d-block

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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

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4
Q

How many electrons can a d-subshell have?

A

10

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5
Q

For period 4, what are the only 2 elements in d-block that aren’t transition metals?

A

Zinc and Scandium

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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

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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

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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
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9
Q

What are subshells made of?

A

Orbitals

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10
Q

What are orbitals?

A

A region of a subshell that can contain a maximum of 2 electrons

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11
Q

What charge of ion do transition metals form?

A

Positive metal ions

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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

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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

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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

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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
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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
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17
Q

What colour is Ti2+?

A

Violet

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18
Q

What colour is Ti3+?

A

Purple

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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

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20
Q

What colour is V2+?

A

Violet

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21
Q

What colour is V3+?

A

Green

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22
Q

What colour is VO 2+?

A

Blue

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23
Q

What colour is VO2 +?

A

Yellow

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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

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25
Q

What colour is Cr3+?

A

Green

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26
Q

What colour is Cr2O7 2-?

A

Orange

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27
Q

What ions does manganese form, and what are their corresponding oxidation states?

A

Mn2+ = oxidation state of +2
MnO4 2- = oxidation state of +6
MnO4 - = oxidation state of +7

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28
Q

What colour is Mn2+?

A

Very pale pink/colourless

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29
Q

What colour is MnO4 2-?

A

Green

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30
Q

What colour is MnO4 -?

A

Purple

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31
Q

What ions does iron form, and what are their corresponding oxidation states?

A 
Fe2+  = oxidation state of +2
Fe3+  = oxidation state of +3
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32
Q

What colour is Fe2+?

A

Pale green

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33
Q

What colour is Fe3+?

A

Yellow

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34
Q

What ion does cobalt form, and what is its corresponding oxidation state?

A

Co2+ = oxidation state of +2

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35
Q

What colour is Co2+?

A

Pink

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36
Q

What ion does nickel form, and what is its corresponding oxidation state?

A

Ni2+ = oxidation state of +2

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37
Q

What colour is Ni2+?

A

Green

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38
Q

What ion does copper form, and what is its corresponding oxidation state?

A

Cu2+ = oxidation state of +2

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39
Q

What colour is Cu2+?

A

Pale blue

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40
Q

Why do transition metals have variable oxidation states?

A

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

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41
Q

Why do transition metals make good catalysts?

A

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

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42
Q

Give an example of a reaction where iron is used as the catalyst?

A

Haber process

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43
Q

Give an example of a reaction where copper(II) sulfate is used as the catalyst?

A

Reaction between zinc and acids

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44
Q

Give an example of a reaction where manganese(IV) oxide is used as the catalyst?

A

The decomposition of hydrogen peroxide

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45
Q

Why are catalysts good for industry and the environment?

A

They allow reactions to happen faster and at lower temperatures and pressures, reducing the amount of energy needed

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46
Q

What causes transition metals to have special chemical properties?

A

The partially filled d-subshell

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47
Q

What is a complex ion?

A

A metal ion surrounded by coordinately bonded ligands

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48
Q

What is a ligand?

A

An atom, ion or molecule that donates a pair of electrons to a central metal ion in a complex ion

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49
Q

What is a coordinate bond (dative covalent bond)?

A

A covalent bond in which both electrons in the shared pair come from the same atom, ion or molecule

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50
Q

What must a ligand have?

A

At least one lone pair

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51
Q

Why does a ligand need at least one lone pair?

A

So it has electrons to use to form a coordinate bond?

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52
Q

In a complex ion, where do the electrons come from for the coordinate bond?

A

The ligand

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53
Q

What is a monodentate?

A

A ligand that can only form one coordinate bond

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54
Q

Give an example of a monodentate

A

Ammonia

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55
Q

What is a multidentate?

A

A ligand that can form more than 1 coordinate bond

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56
Q

What is a bidentate?

A

A multidentate ligand that can form 2 coordinate bonds

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57
Q

What does the shape of a complex ion depend on?

A

The coordination number

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58
Q

What is the coordination number?

A

The number of coordinate bonds that are formed with the central metal ion

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59
Q

What does a complex ion’s coordination number depend on?

A

The number of bonds formed with the ligands - not the number of ligands

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60
Q

What is the coordination number of a complex ion with 3 bidentate ligands?

A

Coordination number = 6 because 3 ligands that each form 2 coordinate bonds (2x3=6)

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61
Q

What is the shape of a complex ions with 6 coordinate bonds, and what is the bond angle?

A

Octahedral shape (all bond angles are 90°)

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62
Q

For coordinate bonds, what does a wedge-shaped arrow pointing to the central metal ion represent in a diagram?

A

Represents bonds coming towards you

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63
Q

For coordinate bonds, what does a dashed arrow pointing to the central metal ion represent in a diagram?

A

Represents a bond sticking out behind the molecule

64
Q

What is the shape of a complex ion with 4 coordinate bonds?

A

Tetrahedral shape

65
Q

What is the bond angle of a 3D complex ion structure with 4 coordinate bonds?

A

109.5°

66
Q

What is the bond angle of complex ion structure with 4 coordinate bonds that form a square planar shape?

A

90°

67
Q

Give an example of a tetrahedral complex ion which has bond angles of 90°?

A

Cisplatin

68
Q

Why are the bond angles in cisplatin 90°?

A

Because the 4 coordinate bonds form a square planar shape

69
Q

What is cisplatin?

A

An anti-cancer drug

70
Q

In the complex ion structure [Fe(en)3]3+, what does the ‘en’ stand for?

A

One ethane-1,2-diamine ligand

71
Q

Give an example of a bidentate ligand

A

ethane-1,2-diamine ligand

72
Q

Give an example of an octahedral complex ion

A

[Fe(H2O)6]2+

73
Q

What are stereoisomers?

A

Molecules with the same structural formula but a different orientation of their bonds in space

74
Q

What is an optical isomer?

A

An isomer of a complex ion, where an ion can exist as 2 non-superimposable mirror images

75
Q

What shape of complex ion does optical isomerism occur?

A

In octahedral complexes with 3 bidentate ligands attached to the central ion

76
Q

What are optical isomers known as?

A

Enantiomers

77
Q

Describe what the trans isomer looks like for a square planar complex ions with 2 pairs of ligands?

A

When 2 paired ligands are directly opposite each other

78
Q

Describe what the cis isomer looks like for a square planar complex ions with 2 pairs of ligands?

A

When 2 paired ligands are directly opposite each other

79
Q

What is cisplatin made of?

A

A complex of platinum (II) with 2 chloride ions and 2 ammonia molecules in a square planar shape

80
Q

What is cancer caused by, and why does cisplatin help?

A

Cancer is caused by cells in the body dividing uncontrollably and forming tumours. Cisplatin helps because it prevents cancer cells from reproducing

81
Q

How does cisplatin stop cancer cells from reproducing?

A

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
Q

What does the trans isomer look like for an octahedral complex with 4 ligands of one type and 2 ligands of another type?

A

If the 2 odd ligands are opposite each other

83
Q

What does the cis isomer look like for an octahedral complex with 4 ligands of one type and 2 ligands of another type?

A

If the 2 odd ligands are next to each other

84
Q

What is a downside with using cisplatin to stop cancer?

A

It stops normal cells from replicating, causing hair loss, a weaker immune system and could cause damage to the kidneys

85
Q

What is ligand substitution?

A

When 1 ligand is swapped for another ligand

86
Q

What does ligand substitution normally cause?

A

A colour change

87
Q

What happens when ligand substitution occurs of similarly sized ligands?

A

The coordination number of the complex ion doesn’t change, and neither does the shape

88
Q

What happens if an H2O ligand is swapped for a NH3 ligand?

A

Because they’re similar sizes, the shape and coordination number doesn’t change, but the colour does change

89
Q

What happens when ligand substitution occurs of different sized ligands?

A

A change in coordination number and shape occurs

90
Q

What is partial ligand substitutuion?

A

When not all of the ligands are substituted

91
Q

For predicting the outcome of unusual reactions, what can be said about H2O, NH3, OH-, CN- and Cl- ligands?

A

H2O, NH3, OH-, CN- are all similar size but Cl- ions are a lot larger

92
Q

What is Haemoglobin?

A

A protein found in the blood that helps to transport oxygen around the body

93
Q

What is Haemoglobin made of?

A

Fe2+ ions which are hexa-coordinated to six lone pairs

94
Q

What is the Haem part of Haemoglobin made up of?

A

4 lone pairs that come from nitrogen atoms form a circle around the Fe2+

95
Q

What is porphyrin?

A

A multidentate ligand made up of the molecule that the 4 nitrogen atoms are a part of in haemoglobin

96
Q

What shape structure is formed around the Fe2+ ion in haemoglobin?

A

An octahedral shape

97
Q

What 3 things make up the octahedral shape of haemoglobin?

A

A porphyrin ring
A globin (protein)
Either a water or oxygen molecule

98
Q

What is the haemoglobin complex called when water bonds to an Fe2+ ion?

A

Deoxyhaemoglobin

99
Q

What is the haemoglobin complex called when oxygen bonds to an Fe2+ ion?

A

Oxyhaemoglobin

100
Q

How does haemoglobin transport oxygen around the body?

A

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
Q

Describe the process, involving haemoglobin, which happens in the lungs

A

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
Q

What happens when the oxyhaemoglobin reaches the place where oxygen is needed?

A

The oxygen molecules are exchanged for a water molecule. The haemoglobin then travels back to the lungs where the whole process starts again

103
Q

What happens to the haemoglobin when carbon monoxide is inhaled?

A

The haemoglobin exchanges its oxygen ligand for a carbon monoxide ligand, forming carboxyhaemoglobin.

104
Q

Why is inhaling carbon monoxide bad?

A

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
Q

What does carbon monoxide poisoning do and what are the health affects?

A

It starves the organs of oxygen causing headaches, dizziness, unconsciousness and death if not treated

106
Q

What is the colour of oxyhaemoglobin?

A

Red, which is why red blood cells are red

107
Q

What is the product when you mix an aqueous solution of transition metal ions with aqueous sodium hydroxide or aqueous ammonia?

A

You get a coloured hydroxide precipitate

108
Q

What is the notation for precipitation reactions of aqueous solution of transition metal ions?

A

M^(n+) ( you leave out any water ligands)

109
Q

In water, what does sodium hydroxide dissociate into?

A

Na+ and OH- ions

110
Q

What is a precipitate?

A

A solid formed in a solution

111
Q

What is the equation for the reaction between an iron ion (Fe2+) and aqueous sodium hydroxide? Include the water ligands

A

[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
Q

What is the equation for the reaction between an iron ion (Fe2+) and aqueous ammonia? Include the water ligands

A

[Fe(H2O)6]2+ + 2OH- —> Fe(OH)2(H2O)4 + 2NH4+

113
Q

What is the colour change in the reaction between an aqueous iron ion (Fe2+) and aqueous ammonia or aqueous sodium hydroxide?

A

Pale green —> Darker green precipitate

114
Q

What is the colour change in the reaction between an aqueous copper ions ( Cu(II) ) and aqueous ammonia or aqueous sodium hydroxide?

A

Pale blue —> Blue precipitate

115
Q

What is the colour change in the reaction between an aqueous manganese ions ( Mn(II) ) and aqueous sodium hydroxide or aqueous ammonia?

A

Pale pink —> Pink/Buff (sandy colour) precipitate

116
Q

What is the colour change in the reaction between an aqueous iron ions ( Fe(III) ) and aqueous sodium hydroxide or aqueous ammonia?

A

Yellow —> Orange precipitate

117
Q

What is the colour change in the reaction between an aqueous chromium ions ( Cr(III) ) and aqueous sodium hydroxide or aqueous ammonia?

A

Green —> Grey-green precipitate

118
Q

Write the equation for copper (II) reacting with aqueous sodium hydroxide (include water ligands)

A

[Cu(H2O)6]2+ + 2OH- —> Cu(OH)2(H2O)4 + 2H2O

119
Q

Write the equation for manganese (II) reacting with aqueous sodium hydroxide (include water ligands)

A

[Mn(H2O)6]2+ + 2OH- —> Mn(OH)2(H2O)4 + 2H2O

120
Q

Write the equation for copper (II) reacting with aqueous ammonia (include water ligands)

A

[Cu(H2O)6]2+ + 2NH3 —> Cu(OH)2(H2O)4 + 2NH4+

121
Q

Write the equation for manganese (II) reacting with aqueous ammonia (include water ligands)

A

[Mn(H2O)6]2+ + 2NH3 —> Mn(OH)2(H2O)4 + 2NH4+

122
Q

Write the equation for iron (III) reacting with aqueous sodium hydroxide (include water ligands)

A

[Fe(H2O)6]3+ + 3OH- —> Fe(OH)3(H2O)3 + 3H2O

123
Q

Write the equation for chromium (III) reacting with aqueous sodium hydroxide (include water ligands)

A

[Cr(H2O)6]3+ + 3OH- —> Cr(OH)3(H2O)3 + 3H2O

124
Q

Write the equation for chromium (III) reacting with aqueous ammonia (include water ligands)

A

[Cr(H2O)6]3+ + 3NH3 —> Cr(OH)3(H2O)3 + 3NH4+

125
Q

Write the equation for iron (III) reacting with aqueous ammonia (include water ligands)

A

[Fe(H2O)6]3+ + 3NH3 —> Fe(OH)3(H2O)3 + 3NH4+

126
Q

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+?

A

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
Q

Why do transition metals exist in different oxidation states?

A

Because they can change oxidation state by gaining or losing electrons in redox reactions (also resulting in a colour change)

128
Q

Describe the interconversion between Fe2+ and Fe3+ ions

A

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
Q

Name an oxidising agent used for the interconversion of iron ions

A

Acidified potassium manganate (VII) solution

130
Q

What is the full equation for the oxidation of Fe2+ to Fe3+ by Mn(VII) ions in acid solution?

A

Mn04- + 8H+ + 5Fe2+ —> Mn2+ + 4H2O + 5Fe3+

131
Q

What is the colour change for the oxidation of Fe2+ to Fe3+ by Mn(VII) ions in acid solution?

A

Fe2+ is pale green and Fe3+ is yellow

Pale green —> Yellow

132
Q

Name a reducing agent used for the interconversion of iron ions

A

Iodide solution

133
Q

What is the full equation for the reduction of Fe3+ to Fe2+ by I- ions?

A

2I- + 2Fe3+ —> 2Fe2+ + I2

134
Q

What is the first colour change for the oxidation of Cr3+ to dichromate (VI) Cr2O7 2-?

A

Dark green —> Yellow

135
Q

What is the second colour change for the oxidation of Cr3+ to dichromate (VI) Cr2O7 2-?

A

Yellow —> Orange

136
Q

Why are there 2 colour changes in the oxidation of Cr3+ to dichromate (VI) Cr2O7 2-?

A

Because after the first colour change, sulfuric acid is added to the chromate (VI) solution to produce a dichromate (VI) solution

137
Q

What is the oxidising agent used for the oxidation of Cr3+ to dichromate (VI) Cr2O7 2-?

A

Hydrogen peroxide solution

138
Q

What is the reducing agent used in the reduction of dichromate (VI) Cr2O7 2- to Cr3+?

A

Acidified zinc

139
Q

Describe the copper redox reactions

A

Cu2+ ions can be reduced to Cu+, giving an oxidation number change of +2 to +1

140
Q

Describe the disproportionation reaction of Cu+ ions

A

Cu+ is unstable so spontaneously disproportionates - meaning copper is oxidised and reduced at the same time

141
Q

Write the full equation for the disproportionation reaction of Cu+ ions

A

2Cu+ —> Cu2+ + Cu

142
Q

Describe how you can identify transition metal ions

A

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
Q

For the test to identify transition metal ions, what colour is the precipitate of Cu2+ ions?

A

Blue

144
Q

For the test to identify transition metal ions, what colour is the precipitate of Fe2+ ions?

A

Green

145
Q

For the test to identify transition metal ions, what colour is the precipitate of Fe3+ ions?

A

Orange

146
Q

For the test to identify transition metal ions, what colour is the precipitate of Mn2+ ions?

A

Pink / Buff (sandy colour)

147
Q

For the test to identify transition metal ions, what colour is the precipitate of Cr3+ ions?

A

Grey-green

148
Q

Describe the test for halide ions

A

Add nitric acid, followed by silver nitrate solution. If chloride, bromide or iodide ions are present then a precipitate will form

149
Q

In the test for halide ions, what colour is the precipitate of AgBr (silver bromide)?

A

Cream

150
Q

In the test for halide ions, what colour is the precipitate of AgCl (silver chloride)?

A

White

151
Q

In the test for halide ions, what colour is the precipitate of AgI (silver iodide)?

A

Yellow

152
Q

Describe the test for sulfates

A

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
Q

Why do you add the dilute strong acid in the test for sulfates?

A

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
Q

Describe the test for carbonates

A

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
Q

Describe the test for ammonium ions

A

Use a damp piece of red litmus paper. If there are ammonium ions present, the litmus paper will turn blue

A Level Chemistry Year 2 (7 decks)

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