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Chemistry > Chapter 24 - Transition metals > Flashcards

Chapter 24 - Transition metals Flashcards

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1
Q

Where are the d-block elements located ?

A
  • Between group 2 and group 13 on the periodic table
  • From scandium to zinc
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2
Q

Why are they called the d-block elements ?

A
  • The highest energy subshell is 3d
  • Highest energy electrons are in the 3d orbitals
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3
Q

What are the general properties of d-block elements ?

A
  • Metallic
  • Strong
  • High MP + BP
  • Conduct electricity and heat
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4
Q

How should you write the electron configuration for d-block elements ?

A

3d and then 4s

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5
Q

Which two d-block elements have anomalous electron configurations ?

A
  • Chromium
  • Copper
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6
Q

Why do chromium and copper only have 1 electron in the 4s orbital ?

A
  • This is because of stability
  • It is believed that a 3d5 and 3d10 subshell gives additional stability to atoms of chromium and copper
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7
Q

When forming positive ions from their atoms, what do they lose first ?

A

They lose the 4s electrons first and then the 3d electrons

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8
Q

Define transition metals

A

D-block elements that form at leat one ion with a partially filled d orbital

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9
Q

What two elements in the d-block are not transition metals ?

A
  • Zinc
  • Scandium
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10
Q

Why are scandium and zinc not d block elements ?

A

Their ions have full d orbitals

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11
Q

What are the properties of transition metals ?

A
  • Form compounds in which the transition element has different oxidation states
  • They form coloured compounds
  • The elements and their compounds can act as catalysts
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12
Q

What does it mean when it is said that transition metals have variable oxidation states ?

A

They can form compounds with more than one oxidation state

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13
Q

What is the pattern of oxidation states like for transition metals ?

A

The number of oxidations states increases until manganese and then decreases

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14
Q

What oxidation state do all transition metals have ?

A

They all form compounds with an oxidation number of +2

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15
Q

What is the colour of titanium (+3) ?

A

Purple

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16
Q

What is the colour of vanadium(+2) ?

A

Purple

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17
Q

What is the colour of vanadium (+3) ?

A

Green

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18
Q

What is the colour of vanadium (+4) ?

A

Blue

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19
Q

What is the colour of vanadium (+5) ?

A

Yellow

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20
Q

What is the colour of chromium (+2) ?

A

Blue

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21
Q

What is the colour of chromium (3) ?

A

Green

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22
Q

What is the colour of chromium (+6) ?

A

Orange

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23
Q

What is the colour of manganese (+2) ?

A

Pale pink

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24
Q

What is the colour of manganese (+4) ?

A

Dark pink

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25
Q

What is the colour of manganese (+6) ?

A

Green

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26
Q

What is the colour of manganese (+7) ?

A

Purple

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27
Q

What is the colour of iron (+2) ?

A

Light green

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28
Q

What is the colour of iron (+3) ?

A

Yellow

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29
Q

What is the colour of copper (+2) ?

A

Pink

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30
Q

What is the colour of copper (+3) ?

A

Green

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31
Q

What colour is Nickel (+2) ?

A

Green

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32
Q

What colour is Copper (+2) ?

A

Blue

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33
Q

What are the 4 reactions in which transition metals act as catalysts ?

A
  • Haber process - Iron catalyst
  • Contact process - Vanadium oxide catalyst
  • Manufacture of margarine - Nickel catalyst
  • Decomposition of H2O2 - Manganese oxide catalyst
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34
Q

Give 2 example of homogenous catalysts (transition metal)

A
  • Reaction between iodide ions and peroxodisulfate ions - Iron ions catalyst
  • Zinc metal reacting with acids - Copper ions catalyst
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35
Q

What is a complex ion ?

A

A complex ion is formed when one or more molecule/negatively charged ions bond to a central metal ion

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36
Q

What is a ligand ?

A

A ligand is defined as a molecule or ion that donates a pair of electrons to a central metal ion to form a coordinate bond

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37
Q

What is a coordinate bond ?

A

A covalent bond that is formed when one of the bonded atoms provides both of the electrons for the shared pair

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38
Q

What is the coordination number ?

A

It indicates the number of coordinate bonds attached to the central metal ion

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39
Q

It indicates the number of coordinate bonds attached to the central metal ion

A

A ligand that is able to donate one pair of electrons to a central metal ion

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40
Q

What are the neutral monodentate ligands ?

A
  • H2O
  • NH3
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41
Q

What are the charged monodentate ligands ?

A
  • Halide ions
  • CN-
  • OH-
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42
Q

What are bidentate ligands ?

A

Ligands that can donate two lone pairs of electrons to the central metal ion

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43
Q

What are the two common bidentate ligands ?

A
  • 1,2 - diaminoethane
  • ethanedioate ion
44
Q

What are the most common coordination numbers ?

A

4 and 6

45
Q

What shape does a coordination number of 6 give ?

A

Octahedral

46
Q

What shapes do a coordination number of 4 give ?

A
  • Tetrahedral
  • Square planar
47
Q

When does a square planar shape occur in complex ions ?

A

Occurs in complex ions of transition metals with 8 electrons in the highest energy d sub shell

48
Q

Which three metals can form a square planar complex ion ?

A
  • Platinum(II)
  • Palladium(II)
  • Gold(III)
49
Q

What is stereoisomerism ?

A

Same structural formula but a different arrangement of the atoms in space

50
Q

What types of stereoisomerism can complex ions display ?

A
  • Cis/trans
  • Optical
51
Q

For complex ions, what does the type of stereoisomerism depend on ?

A
  • The number and type of ligands that are attached to the central metal ion
  • The shape of the complex
52
Q

What complex ions show only cis-trans isomerism ?

A

Some 4 coordinate and 6 coordinate complex ions that contain two different monodentate ligands

53
Q

What complex ions show optical and cis-trans isomerism ?

A

Some 6 coordinate complex ions containing monodentate and bidentate ligands

54
Q

Are double bonds needed for cis trans isomerism in complex ions ?

A

No

55
Q

What dictates the cis trans isomerism in complex ions ?

A

The central metal atom

56
Q

For square planar, what is the cis isomer ?

A
  • Two identical groups are adjacent to each other
  • Coordinate bonds between the identical ligands are 90 degrees apart
57
Q

For square planar, what is the trans isomer ?

A
  • Two identical groups are opposite each other
  • Coordinate bonds between the identical ligands are 180 degrees apart
58
Q

For octahedral, what is the cis isomer ?

A
  • Two identical groups are adjacent to each other
  • Coordinate bonds between the identical ligands are 90 degrees apart
59
Q

For octahedral, what is the trans isomer ?

A
  • Two identical groups are opposite each other
  • Coordinate bonds between the identical ligands are 180 degrees apart
60
Q

For optical isomerism in octahedral complexes, what does their need to be ?

A

They have to have two or more bidentate ligands

61
Q

What are optical isomers ?

A
  • Enantiomers
  • Non superimposable mirror images of each other
62
Q

Can trans isomers form optical isomers ?

A

No

63
Q

Why cant trans isomers form optical isomers ?

A

A mirror image is exactly the same and can be superimposed

64
Q

What is a ligand ?

A

A molecule or ion that donates a pair of electrons to a central metal ion to form a coordinate or dative bond

65
Q

What is a ligand substitution reaction ?

A

One in which one ligand in a complex ion is replaced by another ligand

66
Q

What is formed when copper (II) sulphate is dissolved in water ?

A

[Cu(H2O)6]2+ is formed in aqueous solution

67
Q

What colour is the [Cu(H2O)6]2+ ion ?

A

Pale blue complex ion

68
Q

What happens when excess ammonia is added to a solution containing [Cu(H2O)6]2+ ?

A

The pale blue solution changes to form a dark blue solution

69
Q

What is the equation for [Cu(H2O)6]2+ reacting with excess ammonia ?

A
  • [Cu(H2O)6]2+ + 4NH3 → [Cu(NH3)4(H2O)2]2+ + 4H2O
  • Pale blue solution to a dark blue solution
  • However both are octahedral complex ions
70
Q

How should you add the ammonia to the solution ?

A
  • Dropwise
  • So you can see all the observations
71
Q

What do you see when you add ammonia drop wise to [Cu(H2O)6]2+ ?

A
  • A pale blue precipitate of Cu(OH)2 is formed in the first stage of the reaction.
  • The Cu(OH)2 precipitate then dissolves in excess ammonia to form a dark blue solution
72
Q

What can be used as a source of chloride ions ?

A

HCl

73
Q

What happens to [Cu(H2O)6]2+ when an excess of HCl is added ?

A
  • The pale blue solution changes colour to form a yellow solution
  • 6 ligands replaced with 4 ligands
74
Q

What happens if water is added to the yellow [CuCl4]2- solution ?

A
  • A blue solution will be formed
  • It will be more dilute and paler than the original blue solution
75
Q

What is the equation for [Cu(H2O)6]2+ reacting with excess chloride ?

A
  • [Cu(H2O)6]2+ + 4Cl- → [CuCl4]2- + 6H2O
  • Pale blue solution to yellow solution
  • Octahedral to tetrahedral
76
Q

When chlorine is added to [Cu(H2O)6]2+, why does it turn into tetrahedral ?

A
  • This is because the chlorine ligands are larger in size than the water ligands, so fewer chloride ligands can fit around the central metal ion
  • This explains the change in coordination number
77
Q

What is formed when chromium (III) potassium sulphate is dissolved in water ?

A

[Cr(H2O)6]3+ ion is formed

78
Q

What colour is the [Cr(H2O)6]3+ ion ?

A

Pale purple solution

79
Q

What happens when chromium sulphate is dissolved in water ?

A

[Cr(H2O)5SO4]+ ion is formed

80
Q

What colour is the [Cr(H2O)5SO4]+ ion ?

A

It is a green solution

81
Q

What happens when [Cr(H2O)6]3+ reacts with an excess of ammonia ?

A

The [Cr(NH3)6]3+ ion is formed

82
Q

What happens when [Cr(H2O)6]3+ reacts with an excess of ammonia (dropwise) ?

A
  • Initially a grey-green precipitate of Cr(OH)3 is formed.
  • The Cr(OH)3 precipitate dissolves in excess ammonia to form the complex ion [Cr(NH3)6]3+
83
Q

What is the equation for the ligand substitution between [Cr(H2O)6]3+ and ammonia ?

A
  • [Cr(H2O)6]3+ 6NH3 → [Cr(NH3)6]3+ + 6H2O
  • Violet to purple colour change
84
Q

What is a precipitation reaction ?

A

A precipitation reaction occurs when two aqueous solutions containing ions react together to form an insoluble ionic solid, called a precipitate.

85
Q

How do copper, iron and manganese ions react with NaOH ?

A

They form precipitates

86
Q

What does Cu2+ look like in aqueous solution ?

A

Blue solution

87
Q

What does Fe2+ look like in aqueous solution ?

A

Pale green solution

88
Q

What does Fe3+ look like in aqueous solution ?

A

Pale yellow solution

89
Q

What does Mn2+ look like in aqueous solution ?

A

Pale pink solution

90
Q

What does Cr3+ look like in aqueous solution ?

A

Violet solution

91
Q

What happens when Cu2+ reacts drop wise with NH3 or NaOH ?

A

Blue precipitate is formed

92
Q

What happens when Fe2+ reacts drop wise with NH3 or NaOH ?

A
  • Green precipitate is formed
  • Turns orange brown on standing
93
Q

What happens when Fe3+ reacts drop wise with NH3 or NaOH ?

A

Orange brown precipitate

94
Q

What happens when Mn2+ reacts drop wise with NH3 or NaOH ?

A

Light brown precipitate

95
Q

What happens when Cr3+ reacts drop wise with NH3 or NaOH ?

A

Grey green precipitate

96
Q

What happens when Cu2+ reacts with excess NH3 ?

A

Dissolves to form dark blue solution

97
Q

What happens when Fe2+ reacts with excess NH3 ?

A
  • Green precipitate is formed
  • insoluble
98
Q

What happens when Fe3+ reacts with excess NH3 ?

A
  • Orange brown precipitate
  • insoluble
99
Q

What happens when Mn2+ reacts with excess NH3 ?

A
  • Light brown precipitate
  • insoluble
100
Q

What happens when Cr3+ reacts with excess NH3 ?

A

Dissolves to form purple solution

101
Q

What happens when Cu2+ reacts with excess NaOH ?

A
  • Insoluble
  • Cu(OH)2
102
Q

What happens when Fe2+ reacts with excess NaOH ?

A
  • Green precipitate is formed
  • Insoluble
  • Turns brown on standing
  • Fe(OH)2
103
Q

What happens when Fe3+ reacts with excess NaOH ?

A
  • Orange brown precipitate
  • Insoluble
  • Fe(OH)3
104
Q

What happens when Mn2+ reacts with excess NaOH ?

A
  • Light brown precipitate
  • Insoluble
  • Mn(OH)2
105
Q

What happens when Cr3+ reacts with excess NaOH ?

A

Dissolves to form dark green solution

Chemistry (29 decks)

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