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Transition Metals Flashcards

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1
Q

What is a transition metal?

A

A metal that can form one or more stable ions with an incomplete sub shell

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2
Q

What should you remember when working out electron configuration?

A

4s fills and empties before 3D

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3
Q

What are the electron configurations of Cr and Cu?

A

[Ar]4s1 3d5

[Ar]4s1 3d10

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4
Q

What is the electron configuration of iron and it’s 2 common ions?

A

Fe [Ar]3d6 4s2
Fe 2+ [Ar] 3d6
Fe 3+ [Ar]3d5

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5
Q

What is the electron configuration of Sc and Sc3+?

A

[Ar] 4s2 3d1

[Ar]

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6
Q

What is are the electron configurations of Zn and Zn2+?

A

[Ar] 4s2 3d10

[Ar] 3d10

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7
Q

Why are Sc and Zn not transition metals?

A

Neither have an incomplete d sub shell in any of their ions

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8
Q

What is a ligand?

A

A particle with a lone pair which bonds to a metal by a coordinate bond

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9
Q

What is a complex?

A

A metal central ion which has got coordinately bonded ligands

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10
Q

What is the coordination number?

A

The number of coordinate bonds to the metal ion

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11
Q

What is a Lewis base?

A

A lone pair donor

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12
Q

What is a Lewis acid?

A

A lone pair acceptor

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13
Q

How do you describe a complex?

A 
Write the metal 
Then the ligand molecules 
Then the number of ligands 
Then add a square brackets round 
Then add the charge 
[Cu(H2O)]2+
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14
Q

Describe a linear complex

A

Coordination number: 2
Shape: 2*180 degree angles
Occurrence: Ag+ complexes
Example: Tollens reagent - [Ag(NH3)2]+

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15
Q

Describe a square planar complex

A

Coordination number: 4
Shape: flat with 4*90 angles
Occurrence: Pt2+, Ni2+
Example: [Pt(Cl4)]2-

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16
Q

Describe a tetrahedral complex:

A

Coordination number: 4
Shape: triangle pyramid with bond angle of 109.5 degrees.
Occurrence: Cl- or larger charged ions
Example: [Cu(Cl4)]2-

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17
Q

Describe an octahedral complex

A 
The most common
Coordination number: 6 
Shape: 90 degree angles 
Occurrence: most complexes with small ligands (H2O, NH3, OH-)
Example: [Cu(H2O)6]2+
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18
Q

Why is a ligand monodentate?

A

Ions only form one ligand

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19
Q

What is an example of a monodentate ligand?

A

OH-
H2O
NH3
Cl-

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20
Q

What is a bidentate ligand?

A

An ligand that can form 2 coordinate bonds to a transition metal

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21
Q

How many coordinates can EDTA form?

A

6

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22
Q

What is it called when an ion can form more than two ligands to a transition metal?

A

Multidentate

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23
Q

How do you work out the oxidation state of a metal ion?

A 
Total charge of the complex-the sum of the charges of the ligands
Eg [Cu(H2O)]2+ 
\+2-0=+2
EG [Cu(H2O)4(OH-)2]
0- -2= +2
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24
Q

In which complexes can you observe stereoisomerism?

A

Square planar

Octahedral

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25
Q

Two complexes have the same formula but different orientations in space, what are they?

A

Optical isomers so they are enantiomers of each other

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26
Q

What is optical isomerism?

A

Two non-superimposable mirror images

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27
Q

Why does a transition metal complex change colour?

A

Change in oxidation state
Change in ligand
Change in the coordination number

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28
Q

Why are transition metal complex ions coloured?

A

-Only transition metal complexes ions have colours.
-the d orbitals split into 2 sets as the electrons from the
ligands interfere with it.
- this creates a set of 3 orbitals and a set of 2 orbitals
-These sets are at different energy levels - the 3-orbital set is at a lower energy level than the 2-orbital set.
-Hence, a specific amount of energy is needed for an electron to move from the lower orbitals to the higher orbitals.
-When light is shone onto the complex ion, certain frequencies of light are absorbed the which promotes an electron to a ‘higher’ orbital
-Any light which is not absorbed is the colour of the complex ion as the non-absorbed light is reflected back into our eyes

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29
Q

What equation can be used to work out the energy difference between the ground state and the
excited state of the d electrons?

A 
∆E = hν = hc/λ
h- planks constant 
v(miu)- frequency of light absorbed 
λ- wavelength 
c- is speed of light
30
Q

what is a d to d transition?

A

when an electron in the 3 orbital set of electrons is promoted to the 2 orbital set when its excited by light

31
Q

How can you use colorimetry to identify the concentration of a transition metal ion complex?

A
  • zero the calorimeter
  • take know conc of solution
  • measure the absorbance of known solution
  • plot a calibration curve
  • all light should be passed through a filter
  • Which is passed through the sample
  • plot relative absorbance against concentration of know solution
  • identify sample absorbance to extract concentration
32
Q

What is the colour and oxidation state of VO2^+?

A

Yellow +5

33
Q

What is the colour and oxidation state of VO^+2?

A

Blue +4

34
Q

What is the oxidation state and colour of V^3+?

A

Green +3

35
Q

What is the colour and oxidation state of V^2+?

A

Violet 2+

36
Q

How do you react vanadium with zinc?

A

Produce a half equation for each then add them

Zinc reduces vanadium to a lower oxidation state

37
Q

Acidic conditions favour which reaction?

A

Reduction

38
Q

Alkaline conditions favour which reaction?

A

Oxidation

39
Q

Why does tollens reagent turn silver?

A

It gets oxidised by the aldehyde and it’s a transition metal ion complex

40
Q

What is the equation for the oxidation of tollens reagent?

A

RCHO+2[Ag(NH3)2]+3OH- to RCOOH+ 2Ag+ 4NH3+2H2O

41
Q

When is a metal aqua ion soluble?

A

When it has a charge

No charge - not soluble

42
Q

A neutral metal aqua ion forms what?

A

An insoluble precipitate

43
Q

How can you tell if a reaction is acid base reaction or a ligand substitution?

A

If the molecule you react with the ligand becomes part of it it’s a ligand substitution, if it doesn’t it’s an acid base reaction

44
Q

What is an acid base reaction?

A

Accepts or donated protons

45
Q

Required practical: how do you identify unknown metal ion?

A

To each test tube add sample of unknown solution
To the first test tube add dropwise NaOH
The second dropwise NH3
The third dropwise NaCO3
Record observations for each

46
Q

What colours are iron 2 copper 2 iron 3 aluminium 3 as aqueous ions?

A

Iron 2-green solution
Copper 2- blue solution
Iron 3- purple solution (can look yellow brown)
Aluminium 3- colourless solution

47
Q

What is formed and what colour when iron 2 copper 2 iron 3 aluminium 3 as aqueous ions turn when NaOH is added?

A

Each remain the same colour as their iron and form instead a precipitate
Except iron 3 which forms a brown precipitate
Iron 2 precipitate goes brown standing in air
The Aluminium precipitate is white
The iron 2 precipitate is green

48
Q

What happens when iron 2 copper 2 iron 3 aluminium 3 an excess of NaOH is added to the NaOH precipitates?

A

They all remain the same except aluminium 3 which returns to a colourless solution as when it was an ion

49
Q

What happens when dilute NH3 is added to the iron 2 copper 2 iron 3 aluminium 3 precipitates of NaOH?

A

Iron 2-green precipitate remains, but goes brown standing in air
Copper 2- remains blue precipitate
Iron 3- remains brown precipitate
Aluminium 3- reforms white precipitate

50
Q

What happens when excess dilute NH3 is added in excess to the iron 2 copper 2 iron 3 aluminium 3 precipitates of NaOH?

A

No further change

Except copper 2 turns deeper blue

51
Q

What happens when Na2CO3 is added to iron 2 copper 2 iron 3 aluminium 3 solutions and precipitates of excess NH3 ?

A

Iron 2- remains green precipitate, but doesn’t go brown in air
Copper 2- turns to blue green precipitate
Iron 3- remains brown precipitate, but CO2 gas is evolved
Aluminium 3- remains white precipitate but CO2 gas is evolved

52
Q

Why might the iron 3 aqueous ion look yellow brown instead of purple?

A

Some [Fe(H20)5(OH)]2+ may be present

53
Q

What is the formula of the aqueous iron 2 ion?

A

[Fe(H2O)6]2+ (aq)

54
Q

What is the formula of the copper 2 aqueous ion?

A

[Cu(H2O)6]2+

55
Q

What is the formula of the iron 3 aqueous ion?

A

[Fe(H2O)6]3+

56
Q

What is the formula of the aluminium 3 aqueous ion?

A

[Al(H2O)6]3+

57
Q

Give the formulae for the reactions of iron 2 and 3 with OH- ions:

A

[Fe(H2O)6]2+(aq) + 2OH–(aq) ==> Fe(H2O)4(OH)2 + 2H2O(l)

[Fe(H2O)6]3+(aq) + 3OH–(aq) ==> Fe(H2O)3(OH)3 + 3H2O(l)

58
Q

Give the formulae for the reactions of copper 2 and aluminium 3 with OH- ions:

A

[Cu(H20)6]2+(aq) + 2OH–(aq) ==> Cu(OH)2(H2O)4 + 2H20

[Al(H2O)6]3+(aq) + 3OH–(aq) ==> Al(OH)3(H2O)3 + 3H2O(l)

59
Q

what is the equation for aluminium in excess NaOH?

A

Al(OH)3(H20)3 + 3OH-(aq) to [Al(OH)6]3-(aq) + 3H2O(l)

White precipitate to colourless solution

60
Q

Why does aluminium react in NaOH and excess NaOH?

A

it’s amphoteric it also reacts with acids

[Al(OH)3(H2O)3}(s) + 3H+ to [Al(H2O)6]3+ (aq)

61
Q

Give the formulae for the reactions of iron 2 and 3 with NH3:

A

[Fe(H2O)6]2+(aq) + 2NH3(aq) to [Fe(H2O)4(OH)2] (s)+ 2NH4+(aq)

[Fe(H2O)6]3+(aq) + 3NH3(aq) to Fe(H2O)3(OH)3 + 3NH4+(aq)

62
Q

Give the formulae for the reactions of copper 2 and aluminium 3 with NH3:

A

[Cu(H20)6]2+(aq) +2NH3(aq) to Cu(H20)4(OH)2 + 2NH4+(aq)

[Al(H2O)6]3+(aq) + 3NH3(aq) to Al(H2O)3(OH)3 + 3NH4+(aq)

63
Q

Give the formula for the reaction of copper 2 and NH3 in excess:

A

Cu(H2O)4(OH)2 + 4NH3(aq) to [Cu(NH3)4(H2O)2]2+(aq) + 2OH–(aq) + 2H2O(l)

64
Q

Give the formulae for the reactions of iron 2 and 3 with Na2CO3:

A

[Fe(H2O)6]2+(aq) + CO3 2- (aq) to FeCO3(s) + 6H2O(l)

2[Fe(H2O)6]3+(aq) + 3CO3 2- (aq) to 2Fe(H2O)3(OH)3 + 3CO2(g) + 3H2O(l)

65
Q

Give the formulae for the reactions of copper 2 and aluminium 3 with Na2CO3:

A

[Cu(H2O)6]2+ (aq) + CO3 2- (aq) to CuCO3(s) + 6H2O(l)

2[Al(H2O)6]3+(aq) + 3CO3 2- (aq) to 2Al(H2O)3(OH)3 + 3CO2(g) + 3H2O(l)

66
Q

How do we know 3+ ions are more acidic?

A

they react with CO3 2- ions in an acid-base reaction whereas the 2+ ions go through ligand substitution reactions

67
Q

Why are 3+ ions more acidic?

A 
they have a greater charge desity 
so a stronger inductive effect 
which draws electrons in to the metal 
weakening the O-H bond 
Allowing H+ to be released more freely 
therefore its a strionger acid
68
Q

Give the equation for the ligand substitution of conc HCl with hexaaqua cooper :

A

[Cu(H20)6]2+ +4Cl- to 6H20 + [CuCl4]2-

69
Q

Give the ligand substitution of haemoglobin:
And haemoglobin structure
Why is CO dangerous?

A

Made up of a porphyrin ring surrounding a central Fe2+ ion with a H20 ligand 4 N lingands and one N attached to a glob in molecule

Water exchanges with oxygen
Oxygen used up and so becomes water again
Carbon monoxide is dangerous bc it binds irreversibly to haemoglobin as it has a stronger dative covalent bond
So it the iron molecule have been poisoned

70
Q

What is disproportionation?

A

when a species is simultaneously oxidised and reduced

to form more stable forms

71
Q

Why is aqueous copper chemistry limited?

A

It is disproportionated

Chemistry (21 decks)

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