Transition Metals Flashcards

1
Q

Where do the properties of transition metals come from

A

A partially filled D sub level in their atoms or ions

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2
Q

What are 4 characteristics of transition metals

A

Ability to form complexes

Form coloured ions

Variable oxidation states

Good catalysts

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3
Q

Why is zinc not a transition metal

A

It can only form a 2+ ions which gives it a completely filled d orbital so it doesn’t meet the criteria of being a transition metal

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4
Q

What is a complex

A

Transition metals or their ions forming Co ordinate bond with ligands

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5
Q

What is a ligand

A

A species that can donate one or more lone pair of electrons to a transition metal atom/ion

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6
Q

What is the co ordination number

A

The number of co ordinate bonds formed to a central metal ion

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7
Q

Shape and angle for 6 co ordinate bonds

A

Octahedral

90 degrees

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8
Q

Shape and angle for 4 co ordinate bonds (2)

A

Tetrahedral - 109.5

Square planar - 90

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9
Q

Shape and angle for 2 co ordinate bonds

A

Linear - 180

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10
Q

What is a monodentate ligand

A

Ligands that form one co ordinate bond with the metal ion

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11
Q

What are 4 monodentate ligands

A

H2O

Cl -

NH3

CN-

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12
Q

What is a bidentate ligand

A

Ligands that can form 2 co ordinate bonds with a metal ion as they have 2 atoms with lone pairs

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13
Q

What are 2 bidentate ligands
(Draw them out)

A

Ethane-1,2-diamine (en)

Ethanedioate ion

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14
Q

What are multidentate ligands

A

Ligands that can form 3 or more co ordinate bond with a metal ion

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15
Q

What is an example of a multidentate ligand and how many co ordinate bonds does it form

A

EDTA

Forms 6 co ordinate bonds

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16
Q

What 2 atoms have the lone pairs in EDTA

A

Oxygen and nitrogen

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17
Q

What is the structure of platin and cis platin

A

Draw

Square planar
Pt in middle
2 ammonia
2 cl
Swap based on isomerism

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18
Q

What types of isomerism can complexes form

A

Optical

Cis - trans

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19
Q

What is cis trans isomerism

A

A type of EZ isomerism

Cis = same side
Trans = opposite sides

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20
Q

When can optical isomerism in complexes

A

Octahedral complexes where there are 3 bidentate ligands to the central atom

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21
Q

What are the conditions for cis trans isomerism in square planar and octahedral complexes

A

2 of one ligand and 2 of another

4 of one ligand and 2 of another

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22
Q

What are 3 things that cause colour changes

A

Changes in

Oxidation state
Co ordination number
Ligand

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23
Q

Why do transition metals form coloured ions

A

They absorb energy corresponding to certain parts of the visible electromagnetic spectrum - the colour that is seen is made of the parts of the visible spectrum that aren’t absorbed

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24
Q

How does the colour change occur in terms of orbitals

A

In the presence of a ligand the d sub level can split orbitals - some into higher energies and some in lower

This changes energy and therefore the frequency of light absorbed

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25
Q

What is the link between change in E and the absorbing of colours

A

It it is small then it only absorbs the lower end of ROYGBIV

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26
Q

What are the 2 equations for change in E

A

Delta E = hf

Delta E = hc / wavelength

H is planks constant (6.63 x 10^-34)
F is frequency in Hz or s^-1
C is speed of light ( 3x10^18) m/s

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27
Q

What is the equation for C (speed of light)

A

Frequency x wavelength

Therefore delta E can also be hc / lander

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28
Q

What factors affect Delta E (4)

A

Type of ligand
Shape of complex
Co ordination number
Oxidation state of the metal

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29
Q

What is colourimetry

A

A type of spectroscopy

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30
Q

What light does colourimetry use

A

It uses ultraviolet to visible light

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31
Q

What is colourimetry used for

A

It is used to determine the concentration of transition metal ion complex solutions

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32
Q

How do you make a calibration graph (3)and how do you use it

A

Vary convention of sample

Measure absorbance at each concentration

Draw a graph of conc (x axis) against absorbance (y axis)

Measure absorbance of a sample and then use the graph to determine its concentration

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33
Q

What type of reaction is a ligand substitution reaction

What can it come with

A

When the metal ligand bond is broke. And replaced with a different ligand

Change in colour

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34
Q

Why does the co ordination number also change with chlorine ligand substitution reactions

A

Because chlorine is a bigger molecule that the other monodentate ligands

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35
Q

What is the reaction of aqueous copper chloride with HCl and what is the colour change

A

Cu(H20)6 2+ + 4HCl forms Cu(Cl)4 2- + 6H20

Blue to yellow/green

36
Q

How is oxygen transported in the body

A

Blood has a multidentate ligand in complex called haem
one axial position bonds to globin (haemoglobin)
Othe axial position bonds to oxygen to form oxyhaemoglobin
When oxygen transported to tissues to bond breaks and is replaced by water in a partial Ligand sub reaction

37
Q

Why is CO dangerous if inhaled

A

It bonds to the Fe 2+ on the axial
The bond is very strong so it can’t be broken therefore prevents oxygen from binding
High conc of co can be life threatening

38
Q

What is entropy (delta S)

A

A measure of disorder in a system

39
Q

What is an increase in entropy

A

A positive entropy change

40
Q

What is delta G
What does it have to be for a spontaneous reaction to occur

A

Gibbs free energy
Negative

41
Q

What is the equation for delay G

A

Delta G = DeltaH - T x DeltaS

42
Q

Why ate monodentate ligand’s substituted by multidenatte

Why is it difficult to reverse the reaction

A

They form more stable complexes
There is an increase in entropy but delta h stays the same so g is negative

Requires a lot of energy cos backwards reaction would require DELTG to be positive but for a spontaneous reaction it has to be negative

43
Q

Why is enthalpy of ligand substitution reactions 0 or almost 0

A

Breaking and forming the same type of bonds usually

44
Q

What 4 oxidation states can Vanadium have

A

+5
+4
+3
+2
+1

45
Q

What is the ion and colour of +5 vanadium

A

VO_2 +

Yellow

46
Q

What is the ion and colour of + 4 Vanadium

A

VO^2+
Blue

47
Q

What is the ion and colour of +3 vanadium

A

V3+
Green

48
Q

What is the ion and colour of +2 vanadium

A

V^2+

Purple

49
Q

What can vanadium be reduced by

A

Adding zinc

50
Q

What characteristic of transition metals makes them good catalyst

A

Variable oxidation states

51
Q

What is the overall equation for the contact process
What is the catalyst
What type or catalyst is it

A

SO2 + 0.5O2 (g) (RVs)-> SO3 (g)

V2O5
Heterogenous

52
Q

What are the 2 equations showing how the catalyst in the contact process is used and reformed

A

SO2 + V2O5 -> SO3 + V2O4

V2O4 + 0.5O2 -> V2O5

53
Q

What is a heterogenous catalyst

A

Catalysts that are in a different state to the reactants - usually catalyst is solid and reactants are gas or in solution

54
Q

Why is a support used in heterogenous catalysis

A

The reaction takes places on the surface of the catalyst so a support increases the surface area which reduces costs

55
Q

What are 3 stages of heterogenous catalysis

A

Reactants adsorb and form weak interactions with the surface

They weaken the bond between reactants so they become easier to break

Products desorb from the surface

56
Q

What is homogenous catalysis

A

Catalysts in the same phase as the reactants usually in aqueous phase

57
Q

How to homogeneous catalysts work

A

They reaction proceeds by an intermediate species in which the transition metal temporarily changes oxidation state

58
Q

What happens when a catalyst is poisoned

Give 2 examples

A

When it is positioned by impurities which reduce the efficiency

For example sulfur in Haber process
Lead in catalytic converters

59
Q

Why can’t leaded petrol be used in cars with catalytic converters

A

The lead strongly adsorbs to the surface of the catalysts

60
Q

Steps of Fe2+ catalyst
For S2O8- and I- reaction

Why is reaction slow uncatalysted

A

Picture

Reacting 2 negative ions - they repel

61
Q

Draw a diagram of enthalpy cos reaction progress

A

Photo

62
Q

What is autocatalysis

A

When one of the products of the reactions acts as a catalyst in the reaction

63
Q

Draw a diagram of mno4- vs time showing autocatalysis in its reaction with C2O4-

Explain it

A

Picture

Reaction speeds up once mn2+ is formed
Then evens out as reactants used up

64
Q

Give the equations for mno4- reacting with c2o4-

A

Picture

65
Q

What type of reaction is the reaction between sodium hydorxide and the metal ions

A

Hydrolysis reaction

66
Q

What is the reaction of 2+ aqua ions with NaoH

A

Aquaion + 2OH- forms aqua ion (4) (oh)2 + 2H20

67
Q

What is the colour change for age2+ aqua ion when it reacts with NaOH

A

Pale green solution
Green precipitate

Fe(h20)4(oh)2

68
Q

Colour change for Cu2+ aqua ion reacting with NaOH

A

Blue solution - blue precipitate
Cu(H20)4(OH)2

69
Q

What do +3 ions form when reaction with NaOH

A

Metal with 3 water molecules, 3 OH

And 3 H20

70
Q

What does aluminium aqua ion form with NaOH

What about in excess

A

Colourless to white ppt

Ppt dissolves to form colourless solution
Al(oh)6 - + 3H2O

71
Q

What is formed when 2+ metals reacts with ammonia

A

Metal with 4 ammonia and 2NH4+

72
Q

What is the colour change for the reactions of 2+ aqua ions with ammonia

A

Same as with NaOH
Same products formed

73
Q

Which is the only one that reacts with excess ammonia

What type do reaction is it

What is the colour change

What is the shape

A

Hexa aqua copper

A ligand substitution reaction

Cu(h20)4(oh)2 + 4Nh3 -> Cu(nh3)4(H2O)2 2+ + 2H20 + 2OH-

Blue precipitate to deep blue solution

Elongated octahedral because Cu-O bonds longer than C-N bonds

74
Q

What is formed when 3+ ions react with ammonia

A

They react with 3 ammonia instead of 2

They form metal (h20)3(oh)3 and 3nh4+

75
Q

What is the colour ur change for aqua fe3+ reacting with ammonia

A

Yellow/brown solution to brown ppt
Colourless solution to white ppt

76
Q

Colour change when fe3+ reacts with naoh

A

Yellow/ brown solution to brown ppt

77
Q

What is the reaction of 3+ aqua ions with carbonate

A

2 of the ions reacts with 3 carbonates.
To form 2 of metal(h20)3(oh)3 and 3H20 and 3CO2

78
Q

What is the colour change and observation when fe3+ reacts with carbonate

A

Yellow brown solution to brown ppt and fizzing

79
Q

Colour change and observation when Al3+ aqua ion reacts with carbonates

A

Colourless solution to white ppt
Fizzing

80
Q

What is the reaction when carbonates react with 2+ aqua ions

A

One aqua ion with one carbonate ion forms Metal CO3 and 6H20

81
Q

Reaction of Fe2+ aqua ion with carbonate

A

Pale green solution to green ppt

82
Q

Reaction to Cu2+ aqua ion with carbonate

A

Blue solution to blue/green ppt

83
Q

Why do only the +3 complexes cause fizzing with carbonates

A

The O-H bond is weak enough for carbonate ions to remove the H+ from the water ligands

84
Q

Why is the O-H bond weaker in 3+ ions

A

They have a higher charge density so they attracts a pair of electron int he metal - oxygen bond towards itself more strongly which weakens the O-H bond

85
Q

What is an example of a linear complex

A

Ag(NH3)2 2+

Cu(NH3)2 2+