Transition Metals Part 1 Flashcards

1
Q

Transition metal

A

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

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2
Q

Why are Sc and Zn d block elements

A

Because their outer electron is in a (3)d sub shell

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3
Q

Why are Sc and Zn not transition metals

A

They don’t form a stable ion with in incomplete d sub shell

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4
Q

What are the four characteristic properties of transition metals

A

Form coloured compounds

Variable oxidation state

Catalysts

Form complex ions

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5
Q

What do the characteristic properties of transition metals arise due to

A

Incomplete d sub shell

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6
Q

Complex ion

A

Central metal ion surrounded by ligands

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7
Q

Ligands

A

A molecule/ion that forms a coordinate bond with a transition metal by donating a pair of electrons

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8
Q

3 types of ligands

A

Monodentate, bidentate and multidentate

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9
Q

Monodentate ligands

A

Molecules/ions that can donate one electron pair to the central mental ion to form one coordinate bond

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10
Q

Bidentate ligands

A

Molecules/ions that can donate 2 electron pairs to the central metal ion to form 2 coordinate bonds

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11
Q

Multidentate ligands

A

Molecules or ions that can donate more than 2 electron pairs to the central mental ion to form more than 2 coordinate bonds

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12
Q

Coordination number

A

The number of coordinate bonds to the central metal atom/ion

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13
Q

What is coordination number not necessarily the same as

A

The number of ligands

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14
Q

When is coordination number the same as number of ligands

A

In monodentate ligands

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15
Q

What are the two common shapes of complex ions

A

Octahedral and tetrahedral

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16
Q

What 2 other shapes are also sometimes complex ions

A

Square planar and linear

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17
Q

Why do complexes containing water and/or ammonia ligands usually have an octahedral shape

A

Because they usually have a coordination number of 6

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18
Q

Why do complexes containing chloride ligands usually have a tetrahedral shape

A

They usually have a coordination number of 4

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19
Q

Why do complexes of copper and silver usually have a linear shape

A

They usually have a coordination number of two

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20
Q

What are ligand substitution reactions

A

Reaction where one ligand is replaced by another

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21
Q

Why does the coordination number and shape not chance when a ligand substitution reaction occurs between NH3 And H2O

A

They are similar in size

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22
Q

equation for aqueous cobalt salts reacting with excess ammonia (all 6 water ligands replaceed)

A

[Co(H2O)6]2+ +6NH3 >< [Co(nh3)6]2+ +6H2O

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23
Q

colouur change when aqueous cobalt II salts react with excess ammonia

A

pink to pale brown

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24
Q

equation for aqueous copper II salts reacting with excess ammonia (4 water ligands replaced)

A

[Cu(H2O)6]2+ + 4NH3 >< [Cu(H2O)2(NH3)4]2+ +4H2O

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25
Q

colour change when aqueous copper II salts are reacted with excess ammonia

A

pale blue to dark blue

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26
Q

coordination number and shape for aqueous copper II salts reacting with excess ammonia (4 water ligands replaced)

A

6-6

octabhedral- octahedral

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27
Q

why do reactions involving chloride ligands involve a change in coordination number AND SHAPE

A

chloride ligand larger than NH3 and H2O

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28
Q

equation aqueous cobalt II salts reacted with conc hcl (all 4 ligands replaced)

A

[Co(H2O)6]2+ + 4Cl- >< [CoCl4]2- + 6H2O

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29
Q

COLOUR, COORD NUMBER AND SHAPE aqueous cobalt II salts reacted with conc hcl (all 4 ligands replaced)

A

colour: pink-blue
coord no- 6 to 4
shape: octahedral to tetrahedrial

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30
Q

haemoglobin: coordination number of iron II in haem unit

A

4

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31
Q

haemoglobin: shape around iron II i haem unit

A

square planar

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32
Q

haemoglobin: what does planar haem unit bound to and what does it bind to in body

A

complex protein called globin

both water and oxygen can bind to iron II as ligands

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33
Q

haemoglobin: what happens inthe lungs as a result of the concentration of oxygen being high

A

equilibrium shifts right and water ligands are substituted for oxygen molecules to form haemoglobin

34
Q

haemoglobin: which is the process of water/oxygen binding to haemoglobin reversed

A

when oxyhaemoglobin gets to where it is needed

35
Q

haemoglobin: what is the coordination number around iron in oxyhaemoglobin

A

6

36
Q

haemoglobin: what can haemoglobin substitute H2O ligands for when carbo monoxide is inhaled

A

Co

37
Q

haemoglobin: why is carbon monoxide considered toxic

A

bond between carbon monoxide and iron II is very strong and not readily revewrsed

preventsw oxygen being bonded to haemoglobin

38
Q

why are enthalpy changes usually quite small in ligand substitution reactions

A

often little change in number and types of bond present

39
Q

What happens when reactions occur that substitute bidentate and multidentate ligands for monodentate ligands

A

Complex formed often very stable and reaction hard to reverse

40
Q

When is a reaction feasible in terms of energy

A

If free energy, delta G, is negative

41
Q

What does delta G equal

A

Delta H - T delta S

42
Q

Why is there a large increase in entropy of a reaction when there is an increase in moles

A

Disorder is increased

43
Q

Chelate effect

A

Multidentate and bidentate ligands replace monodentate ligands to form complexes

44
Q

Why are transition metal ions coloured

A

Because they have an incomplete d sub shell

45
Q

What do all the d orbitals in a transition metal atom have exactly the same

A

Energy

46
Q

Why do complex ions have some orbitals with more energy than other

A

Interactions between ligands and electrons in d orbitals gives some more energy than others

47
Q

What does how the orbitals split depend on

A

The coordination number of the complex

48
Q

What are electrons promoted from and to when visible light is absorbed

A

Electrons promoted from lower energy (ground state) to higher energy (excited state)

49
Q

When transition metal ions absorb visible light corresponding to a colour this colour is…

A

Missing from the spectrum

50
Q

Why is the complementary colour to the one hat is absorbed seen

A

The remaining colours are transmitted

51
Q

What does the frequency of light absorbed depend on

A

The size of the energy gap

52
Q

Delta E equals

A

hv

53
Q

What is h

A

Plancks constant = 6.63x10-34 Js

54
Q

V equals (definition )

A

Frequency of light absorbed

55
Q

V equals

A

c/ŷ

56
Q

C equals

A

Speed of light = 3x10^8

57
Q

Ŷ equals

A

Wavelength of light

58
Q

what factors induce change of colour in reaction

A
  • change in coordination number
  • change in ligand
  • change in oxidation state
59
Q

why does change in coordination number induce colour change

A

splitting in the dorbitals is different in octahedral complexes than tetrahedral so when coordination number changes from 6 to 4 colour will also change

60
Q

example colour change due to change in coordination number equation

A

[Co(H2O)6]2+ + 4Cl- >< [CoCl4]2- + 6H2O

61
Q

colour change [Co(H2O)6]2+ to [CoCl4]2-

A

pink to blue

62
Q

what is a change in coordination number always accompanied by

A

a change in ligand

63
Q

why does a change in ligand induce a colour change

A

different ligands have different effects on the energies of d orbitals so when ligand changes the size of deltaE changes and hence the colour changes

64
Q

example nickel ligand changing from H2O to NH3

A

[Ni(H2O)6]2+ + 6NH3 >< [Ni(NH3)6]2+ + 6H2O

65
Q

colour change when nickel ligand changes from water to ammonia

A

green to blue

66
Q

why does a change in oxidation state induce a colour change

A

as oxidation state of metal increases so does size of energy gap, delta E. this leads to a change in colour

67
Q

example of irons ox state changing 2+ to 3+

A

[Fe(H2O)6]2+ > [Fe(H2O)6]3+

68
Q

what is spectrometry the study of

A

how electromagnetic radiation interacts with matter

69
Q

what is colorimetry a type of

A

spectroscopy

70
Q

what does a colorimeter measure and what does it give a measure of

A

measures amount of light absorbed by a solution and gives a measure of colour intensity

71
Q

what you must first do to find the concentration of an unknown

A

generate a calibration curve

72
Q

colourimetry experiment

A
  • create 4/5 standard solutions of known concentrations
  • select filter of complimentary colour and measure absorbance of known solutions
  • unknowns absorbance can be measured and conc found from calibration curve
73
Q

why must 4/5 standard solutions be made in colorimetry

A

to provide enough data to draw a line of best fit with confidence

74
Q

why must a filter be used in colorimetry

A

to select out the complementary colour, this is the light the sample absorbs

75
Q

stereoisomerism

A

compounds with the same structural formula but a different arrangement of atoms in space

76
Q

what type of complexes can exhibit stereoisomerism

A

square planar and octahedral

77
Q

when can cis-trans isomers form in square planar complexes

A

when it has 2 different ligands

78
Q

formula of cisplatin

A

[Pt(NH3)2Cl2]

79
Q

when can octahedral complexes exhibit cis-trans isomerism

A

2 different ligands- 4 of one and 2 of another

80
Q

which complexes can exhibit optical isomers

A

octahedral complexes containing bidentate ligands

81
Q

optical isomers

A

non superimposable mirror images

82
Q

Examples of complexes that exhibit optical isomerism

A

[Ni(en)3]2+ and [Co(C2O4)3]3-