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CHEMISTRY: INORGANIC > Transition Metals ( A-level only) > Flashcards

Transition Metals ( A-level only) Flashcards

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1
Q

What cause the characteristics of elements Sc –> Cu arise?

A

From an incomplete d sub-level in atoms or ions

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2
Q

What are the characteristics of transition metals?

A
  • complex formation
  • formation of coloured ions
  • variable oxidation
  • catalytic activity
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3
Q

Why is zinc not a transition metal?

A
  • zinc only forms a +2 ion
  • has a complete d orbital
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4
Q

What rule does Cu and Cr follow in the electronic configuration?

A
  • fill the 3d subshell fully and then 4s
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5
Q

What is a ligand?

A

molecule or ion that forms a co-ordinate bond with a transition metal by donating a pair of electrons

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6
Q

What is a complex?

A

A central metal ion surrounded by ligands

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7
Q

What is a co-ordinator number?

A

the number of co-ordinate bonds to the central metal atom or ion

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8
Q

What is co-ordinate bonding?

A

when shared pair of electrons in the covalent bond come from only one of the bonding atoms

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9
Q

What is monodentate?

A

one co-ord bond per ligand

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10
Q

What is bidentate?

A

two atoms with lone pairs can form two-co ordinate bonds per ligand

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11
Q

What is multidentate?

A

can form multiple coridante bonds per ligand

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12
Q

What is an example of a monodentate ligand/

A

H20, NH3, and CL-

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13
Q

What is an example of a bidentate ligand?

A

Ethanedioate
C2O4.2-

Ethane-1,2-diamine

NH2CH2CH2NH2

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14
Q

What does the bracket [] and () mean for transition metals?

A

[] - complex
() - ligand

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15
Q

What can H2O, NH3 and Cl− act as in transition metals?

A

Monodentate ligands

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16
Q

What is similar about ligands NH3 and H20?

A

Similar in size and uncharged

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17
Q

Will the co-ordination number change if NH3 replaces H20 ligand?

A
  • no as they are similar
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18
Q

What may be the problem when NH3 replaces H20 ligand using Copper?

[Cu(H2O)6]2+(aq) + 4NH3 (aq)

A

May be incomplete so produces [Cu(NH3)4(H2O)2]2+

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19
Q

What is the difference between the chloride ligands and other monodentatae ligands?

A
  • larger than the uncharged ligands H20 and NH3
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20
Q

What does the addition of high concentration of chliride ions to an aqueous ion cause?

A

Ligand substitution reaction

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21
Q

Formula of complex and colour: conc HCL to Cu

A

[CuCl4]2- yellow/green solution

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22
Q

Formula of complex and colour: conc HCL to Co

A

[CoCl4]2- blue solution

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23
Q

What are the two Bidentatae ligandsa and co-ordination number 6?

A

ethane-1-2-diamine
ethanedioate

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24
Q

What is the formula for ethane-1-2-diamine?

A

[Cr(NH2CH2CH2NH2)3]3+

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25
Q

What is the formula for ethanedioate?

A

[Cr(C2O4)3]3-

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26
Q

What is an example of a multidentate?

A

EDTA.4-

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27
Q

Describe how CO binds to haem?

A
  • toxic
  • can form a strong co-ordinte bond with
    haemoglobin
  • stronger bond than oxygen
  • replaces oxygen
  • attaching to haemoglobin
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28
Q

What is the Chelate effect?

A

bidentate/multidentate ligands substitute monodentate ligands
–> increases moles of products
–> increases entropy
–> highly feasible

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29
Q

What will make Free energy negative with the formula?

A

The entropy will be negative
Enthalpy is small

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30
Q

What is the mole ratio of EDTA with any metal ion?

A

1:1

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31
Q

What is the common shape that transition metal ions form?

A

octahedral complexes with small liagnds

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32
Q

What shape of complex does Cl- ligands form?

A

Tetrahedral
- larger so less space

33
Q

What shape of complex ion is cisplatin?

A

Square planar

34
Q

What shape of complex ion does Ag+ form?

A

Linear

35
Q

What isomerism can complexes show?

A

Cis-trans isomerism
Optical isomerism

36
Q

Cis isomerism is when the molecules are on the ____ side

A

Same

37
Q

Trans isomerism is when the molecules are on the ______ side

A

different

38
Q

Which ligands show cis-trans isomerism?

A

Monodenatate

39
Q

What type of ligands show optical isomerism?

A

Bidentate ligands

40
Q

What are optical isomers?

A

Non-superimposable mirror images

41
Q

Colour changes arise from changes in?

A
  1. oxidation state
  2. co-ordination number
  3. ligand
42
Q

Why do transition metals form coloured complexes?

A
  1. 5d orbitals split into different energy levels
  2. Frequency of light is absorbed to excite the electrons from ground state to an excited state
  3. Frequency of light that is not absorbed is that colour that we see
43
Q

What are the two equations for the amount of energy absorbed due to light?

A

Delta E = h x v

h= plancks constant (J s)
v= frequency ( unit s-1)

Delta E = hc/λ

c= speed of light 3.00 x 10^8
λ = wavelength of light absorbed

44
Q

How does altering the ligand or co-ordination number cause a colour change?

A
  • alter the energy split
  • between the d -orbitals
  • changes the Energy absorbed
  • hence change the frequency of light absorbed
45
Q

Why does Sc^3+ not have colour?

A
  • ion hasnt got any D-block electronds left to move around
  • no energy transer equal to that visble of light
46
Q

Why does Zn^2+ amd Cu^+ not show colour?

A

their electronic shell is full
no space for electrons to transfer
no transfer of energy equal to visible light

47
Q

Describe the method of spectroscopy

A
  1. Add an appropriate ligand to intensify colour
  2. Make up solutions of known concentration
  3. Measure absorption or transmission using colorimeter
  4. Plot graph of absorption vs concentraiton
  5. Measure absorption of unknown and compare
48
Q

What is variable oxidation?

A

one element can exist in a range of oxidation states

49
Q

What influences the redox potential for a transition metal ion changing from a high to low oxidation state?

A

pH and ligand

50
Q

How many oxidation states does vanadium has?

A

Four main oxidation states

51
Q

What vandium ion has a +4 oxidation state?

A

VO^2+

52
Q

Which vanadium ion has vanadium’s oxidation state as +5?

A

VO2^+

53
Q

What colours are the four main oxidation states for vanadium?

remember mnemonic

A

YOU BETTER GET VANADIUM

VO2+ Oxidation state +5 ( a yellow solution)

VO2+ Oxidation state + 4 (a blue solution)

V3+ Oxidation state + 3 (a green solution)

V2+ Oxidation state + 2 (a violet solution)

54
Q

What will happen in the addition of zinc to vanadium (V) in acidic solution?

A

Reduces the vanadium
down through each successive oxidation state
yellow blue green violet/purple

55
Q

What does zinc act as in the reaction with vanadium (V) in acidic solution?

A

Strong reducing agent

can reduce most transition metals from high oxi state to low oxi state

56
Q

How does the tollenes test work in reference to [Ag(NH3)2]+?

A
  • used to distingush aldehyde and ketone
  • reduction of [Ag(NH3)2]+ by aldehydes to make silver
57
Q

What is the manganate ion?

A

MnO4-

58
Q

What is the maganese ion usually used in redox titrations?

A

Mn2+

59
Q

What is the half equation for maganate oxide?

A

Mn04- + 5e- + 8H+ —-> Mn2+ + 4H20

60
Q

What is the inital colour of Maganate?

A

Purple

61
Q

What is the final colour of manganate that should be seen in the flask when reduced in titration?

A

Pale pink/colourless

62
Q

What are the two ions used in redox titrations for maganate?

A

Fe2+

C2O4^2-

63
Q

What is the half equation for Fe2+?

A

Fe2+ —-> Fe3+ e-

64
Q

What is the half equation for C2O4^2-

A

C2O4^2- —-> 2CO2 + 2e-

65
Q

What acid do you use for manganate titrations and why?

A

Dilute sulfric acid to supply the 8H+ ions. Does not set up alternative redo reactions.

66
Q

What happens if insufficent acid is added to managante titration?

A

Causes production of MnO42 than Mn2+

it will mask the colour change and lead to greater volume of manganate being added the titration

67
Q

Why is concentrated HCL not a acid used in manganate redox titration?

A

It cannot be conc HCl as the Cl-
ions would be oxidised to Cl2 by MnO4-
- the EMF for MnO4- is greater that CL-

  • greater volume of manganate being used and posionius Cl2 is made
68
Q

Why can’t nitric acid be used as a acid in redox titrations?

A

It acts as oxidising agent for Iron.
Fe2+ –> Fe3+

Leads to smaller volume of manganate being used as less concentration of Fe2+ as it has reacted already.

69
Q

What is the half equation for hydrogen peroxide?

A

H2O2 —> O2 + 2H+ 2e-

70
Q

Why is heat added to reaction of C2O4^-2 and MnO4-?

A

Both ions are negative so naturally repel

slow reaction

heat increases the rate

71
Q

What acts as a catalyst in MnO4- redox titration with C2O4-?

A

Mn2+

production speeds up the rate of reaction –> autocatalysis

faster colour change as time goes on

72
Q

How do catalysts increase the rate of reaction?

A

Providing an alternative pathway with a lower activation energy

73
Q

What is a heterogenous catalyst?

A

Is in a different phase from the reactants

74
Q

What is a homogenous catalyst?

A

The same phase as the reactants

75
Q

Where does reaction occur with heterogenous catalysts?

A

Usually at the surface of the catalyst

76
Q

Describe the steps in heterogenous catalysis?

A
  1. Reactants form bonds with atoms at active sites on the surface of the catalyst so They are adsorbed.
  2. As a result bonds in the reactants are weakened and break
  3. New bonds form between the reactants held close together on a catalyst
  4. This weakens bonds between product and catalyst and product desorbs
77
Q

How does surface area help Catalysts?

A

Improve its effectiveness

Support medium used to maximise surface area and minimise cost

78
Q

How does iron catalyst in Haber process work efficiently

A

Used in pea sized lumps so larger surface area or support medium

79
Q

How can catalyst become poisoned?

A

By impurities
Meaning active sites are then blocked

CHEMISTRY: INORGANIC (6 decks)

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