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OCR Chemistry A > 5.3 - Transition Metals > Flashcards

5.3 - Transition Metals Flashcards

1
Q

Transition metals

A

Elements that can form stable ions with an incomplete d sub shell

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2
Q

Why are Sc and Zn d-block elements but not transition metals

A

Sc^3+ ions have an empty 3d sub-shell and Zn2+ have a completely full subshell

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3
Q

Properties of transition metals

A

Variable oxidation states
Catalytic action
Coloured compounds
Formation of complexes

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4
Q

Complex ion

A

Metal ion surrounded by co-ordinately bonded ligands

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5
Q

Coordinate bond

A

Covalent bond in which both electrons in the shared pair come from the same atom

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6
Q

Coordination no.

A

No. of coordinate bonds to ligands that surround a transition metal ion

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7
Q

Ligand

A

An ion/molecule that forms a coordinate bond w/ a transition metal by donating its lone pairs (acts as a base)

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8
Q

Unidentate/monodentate

A

Ligand that can only form one coordinate bond

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9
Q

Examples of unidentate ligands

A 
H2O
NH3
Cl-
OH-
CN-
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10
Q

Bidentate

A

Ligand that can form two coordinate bonds by donating two lone pairs to central metal ion

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11
Q

Multidentate

A

Ligand that can form >1 coordinate bonds

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12
Q

What does coordination no. depend on

A

Size and electronic configuration of the cation

Size and charge of the ligands

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13
Q

Common coordination no.

A

6, 4, 2

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14
Q

Octahedral complexes

A

6 coordinate bonds (90 degrees)

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15
Q

Drawing 3D octahedral complexes

A

2 on the plane
2 going back into the plane
2 coming out of the plane

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16
Q

Tetrahedral complexes

A

4 coordinate bonds (109.5 degrees)

Usually chloro complexes

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17
Q

Drawing 3D tetrahedral complexes

A

2 on the plane
1 going back into the plane
1 coming out of the plane

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18
Q

Square planar complexes

A

4 coordinate bonds (90 degrees)

Requires TM w/ a 3d8 subshell e.g. Pt

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19
Q

Drawing 3D square planar complexes

A

2 going back into the plane

2 coming out of the plane

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20
Q

Cis trans isomerism in transition metal complexes

A

Only occurs in octahedral or square planar

Need two ligands that are different to the rest

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21
Q

Optical isomerism in TM complexes

A

Occurs in octahedral complexes w/ bidentate ligands

Can also be cis/trans

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22
Q

Highest oxidation no. for Sc

A

3+

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23
Q

Highest oxidation no. for Ti

A

+5

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24
Q

highest oxidation no. for V

A

+5

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25
Q

Highest oxidation no. for Cr

A

+6

26
Q

Highest oxidation no. for Mn

A

+7

27
Q

Oxidation no. for Fe - Zn

A

Maximum decreases from +6 to +2

28
Q

Catalysis reactions involving iron

A

Haber process

29
Q

Catalysis reaction involving V2O5

A

Contact process - 2 SO2 + 1/2O2 –> 2SO3
SO2 +V2O5 –> SO3 + V2O4
V2O4 +1/2 O2 –> V2O5

30
Q

Why are transition metals good catalysts

A

Ability to change oxidation state —> can be regenerated through oxidation or reduction of the intermediate
Can adsorb other substances on their surface and activate them (heterogenous)

31
Q

Why are complex ions w/ partially filled sub shells usually coloured

A

Electrons excited

Absorb energy from visible light spectrum

32
Q

Transition metal complexes in the body

A

Haemoglobin Fe^2+

33
Q

Transition metal complex use in medicine

A

Pt(NH3)2Cl 2
Cis platin (anti-cancer)
Binds to DNA preventing cell-division

34
Q

When are transition metals colourless

A

Filled d subshell

35
Q

How many coordinate bonds can EDTA 4- form

A

6
2 lone pairs on each N
4 on -COO

36
Q

Factors causing colour change in reactions of TM complexes

A

Ligand changes
Oxidation no. change
Coordination no. change

37
Q

Ligand substitution

A

One ligand in a complex is replaced by another

38
Q

Colour of hexaaquamanganese (II)

A

pale pink soln

39
Q

Mn(OH)2 ppt

A

Light brown

Insoluble in XS OH- or NH3

40
Q

Colour of Fe2+

A

Pale green soln.

41
Q

Fe(OH)2 ppt

A

Green ppt

Insoluble in XS OH- or NH3

42
Q

Colour of Fe 3+

A

Pale yelow soln.

43
Q

Fe(OH)3 ppt

A

Orange-brown ppt

Insoluble in XS OH- or NH3

44
Q

Colour of Cu2+

A

Blue soln

45
Q

Cu(OH)2 ppt

A

Pale blue
Insoluble in XS OH-
Soluble in XS NH3
[Cu(H2O)6]2+ + 4NH3 –> [Cu(NH3)4(H20)2}2+ + 4 H2O (dark blue soln)

46
Q

Colour of Cr3+

A

Violet soln

47
Q

Cr(OH)3

A

Gray-green ppt

48
Q

Cr3+ in XS OH-

A

Dark green soln

[Cr(OH)6]3-

49
Q

[Cr(H2O)6]2+ + 6NH3

A

[Cr(NH3)6}3+ + 6 H2O

Purple soln

50
Q

Ligand sub w/ HCl

A

[Cu(H2O)6} 2+ + 4Cl- [CuCl4]2- + 6 H2O
Reversible reaction
Yellow soln

51
Q

Why does only 4 Cl- ions sub for 6 H2O’s

A

Cl- ligands are much larger than H2O ligands and therefore less can fit around the central metal ion

52
Q

Why do you see a green colour during ligand sub w/ Cl- in Cu2+

A

Blue colour from hexaaquacopper (II) mixing w/ yellow colour from [CuCl4]2-

53
Q

Why do Fe2+. Fe3+ and Mn2+ react w/ NH3 the same way as OH-

A

NH3 + H2O —> NH4+ + OH-

The OH- then react to form a ppt

54
Q

en

A

H2NCH2CH2NH2

55
Q

Ethanedioate

A

(C2O4)2-

56
Q

Ligand sub in haemoglobin

A

Haemoglobin has one free ligand which can be used to pick up water or oxygen in oxygen-rich areas and oxygen is also easily lost in oxygen-poor areas
CO and CN can also bind and isn’t easily removed

57
Q

[Fe(H2O)6]2+ —-> [Fe(H20)6]3+

A

Add H+/MnO4-

58
Q

[Fe(H2O)6}3+ ——> [Fe(H2O)6]2+

A

Add KI

59
Q

Oxidising Cr 3+

A

H2O2/ OH-

60
Q

Reducing Cr2O7 2-

A

Zn/H+

61
Q

Reducing Cu2+

A

I-

Cu+ readily dissociates in aq

OCR Chemistry A (16 decks)

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