Transition Metals Introduction

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Transition MetalsIntroduction
R W Grime Ripon Grammar School
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5.4.1 - ELECTRON STRUCTURES
4s fills and empties before 3d
Ar 4s2 3d6
Ar 4s1 3d10
Fe
Cu
Ar 3d5
Ar 3d10
Fe3
Cu
Ar 4s2 3d1
Ar 3d9
Sc
Cu2
Ar
Ar 4s2 3d10
Sc3
Zn
Ar 4s2 3d3
Ar 3d10
V
Zn2
Ar 3d3
Ar 4s1 3d5
V2
Cr
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5.4.1 - WHAT ARE TRANSITION METALS?
Transition metals are metals that contain an
incomplete d sub shell in atoms or ions.
Top row transition metals Sc Cu Zn is not a
transition metal (Zn Zn2)
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5.4.1 PROPERTIES OF TRANSITION METALS?
1) They form coloured ions.
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5.4.1 PROPERTIES OF TRANSITION METALS?
2) They form complexes (ligands form co-ordinate
bonds to the metal ion).
Cu(H2O)62
CuCl42-
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5.4.1 PROPERTIES OF TRANSITION METALS?
3) They exhibit variable oxidation states.
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5.4.1 PROPERTIES OF TRANSITION METALS?
4) They show catalytic activity.
e.g.
Ni margarine production V2O5 making SO3 for
H2SO4 Fe Haber process to make NH3 Pt,
Pd catalytic converters
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5.4.2 COMPLEX FORMATION
Ligand atom / ion with a lone pair that forms
co-ordinate bond to metal
Complex metal ion with ligands co-ordinately
bonded to it
Co-ordination number
number of co-ordinate bonds from ligand(s) to
metal ions
Lewis base
lone pair donor (ligands are Lewis bases)
Lewis acid
lone pair acceptor
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5.4.2 COMPLEX FORMATION
Lewis base
lone pair donor (ligands are Lewis bases)
Lewis acid
lone pair acceptor
H OH- ? H2O
Lewis base
Lewis acid
Ligands form co-ordinate bonds via lone pairs
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5.4.2 COMPLEX FORMATION
Unidentate ligands form one co-ordinate bond
e.g. H2O, OH-, NH3, CN-, Cl-
Cu(H2O)62
CuCl42-
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5.4.2 COMPLEX FORMATION
Bidentate ligands form two co-ordinate bonds
ethanedioate (C2O42-)
1,2-diaminoethane (en)
Cr(C2O4)33-
Cr(en)33
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5.4.2 COMPLEX FORMATION
Multidentate ligands form several co-ordinate
bonds
EDTA4-
e.g. Cu(EDTA)2-
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5.4.2 COMPLEX FORMATION
Multidentate ligands form several co-ordinate
bonds
porphyrin
e.g. haem
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5.4.2 COMPLEX FORMATION
Multidentate ligands form several co-ordinate
bonds
haemoglobin
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5.4.7 USES OF SOME COMPLEXES
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5.4.7 USES OF SOME COMPLEXES
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5.4.7 USES OF SOME COMPLEXES
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5.4.7 USES OF SOME COMPLEXES
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5.4.7 USES OF SOME COMPLEXES
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5.4.7 USES OF SOME COMPLEXES
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5.4.7 USES OF SOME COMPLEXES
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5.4.3 SHAPES OF COMPLEX IONS
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5.4.3 SHAPES OF COMPLEX IONS
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5.4.3 SHAPES OF COMPLEX IONS
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5.4.3 SHAPES OF COMPLEX IONS
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5.4.3 SHAPES OF COMPLEX IONS
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5.4.3 SHAPES OF COMPLEX IONS
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5.4.3 SHAPES OF COMPLEX IONS
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5.4.3 SHAPES OF COMPLEX IONS

• For each of the following complexes
• Draw the complex.
• Name the shape.
• Show bond angles.
• Give the metal oxidation state.
• Give the co-ordination number.

• Ag(CN)2-
• Cr(NH3)63
• Ni(en)32

• Co(en)2Cl2
• Pt(NH3)2Cl2
• Fe(C2O4)34-

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5.4.3 SHAPES OF COMPLEX IONS
Linear 180º Ag 1 Co-ordination number 2
1
2
Octahedral 90º Cr 3 Co-ordination number 6
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5.4.3 SHAPES OF COMPLEX IONS
Octahedral 90º Ni 2 Co-ordination number 6
2
3
Ni
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Octahedral 90º Co 3 Co-ordination number 6
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5.4.3 SHAPES OF COMPLEX IONS
Tetrahedral 90º Pt 2 Co-ordination number 4
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Octahedral 90º Fe 2 Co-ordination number 6
4-
Fe
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5.4.3 SHAPES OF COMPLEX IONS
Geometric Isomerism
e.g. PtCl2(NH3)2
cis
trans
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5.4.3 SHAPES OF COMPLEX IONS
Geometric isomerism
e.g. CoCl2(NH3)4
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5.4.3 SHAPES OF COMPLEX IONS
Optical Isomerism
e.g. Co(en)33
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5.4.3 SHAPES OF COMPLEX IONS
Optical Isomerism
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5.4.4 FORMATION OF COLOURED IONS
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5.4.4 FORMATION OF COLOURED IONS
Once ligands bond, the five d orbitals are no
longer have the same energy.
Energy h?
Energy is absorbed to excite electrons from the
lower d orbitals to the higher d orbitals. This
energy is in the uv/visible region.
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5.4.4 FORMATION OF COLOURED IONS
Energy
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5.4.4 FORMATION OF COLOURED IONS
The colour you see is what is left after some
colours are absorbed by the metal to excite
electrons.
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5.4.4 FORMATION OF COLOURED IONS
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5.4.4 FORMATION OF COLOURED IONS
The size of the energy gap between the
d-orbitals, and so the colour is affected by
changes in
1) the metal
Cu(H2O)62
Fe(H2O)62
blue
green
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5.4.4 FORMATION OF COLOURED IONS
The size of the energy gap between the
d-orbitals, and so the colour is affected by
changes in
2) the oxidation state
Fe(H2O)63
Fe(H2O)62
green
pale violet
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5.4.4 FORMATION OF COLOURED IONS
The size of the energy gap between the
d-orbitals, and so the colour is affected by
changes in
3) the ligands
Cu(H2O)62
Cu(H2O)2(NH3)4 2
blue
deep blue
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5.4.4 FORMATION OF COLOURED IONS
The size of the energy gap between the
d-orbitals, and so the colour is affected by
changes in
4) the co-ordination number
Cu(H2O)62
CuCl4 2-
blue
yellow
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5.4.4 FORMATION OF COLOURED IONS
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5.4.4 FORMATION OF COLOURED IONS
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5.4.4 FORMATION OF COLOURED IONS
UV/Visible spectroscopy

• Frequencies at which complexes absorb can be
  measured by uv/visible spectroscopy.
• Light is passed through complex and the amount
  passing through measured.

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5.4.4 FORMATION OF COLOURED IONS
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5.4.4 FORMATION OF COLOURED IONS
Colorimetry

• The more concentrated the solution, the more it
  absorbs.
• This can be used to find the concentration of
  solutions this is done in colorimeters.
• For some ions, a ligand is added to intensify the
  colour.
• The strength of absorption of solutions of known
  concentration is measured and a graph produced.
• The concentration of a solution of unknown
  concentration can be found by measuring the
  absorption and using the graph.

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5.4.4 FORMATION OF COLOURED IONS
Colorimetry