The First Transition Series

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The First Transition Series

• Meaning and
• General features from
• Sc to Zn

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45.1 Introduction p.164 - 165

• Contain an incomplete d sub-shell
• in at least one of their oxidation state in
  compounds.
• Sc3 empty d sub-shell
• Zn2 d sub-shell filled completely
• Cu ion is not a transition metal ion
• Cu2 is as it has an incompletely filled d
  sub-shell

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45.2 General Features of thefrom d-block
elements Sc to Zn p.165 - 167

• Electronic configurations
• Based on Aufbau principle, Pauli exclusion
  principle and Hunds rule
• 4s orbital is filled before the 3d orbitals.
• Once the 4s orbitals is filled, its energy
  content increases and becomes higher than that of
  3d orbitals.
• Except for copper and chromium
• half-filled or fully filled d sub-shell gives
  rises to extra stability. 3d54s1 more stable
  than 3d44s2

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42.2 General features as metals p.167

• Good conductors of heat and electricity,
• hard, strong, malleable, ductile and lustrous.
• high melting and boiling points
• fairly low reactivity.
• Titaniumlarger atomic radius than iron less
  denseaircraft components

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45.2 General features as metals p.168

• Similar atomic radii
• replace
• formation of alloys
• Mn hardness and wearing resistant to its alloy.
• Cr inertness on stainless steel.

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45.2 General features ratomic / rionicp.169 -
170

• Smaller atomic radii than the s-block
• Not show much variation.
• Beginningincrease in effective nuclear charge
• Electron clouds are pulled closer
• increasing screening and repulsive effects
• effective nuclear charge to increase very slowly
• end... Screening and repulsive effect max.

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45.2 General featuresComparison of phy/chem
properties between d-block and s-block metals
p.170 p.171

• Electronic configurations and
• Atomic radii
• d-block metals have close-packed structures
• Densities increase general across the first
  series
• Decrease in atomic radius

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Comparison of ionization enthalpy between s-block
and d-block metals p.171

• Consider
• electronic configuration
• Nuclear charge
• Screening effect
• Atomic radius
• d-block metals are smaller in size
• removal of electrons does not involve the
  disruption of inner electron shell
• Addition of screening effect of the additional 3d
  electrons is so significant
• effective nuclear charge increases very slowly

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Comparison of ionization enthalpy between s-block
and d-block metals p.173

• A fully-filled or half-filled sub-shell
• Abnormally high ionization enthalpies
• First I.E. of Zn
• Second I.E. of Cr and Cu
• Third I.E. of Mn

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Comparison of EN betweens-block and d-block
metals p.173

• higher
• Smaller atomic radii
• attract the electrons in a bond more tightly
  towards themselves
• Slight increase
• gradual increase in effective nuclear charge and
  decrease in atomic radius
• Closer an electron shell .. more strongly the
  additional electron in a bond is attractedhigher
  E.N.

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Comparison of melting point and hardness between
d-block and s-block metals

• Higher
• Small in size
• Closely packed
• Both 3d and 4s electrons participate in metallic
  bonding
• By delocalizing into the electron sea
• Metallic bond strengthvery strong
• Harder / hardness dependent on the strength of
  the metallic bonds.

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Comparison of reactivity with water between
d-block and s-block metals

• React only very slowly
• Zn and Fe relatively more reactive (compare with
  other transition metals) with steam
• Zn(s) H2O(g) ? ZnO(s) H2(g)
• 3Fe(s) 4H2O(g) ? Fe3O4(s) 4H2(g)

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Question 1

• Why most transition elements can form alloys with
  each other?
• Why atomic radii of transition elements are
  similar?
• Effective nuclear charge increases slowly
• Why effective nuclear charge increases slowly
  across the period?
• Additional screening effect from additional d
  electron is significant

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Round 2 Question 1

• State four factor that will affect the value of
  I.E.
• Electronic configuration / nuclear charge/
  screening effect / atomic radii
• Why 2nd I.E. of Cr is abnormally high?
• Why EN of d-block element is higher than s-block?
• Why d-block metals are harder than s-block?

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Question 2

• State three principles in building up of
  electronic configurations of elements
• What is meaning of Aufbau principle?
• What is meaning of Pauli exclusion principle?
• What is Hunds rule

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Question 3

• State the electronic configuration of Sc
• What happen to the energy content of 4s orbital
  once 3d orbital is filled?
• State the electronic configuration of Cr
• State the electronic configuration of Cu

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45.3 Characteristic properties of the d-block
elements and compoundsVariable oxidation states
p.175

• 3d and 4s electrons are of similar energy
  levelsavailable for bonding
• form ions of roughly the same stability by losing
  different numbers of electrons
• 3 in scandium 2 in zinc
• Maximum oxidation never greater than the total
  number of 3d and 4s electrons

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45.3 Characteristic properties of the d-block
elements and compoundsVariable oxidation states
p.177

• Variable oxidation of Vanadium and their
  interconversions
• 2 to 5 (V2, V3, VO2, VO2)
• Reduced by Zn in conc. HCl VO2 ? V2
• Zinc acts as a strong reducing agent (Eo
  0.76 V)

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45.3 Characteristic properties of the d-block
elements and compoundsVariable oxidation states
p.179

• Variable oxidation of Manganese and their
  interconversions
• 2 to 7 (Mn2, Mn(OH)3, MnO2, MnO42-, MnO4-)
• Most stable 2
• MnO2 strong oxidizing agent
• Acidic medium Mn2
• Alkaline medium MnO2

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45.3 Characteristic properties of the d-block
elements and compoundsFormation of complexes
p.181

• Complexes or coordination compounds
• Dative covalent bonds
• Ligands ion or molecule lone pair of
  electrons
• CO, H2O, NH3 neutral ligands
• Cl-, CN-, OH- ionic ligands
• Cationic complex ion, neutral complex and anionic
  complex ion

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45.3 Characteristic properties of the d-block
elements and compoundsFormation of complexes
p.182

• Coordination number number of ligands bonded to
  this metal atom or ion
• Donation of lone pairs of electrons on the
  ligands, to the vacant, low energy orbitals on
  the central metal atom or ion
• Interact with orbitals
• Besides, small sizes, high charge of d-block
  metal ionsstrong polarization on the ligands
  formation of bond of high covalent character

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45.3 Characteristic properties of the d-block
elements and compoundsFormation of complexes
p.182
3 or 2
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45.3 Characteristic properties of the d-block
elements and compoundsNomenclature of complexes
p.183
3
Hexacyanoferrate(III) ( 6 ligands CN- Fe3)
How to name Fe(H2O)63? (6 ligands H2O Fe3)
Hexaaquairon(III)
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45.3 Characteristic properties of the d-block
elements and compoundsNomenclature of complexes
p.183
Rules of naming 1a. Cation before anion
Fe(H2O)6 Cl3 Hexaaquairon(III) chloride
K3 Fe(CN)6 Potassium Hexacyanoferrate(III)
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45.3 Characteristic properties of the d-block
elements and compoundsNomenclature of complexes
p.183
Rules of naming 1b. Ligands are named before the
central metal atom or ion, negative one (ligands)
first and then neutral one (ligands)
CrCl2(H2O) 4Cl Dichlorotetraaquachromium(III)
chloride CrCl2(H2O) 4 ? Cr3 with 2Cl-
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45.3 Characteristic properties of the d-block
elements and compoundsNomenclature of complexes
p.183
Rules of naming 2a. Anionic ligands end in o
(chloro / cyano) 2b. Neutral ligands (ammine /
aqua)
CrCl2(H2O) 4Cl Dichlorotetraaquachromium(III)
chloride CrCl2(H2O) 4 ? Cr3 with 2Cl-
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45.3 Characteristic properties of the d-block
elements and compoundsNomenclature of complexes
p.184
Rules of naming 3.a complex is anionic (end in)
ate 3.b complex is cationic or neutral
unchanged
K3 Fe(CN)6 Potassium Hexacyanoferrate(III)
Fe(H2O)6 Cl3 Hexaaquairon(III) chloride
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• Unit 45 Question 4
• Identify the oxidation number and the
  coordination number of the metal forming the
  complex ion

• K3Fe(CN)6
• K3CuCl4
• Ag(NH3)2NO3
• Answers
• a) 3 / 6 b) 1 / 4 c) 1 / 2

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Part 14 Further exercise 3a I PtCl2(NH3)4Br2 I
I PtBr2(NH3)4Cl2

• For each of the compounds above, what is
• (i) the oxidation number
• (ii) the coordination number
• (iii) the shape
• Answers a)i 4 in both ii) 4 in both
  tetrahedral

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45.3 Characteristic properties
complexesDisplacement of ligands and Relative
Stability of complex ions p.185
Why displacement tendency to donate unshared
electron to form dative bonds varies with
different ligands stronger ligand (e.g. CN-,
Cl-) can displace a weaker ligand
(e.g.H2O) Fe(H2O)62(aq) 6CN- ?
Fe(CN)64-(aq) 6H2O Hexaaquairon(II)
ion hexacyanoferrate(II) ion
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45.3 Characteristic properties
complexesDisplacement of ligands and Relative
Stability of complex ions p.186
What after displacement colours are related to
the types of ligands present. Equilibria set-up
overall stability constant, Kst Cu(H2O)42(aq)
4Cl- ? CuCl42-(aq) 4H2O Kst
CuCl42-eqm/ Cu(H2O)42eqm Cl-4
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45.3 Characteristic properties
complexesDisplacement of ligands and Relative
Stability of complex ions p.186

• About stability constant
• Larger the overall stability constant, more
  stable is the complex.(CuCl42- is stable than
  Cu(H2O)42 means CuCl42- has larger Kst)
• Stepwise stability constants are found to
  decrease from K1 to K4 (e.g. for CuCl42-)
• (due to) change from a cationic complex to anion
  complex electrostatic repulsion (increases)

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45.3 Characteristic properties
complexesp.189Stereostructures of tetra- / hexa-
coordinated complex
Spatial arrangement of ligands referred as
Stereochemistry Coordination number is determined
by size of the central metal atom number and
nature of vacant orbitals (available) Shape
tetrahedral square planar octahedral Isomers
structural isomers geometrical isomers
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tetrahedral
Shape tetrahedral square planar
octahedral Isomers structural isomers
geometrical isomers
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Square planar
Shape tetrahedral square planar
octahedral Isomers structural isomers
geometrical isomers
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Shape tetrahedral square planar
octahedral Isomers structural isomers
geometrical isomers
Octahedral
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Geometrical isomer Same chemical formula but
different arrangement of ligands in space
Shape tetrahedral square planar
octahedral Isomers structural isomers
geometrical isomers
Cis on the same side Trans on the different side
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Shape tetrahedral square planar
octahedral Isomers structural isomers
geometrical isomers
Structural isomer Same chemical formula but
different ligands bonded to the central metal
atom or ion e.g. Cr(H2O)6Cl3 and
Cr(H2O)5ClCl2
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Geometrical isomer Same chemical formula but
different arrangement of ligands in space
Shape tetrahedral square planar
octahedral Isomers structural isomers
geometrical isomers
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Geometrical isomer Same chemical formula but
different arrangement of ligands in space
Shape tetrahedral square planar
octahedral Isomers structural isomers
geometrical isomers
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Geometrical isomer Same chemical formula but
different arrangement of ligands in space
Shape tetrahedral square planar
octahedral Isomers structural isomers
geometrical isomers
fac-trichlorotriamminecobalt(III)
mer-trichlorotriamminecobalt(III)
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45.3 Characteristic properties Coloured ions
p.195crystal field theroy
3d orbitalsDegenerate ? Hydrated ? split d-d
transitionelectrons promoted from 3d at lower
energy level to those at higher energy level
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45.3 Characteristic properties Coloured ions
p.196crystal field theroy
Energy required for the d-d transition falls
within the visible light spectrum. This lead to
light absorption, and remainder of the visible
light is reflected.
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45.3 Characteristic properties Catalytic
properties p.200 Heterogeneous catalysis
Metal providing an active reaction surface for
the reaction to occur.
e.g. Fe in Haber process
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45.3 Characteristic properties Catalytic
properties p.201 Homogeneous catalysis
2Fe3 2I- ? 2Fe2 I2 2Fe2 S2O82- ? 2Fe3
2SO42- i.e. Fe3 changes the reaction pathway for
the reaction between I- and S2O82-.
e.g. Fe3 in reaction between I- and S2O82-.
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