1. Acid Base Character of period 3

2. The Period 3 Oxides
Element
Formula of oxide
Reaction of oxide with water
Acid/base nature
Sodium
Na2O
Na2O + H2O  2NaOH
Strongly basic
Magnesium
MgO
Slight: MgO + H2O  Mg(OH)2
Weakly basic
Aluminium
Al2O3
Amphoteric
Silicon
SiO2
Very weakly acidic
Phosphorous
P4O10
P4O H2O  4 H3PO4
Strongly acidic
Sulphur
SO2
SO3
SO3 + H2O  H2SO4
Chlorine
no direct reaction but:
Cl2O7
Cl2O7 + H2O  2 HClO4
Argon
no oxides
There is a gradual transition from basic to acidic character, reflecting a gradual transition from metallic to non-metallic nature

3. Lesson 6
Transition Metal Complexes - Introduction

4. Lesson 6: Transition Metal Complexes -Introduction
Objectives:
Describe the properties of transition metals
Understand the term ligands
Understand and explain the formation of transition metal complexes

5. The Traditional Based on Mendeleev’s work. Easiest to use and display.

6. The Transition Metals
A transition metal is an element in which at least one ion has a partially filled d-orbital
For example, Cu2+: 1s2 2s2 2p6 3s2 3p6 (4s0) 3d9
Properties of the transition metals include:
Variable oxidation states (for example iron: Fe2+, Fe3+, Fe6+)
Formation of coloured compounds
Catalytic properties
Formation of complex ions

7. Scandium and Zinc
Although in the first row of the d-block, these are not transition metals.
To understand why, write the full electron configuration for:
Sc and Sc3+
Zn and Zn2+

8. Variable oxidation numbers (ions)
Transition metals have large numbers of electrons in d- orbitals,
This means the amount of energy required to remove the second electron is not much different to that required to remove the first and so on.
Some common oxidation states we need to know:
All of them in the +2 oxidation state
Cr(III), Cr(VI)
Mn(IV), Mn(VII)
Fe(III)
Cu(II)

9. Formation of complex ions
Ligands:

10. Ligands A ligand is a species with a lone pair Common ligands include:
Often negative ions
Common ligands include:
Water, H2O
Ammonia, NH3
Chloride, Cl-
Hydroxide, OH-
Cyanide, CN-
Thiocyanate, SCN-

11. Transition Metal Complexes
The lone pair on a ligand can form a dative covalent bond to a metal ion to form a transition metal complex.
This involves the ligands donating charge into the empty 4d and 4s orbitals (at least for the first-row of transition elements), not the partially occupied 3d orbitals.
[Fe(H2O)6] [Fe(CN)6]3-
[Cu(Cl)4] [Ag(NH3)2]+

12. Complex Ions
Transition metal ions in solution have a high charge density and attract water molecules to from coordinate bonds with the positive ions to form complex ions.

13. Formation of complex ions
The electron pair from a ligand can form coordinate covalent bonds with the metal ion to form complex ions.
A “coordinate covalent bond” is also known as a “dative” - a bond in which both shared electrons are supplied by one species.
ligand
coordinate covalent bond

14. Formation of complex ions
Coordination number: the number of lone pairs bonded to the metal ion. L: :L
Mn+
Shape: linear
Coordination # = 2

15. Formation of complex ions
Coordination number: the number of lone pairs bonded to the metal ion. L: :L
Mn+ :L L:
Shape: square planar
Coordination # = 4

16. Formation of complex ions
Coordination number: the number of lone pairs bonded to the metal ion. L ..
Shape: tetrahedral
Coordination # = 4
Mn+ L: :L .. L

17. Formation of complex ions
Coordination number: the number of lone pairs bonded to the metal ion. L .. L: :L
Shape: octahedral
Coordination # = 6
Mn+ L: :L .. L

18. Coordination number: the number of lone pairs bonded to the metal ion.
Examples: state the coordination numbers of the species below.
[Fe(CN)6]3-
[CuCl4]2-
[Ag(NH3)2]+ 6 4 2

19. Colored Complexes

20. Big Ideas
The d-sublevel splits into two sets of orbitals of different energy in a complex ion
Complexes of the d-orbital are colored, as light is absorbed when an electron is excited between d orbitals
The color absorbed is complimentary to the color shown.

21. Transition Metal Colour Chart
Configuration
Colour
Sc3+
[Ar]
None
Ti3+
[Ar]3d1
Violet
V3+
[Ar]3d2
Green
Cr3+
[Ar]3d3
Mn2+
[Ar]3d4
Pink
Fe3+
[Ar]3d5
Yellow
Fe2+
[Ar]3d6
Co2+
[Ar]3d7
Ni2+
[Ar]3d8
Cu2+
[Ar]3d9
Blue
Zn2+
[Ar]3d10
Colourless

22. Both are “clear.” Only the beaker on the left is “colorless.”
Colored Complexes
NOTE: it is important to distinguish between the words “clear” and “colorless.” Neither AP, nor IB, will give credit for use of the word clear (which means translucent) when colorless should have been used. Think about it, something can be pink and clear… colorless means something else.
Both are “clear.” Only the beaker on the left is “colorless.”

23. Visible Light Spectrum

24. Colour depends on two things overall.
The strength of the coordinate bond between the ligand and the central metal ion.
Ligands interact more effectively with the d-orbitals of ions with higher nuclear charge.

25. For Example [Mn(H2O)6]2+ and [Fe(H20)6]3+
Both have the same configuration, but the iron compound has a higher nuclear charge.
Thus it will react stronger with water ligands
Mg compounds are a pale pink and absorb light in the green region
Fe compounds are yellow/brown and absorb light in the blue range.

26. Charge Density of the Ligand
The spectrum of the copper complex formed four water ligands is a very light blue colour.
When mixed with NH3 ligand the solution colour is a darker blue.
NH3 has a greater charge density than water and produces a larger split in thed-orbitals.

27. Spectrochemical Series.
Arranges the ligands according to energy separation.
Ligand I-
Br-
S2-
Cl-
H20
OH-
NH3
CN- CO
Max Frequency
Longest
Increasing Wavelength
Shortest ΔE
weakest
ΔE Increasing
Strongest