Transition Metals - the basics

With the written ISA coming up soon after we return, I thought it best to cover Transition Metals first, seeing as this is likely to be the basis of the paper.....

TRANSITION METAL = a metal that can form one or more stable ions with a partially filled d-subshell

- A d-subshell can fit 10 electrons in, so transition metals must form an ion that has between 1 and 9 electrons in this subshell
- It is this incomplete d-subshell that creates the key characteristics that define a transition metal
---> Scandium only forms one ion Sc³⁺, which has an empty d-subshell. Electron configuration for Sc is[Ar]3d¹4s² so for Sc³⁺it is just [Ar].
---> Zinc also only forms one ion, Zn²⁺, which has a full d-subshell. Electron configuration for Zn is

[Ar]3d¹⁰4s²so for Zn²⁺is just [Ar]3d¹⁰.

Transition Metals have four important characteristics in common:

1. Complex Formation

---> complex ion is formed when a transition metal is surrounded by ions or other molecules

2. Formation of Coloured Ions

---> majority of metal ions are coloured

3. Variable Oxidation States

---> have more than one oxidation state in their compounds and therefore take place in many redox reactions

4. Catalytic Activity

---> affect the rate of reaction without being used up or chemically changed themselves

LIGAND = an ion or molecule with a lone pair of electrons that can form a dative covalent bond

COMPLEX = central metal ion surrounded by ligands (2, 4 or 6)

CO-ORDINATION NUMBER = the number of dative covalent bonds formed

Unidentate = 1 dative covalent bond            e.g [Cu(CN)₆]^4-          [Co(OH)₂(H₂0)₂]

      

Bidentate = 2 dative covalent bonds            e.g [Co(en)₃]²⁺         [Cr(C₂O₄)]^3-

Hexadentate = 6 dative covalent bonds        e.g [Cu(edta)]^1-