Chapter 23: Transition Metals Flashcards
Define a transition metal.
Forms an ion with a part full d sub shell of electrons.
What are the four main features of transition metals?
- Variable oxidation states
- Colour
- Catalysis
- Complex formation
When is a complex ion formed?
When a transition metal ion is surrounded by ions or other molecules, to collectively form Logan’s.
Define a ligand.
An ion or molecule with a lone pair of electrons that forms a coordinate bond with a transition metal.
Define co-ordination number.
The number of co-ordinate bonds to ligands that surround the d-block metal ion.
Is chlorine or ammonia a bigger ligand?
Chlorine is a bigger ligand, so fewer ions fit around the central ion.
Define multidentate ligands.
Have more than one atom with a lone pair of electrons which can bond to a transition metal ion.
Example of a multidentate ligand.
EDTA^-4
What is EDTA^-4?
Acts as a hexadentate ligand.
Uses lone pairs on four oxygen atoms and both nitrogen atoms.
What is a use of chelates?
Effectively remove d-block metal ions from solution.
What are chelates?
Complex ions with polydentate ligands.
Examples of bidentate ligands.
Ethanedioate ion.
Benzene-1,2-diol
Ethane-1,2-diamine
What are aqua ions?
When you dissolve the salt of a transition metal in water, the positively charged metal ion becomes surrounded by water molecules acting as ligands.
Why are transition metal compounds complexes formed?
1) They have part filled d-orbitals.
2) It is possible for electrons to move from one d-orbital to another.
3) In an isolated transition metal ion, all d-orbitals are of exactly the same energy, but in a compound the presence of other atoms nearby makes the d-orbitals have slightly different energies.
4) When electrons move from d-orbital to another of higher energy level. They often absorb energy in the visible region of the spectrum equal to the difference in energy between levels.
5) This colour is missing from the spectrum and you see the combination of colours that are not absorbed.
How does colorimetry work?
A light source and detector is used it measure the amount of light of a particular wavelength that passes through a solution. The more concentration the solution is, the less light is transmitted though the solution
