2.5 Transition Metals Flashcards
What is the definition of a Transition Metal?
Contain an incomplete d subshell
What is the definition of a ligand?
Particle with a lone pair which forms a coordinate bond
What is the definition of a complex?
Metal ions with ligands coordinately bonded
What are the four key properties of transition metals?
-Colourful
- Complex ions
- Variable oxidative states
- Catalytic activity
What complex forms a linear shape?
Ag+
What causes complex to form tetrahedral shapes?
Large ligands e.g. Cl
What complex forms square planar shapes?
Pt 2+
What complexes form octahedral shapes?
Most complexes
What is a unidentate ligand?
A ligand which only forms one coordinate bond
What is a bidentate ligand?
Forms two coordinate bonds
What is a multidentate ligand?
Ligand which forms more than two coordinate bonds
What stereoisomerism features do transition metal complexes display?
- Geometric isomerism (Cis-trans isomerism)
- Optical isomerism
Why are complexes coloured?
- 5d orbitals split into two different energy levels
so
1. d electrons absorb different frequencies of white light
2. d electrons get promoted to higher energy levels
3. Colour seen is light transmitted and not absorbed by moving electrons
What is the link between the concentration of a solution and light absorbed?
The more concentrated a solution the more light absorbed
What are the uses of variable oxidation states?
- testing for aldehydes
- Oxidising alcohols
- Catalysis
- Redox titrations
What are the four different oxidation states of vanadium and what colour is each state?
VO2+ - 5+ (yellow)
VO 2+- 4+ (blue)
V 3+- 3+ (green)
V 2+- 2+ (Violet)
Why is dilute H2SO4 used when reacting KMnO4?
H2SO4 needed as Cl- would be oxidised if HCl used
Dilute because conc H2SO4 is an oxidising agent
What is the ratio when KMnO4 reacts with Fe2+?
5 Fe2+ : 1 MnO4-
What is the ratio when C2O42- reacts with MnO4-?
52O42- :2MnO4-
What is a heterogeneous catalyst?
Catalyst in different state than reactants
How do heterogeneous catalysts work?
At least 1 reactant is adsorbed onto surface
What is catalyst poisoning?
Substances bindin too strongly to active sites blocking them
Why do transition metals make good catalysts?
Variable oxidation states
