Transition Metals Flashcards
Define Transition Metal
Metal atom with partially filled d subshell
What transition metals do we cover?
What is an exception that isn’t a transition metal?
Top row Sc-Zn
Zn exception 3d10 subshell for atoms & ions
How do transition metals form complexes?
Forms coordinate bond with ligand from e-s from ligand for dative bond
Define a Ligand
Particle with lone pair that forms a co-ordinate bond with metals
Define a Complex
Metal ion + ligand with a co-ordinate bond
Define co-ordination number
Number of co-ordinate bonds in a complex
Define a Lewis Base
Lone pair donor
Define a Lewis Acid
Lone pair acceptor
What shapes do 4 co-ordinate bonds make?
Tetrahedral mostly but sometimes square planar
What shape do 6 co-ordinate bonds make?
Octahedral
What shape do 2 co-ordinate bonds make
Linear
What type of ligand forms 2 co-ordinate bonds?
Bidentate ligands
How do transition metals form coloured ions?
They absorb different wavelengths of light
What does the colour of the transition metal ion depend on?
- The metal ion
- The Type of ligand attached
- The co-ordination number
- The oxidation state of the transition metal
What happens to transition metal d orbitals when ligands bond?
When ligands bond 5 d orbitals don’t have same energy
e- excited from lower d orbitals to higher d orbitals
How do coloured ions form?
Different energy of d orbitals is in the UV/Visible region -> d-d
Outline the Planck equation with units
E diff between 2 d-d orbitals (J) = Planck’s constant (6.63x10-34 Jhz-1) X frequency (hz)
E diff = hf
Outline the variable oxidation state use in Tollen’s reagent
Has [Ag(NH3)2]+
Ag (+1) reduced to Ag (0)
Outline the variable oxidation state use in Fehling’s solution
Contains Cu (+2) reduced to Cu (+1)
Outline the variable oxidation state use in acidified potassium dichromate
Has Cr2O7^2-
Cr(+6) reduced to Cr(+3)
Outline the variable oxidation state use in redox titrations
e.g: acidified KMnO4 used to analyse Fe2+
How do pH & ligands affect redox reactions?
Reduction of V (+5) to V(+2) due to an acid with Zn
Outline all the colour stages of Vanadium
V(+5) VO2 = Yellow
V(+4) VO^2+ = Blue
V(+3) V3+ = Green
V(+2) V2+ = Violet
Outline the anagram for the colour change of V
You
Better
Get
Vanadate
Outline how redox potentials impact oxidation states of transition metals
Lower O2 state = Reducing agent in acidic conditions
Higher O2 state = Oxidising agent in alkaline conditions
Define complete ligand substitution
Substitution of similar sized ligands -> entropy is the =
Define Partial ligand substitution
Substitution of different sized ligands -> entropy changes
Chelate
Define Heterogeneous catalyst
Catalysts in different phase to reactants (usually solid e.g: C2H4 + H2 -> C2H6
Define homogeneous catalysts
Catalysts that are the = phase as reactants (normally aq)
Define Adsorbed
Forms bond to the atoms in solid surface
Outline how Heterogeneous catalysts work in 3 steps
- Reactants adsorbed onto surface
- Weakens bonds
- brings molecules closer
- more favourable orientation - Reaction takes place
- Products desorbed (leave surface)
Outline how too strong of an adsorption impacts heterogeneous catalysis
Too strong (e.g Tungsten/W)
- Reactants can’t move round surface
-Products can’t desorb
Outline how too weak of an adsorption impacts heterogeneous catalysis
Reactants not adsorbed (e.g: silve/Ag)
Outline ideal adsorption for heterogeneous catalyst
Nickel and Platinum
Outline the characteristics of heterogeneous catalysts
Large SA
Spread thinly over ceramic honeycomb
