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? Outline their angles
Tetrahedral = 109.5°
or
Square Planar = 90° & 180°
What shape do 6 co-ordinate bonds make? Outline the bond angles
Octahedral = 90° & 180°
What shape do 2 co-ordinate bonds make? Outline the bond angles
Linear = 180°
What type of ligand forms 2 co-ordinate bonds? Outline both of their names
Bidentate ligands/ Chelating ligands
Outline the Chelate effect
A metal ion increases in stability when a chelating ligand bonds to a metal ion forming one or more rings
Entropy also increases
Outline the equation for entropy with
ΔG = ΔH - TΔS
If ΔG is - then feasible
ΔG = Δ in Gibbs free energy (kJmol-1)
ΔH = Δ in enthalpy (kJmol-1)
T = Temperature (K)
ΔS = Δ in Entropy (JK-1mol-1)
Outline all the complimentary colours
Red & Green
Purple & Yellow
Blue & Orange
How do transition metals form coloured ions?
They absorb different wavelengths of light and reflect their complimentary colours
Outline 3 multidentate ligands and the number of ligands they have
- Ethane dioate = 2 ligands (X2 :O-)
- Haemoglobin = 6 ligands
- EDTA = 6 ligands (2 :N- + 4 :O-)
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- ions
Cr(+6) reduced to Cr(+3)
Outline the variable oxidation state use in redox titrations
e.g: acidified KMnO4 used to analyse Fe2+
Outline the coloured ions of MnO4-, Mn7+, and Mn2+
MnO4- = Purple
Mn7+ = Purple
Mn2+ = Purple pink
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 the colours of Fe2+ & Fe3+
Fe2+ = green
Fe3+ = brown
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
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
Outline the reacting ratio for the redox titration of Fe^2+ ions to MnO4- ions
Fe : MnO4-
5 1
Outline the reacting ratio for the redox titration of C2O4^2- ions to MnO4- ions
C2O4^2- : MnO4-
2.5 1
Outline the steps in the % by mass calculations of redox titrations
- Find the reacting ratio
- Find the moles of the reagent with the ratio of 1 (n=cv)
- Multiply this by the larger ratio to find the moles of the desired reagent
- Find the moles in the total volume
- Find the mass of the desired substance
- Find the % by mass (desired/total X 100)
Outline an example of homogeneous catalysis
Reaction of:
MnO4- + C2O4^2-
Both -ve so repulsion = large Ea to overcome
Fe2+/Fe3+ reduces Ea
