Topic 15- Transition metals Flashcards
What colour is produced when copper ions react with HCL?
Yellow solution
What is meant by the coordination number?
number of dative bonds in a complex
What colour precipitate is Iron(II) Hydroxide?
Green precipitate
What is the colour of solution of Hexaquacobalt(II)
Pink solution
Colour of tetraaminediaquacopper(II)
Dark Blue solution
What colour precipitate is Iron(III) hydroxide
Brown precipitate
Colour of V2+
purple
Colour of V3+
green
Colour of VO 2+
blue
What is meant by a Ligand?
a species which uses lone pair of electrons to form a dative bond with a metal ion
3 steps of Catalytic converters
-adsorption of CO and NO molecules onto the surface of the catalyst
-weakening of bonds and chemical reaction
-desorption of CO2 and N2 product molecules from the surface of the catalyst
Properties of transition metals
Have variable oxidation states
Good catalysts
Form coloured ions in solutions
Why do transition metals have variable oxidation states?
The outer electrons sit in the 4s and 3d sub shells which are very close in energy levels
Why is Scandium not a transition metal?
Forms Sc3+ ion only has one stable ion
Has an empty d-subshell
Why is zinc not a transition metal?
The Zn2+ ion forms a full d-subshell
Examples of bidentate ligands
Ethanedioate (C2O4 2-)
Ethane-1,2-diamine (NH2CH2CH2NH2)
Examples of multi dentate ligands
EDTA4- can form 6 bonds (coordination number of 6)
Haemoglobin shape
Octahedral
What can haemoglobin carry and replace the ligand with
Can replace H2O with O2 to form oxyhaemoglobin
Can also bond to carbon monoxide- harder to replace ligand because has a very strong bond
Square planar examples
Cis-Platin and Trans-platin (90 degrees)
When does the d-orbital split
When ligands begin to attach to the central metal ion
Why do colours show
When white light is absorbed from electrons in the ground state they become excited and move further up to their excited state. Drop back down to ground level releasing visible light on electromagnetic spectrum
What is colour dependent on?
The central metal ion
The type of ligand
The shape of the ligand
What do redox potentials tell us about transition metals?
Tells us how easy a complex is reduced
What is meant if a transition metal has a larger Ecell value?
It is unstable
Why are zinc ions colourless?
They have a full d-subshell and therefore electrons cannot be promoted
Equation for reaction between amphoteric chromium hydroxide with base (OH-)
Cr(H2O)3(OH)3 + 3OH- –> [Cr(OH)6]3+ +3H2O
Equation for reaction between amphoteric chromium hydroxide and acid (H+)
Cr(H2O)3(OH)3 + 3H+ –> [Cr(H2O)6]3+ +3H2O
Reaction between iodine and thiosulfate ions
2S2O3(2-) + I2 –> 2I- + S4O6(2-)
what colour is the [Co(Η2Ο)6]2+ ion
pink solution
what colour is the [CoCl4]2− ion
blue in solution
How V2O5 acts as a catalyst in the contact process
V 2 O 5 is used as a catalyst to reduce the higher temperature requirements and it increases the rate of reaction as well
colour of Cr2O7 2- (dichromate)
orange
colour of CrO4 2- (chromate)
yellow
colour of Cr3+
green
colour of Cr2+
blue
equilibrium reaction between chromate(VI) and dichromate(VI)
Cr2O7 2- + OH- <–> CrO4 2- + H+
Addition of acid to reaction between dichromate and chromate equilibrium
Will shift to the left, produce more dichromate
Addition of alkali to reaction between dichromate and chromate equilibrium
Will shift yo the right, produce more chromate ions
