TRANSITION METALS Flashcards
TRANSITION METALS
Forms at least one stable ion with a partially filled D-sub shell
What are the 2 exseption ?
Sc- 1s2 2s2 2p6 3s2 3p6 4s2 3d1
Zn- 1s2 2s2 2p6 3s2 3p6 4s2 3d10
Key features of transition metals
Complex ion
Coloured ion
Catalytic properties
Variable oxidation state
What is a coordinate bond
Shared pair of e- which both come from same atom
Ligand definition
Ion or molecule eith a lone pair of e- which can form a coordinate bond with a transtiom metal ion
Coordinate number definition
Number kf coordinate bonds a transition metals ions forms
Complex ion definition
Transition metals ions form surrounded by ligands
Monodentate ligands example
H2O:
-:CN
:NH3
-:OH
CL:-
Bidentandate ligands example
1,2-diaminoethane
Ethanedioate ion
How many bond does EDTA4- form
6
What is the chellate effect
Occurs when a monidentate ligand substituetes by bidentate
If there is an increase in moles on the products side
Entropy AS decreases as more disorder
So reaction is feasible
How does HB work
O2 forms a coordinate bond to Fe2+ in haemoglobin enabling oxygen to be transported in the blood
CO toxic because CO bind more strongly to the Fe2+ in haemoglobin this orevents oxygen from bonding to Fe2+ causing soffication
Difference between cis/trans
Trans- 180 degrees between ligands
Cus - 90 degrees between ligands
How does plactin works
Binds to DNA in cancerous cells
Stops cell replication
Preventing DNA. From unwinding so cancerous cells cant replicate which prevents spreading of cancerous celks
Rormation of coloured ions
Due to patrtially filled d sub-shell absirb some of the colours from white light and reflects other
ROY- low energy
BIV- high energy
Why are some complexes colourless
No e- in d shell
/
Full d-sub shell
What causes alterstion of a compund colour
Change in ligands
Changd in oxidation state
Change in shape
Change in coordination number
How to find concentration of unkown sample form calibration curve
Measure absorbance for a range of known concentration
Plot a graph of concentration against absorbance/transmission
Read value of the concentration for measured absorbance from graph
What is a catalyst ?
Substance increases rate of reaction of a chemical reaction without being used up
How do catalust work?
Provides an alternative pathway with lower activation energy
Heterogeneous catalyst
Catalyst is in a different phase to the reactants
Homogeneous catalyst
Catalyst in same phase to the reactant
How xo heterogenous catalyst work
Reactant adsorb onto surface if catalust on active site
Reaction occurs on surface of catalyst
Products desorb form surface of catalyst
How to make catalyst more efficient? (2)
Increase surface area
Spread catalust over aninert support medium
Why dont catalyst last forever?
Immpurities can blocj active sites
Prevents reactants from adsorbing
Purifying reactants in the best way to prevent poisoning
Why is rate slow initially
No catalyst initially
2 negatively charged reactants collide with very high Ea
As reactant that act as catalyst formed rate increases as reaction is being increasingly catalysed
Rare then decreases and levels off as reactant get used up
Small E ROY ABS
Small AE between d sub shell
Low energy light
Will be absorbed to excite the e-
Blue indingo purple will be reflected
Big E BIV abs
Large AE between d subshell
High energy lost
Will bd absorbed to excite e-
Red yellow oranfe will be reflected
Harber process
Equations + catalyst
Catalyst: iron
N2(g) +3H2(g) <———> 2NH3(g)
Contact process
Equation + catalyst
Catalyst: V2O5
SO2(g) + V2O5(s) <——-> SO3(g) + V2O4(s)
2V2O4(s) +O2(g) <———-> 2V2O5(g)
Overall equation
2SO2(g) +O2(g) ————> 2SO3(g)
Manufucture of methanol
Catalust + equation
CH4(g) + H2O(g) ———-> CO(g)+ 3H2(g)
Catalyst: Cr2O3
CO(g) + 2H2(g) ———-> CH3OH(g)
uncatalyzed reaction
Catalyst + equation
2MnO4-(aq) + 16H+(aq) + 5C2O42-(aq) → 2Mn2+(aq) + 8H2O(l) + 10CO2(g)
Catalyst Mn2+
4Mn2+(aq) + MnO4-(aq) + 8H+(aq) → 5Mn3+(aq) + 4H2O(l)
2Mn3+(aq) + C2O4 2-(aq) ——> 2CO2 + 2Mn2+
Homogeneous catalyst
S2O82-(aq) + 2I-(aq)→2SO42-(aq) + I2(aq)
Catalyst:Fe2+
S2O82-(aq) + 2Fe2+(aq)→2SO42-(aq) + 2Fe3+(aq)
2I-(aq) + 2Fe3+(aq)→I2(aq) + 2Fe2+(aq)
