Transition Metals Flashcards
Define a transition metal
Stable ions with partially filled d orbitals
What are the characteristics of transition metals?
They have no electrons in the 3d orbitals
Why are zinc and scandium not transition metals?
4s
Define ligands
They have many stable oxidation states
Define complex
Donates a lone pair of electrons to the central atom
What is a co-ordination number?
A central atom or ion surrounded with ligands
What is a monodentate ligand?
Number if co-ordinate bonds to the central atom/ion
State three examples of monodentate ligands
What are the similarities between NH3 and H2O?
Small ligands- H2O, NH3, OH-, CN-
Larger ligands- Cl-
Describe the change in co-ordination number and charge when H2O replaces NH3
No change
Why may a ligand substitution be incomplete?
Change in the co-ordination number
Give an example of a ligand larger than NH3 and H2O
Oxygen forms a co-ordinate bond to iron (II) in Haemoglobin, this enables oxygen to be transported in the blood
What changes when you replace H2O with Cl- ?
It replaces the oxygen co-ordinately bonded to Fe(II) in haemoglobin
Define bidentate ligand
Octahedral complexes that display cis-trans isomerism
State two examples of bidentate ligands
Electrons get excited by heat and radiation so some of the wavelengths of visible light are absorbed and the remaining are transmitted or reflected.
Define multidentate ligand
The d orbital electrons move from the ground state to an excited state when light is absorbed.
Give an example of a multidentate ligand
What is heam and example of?
Change in oxidation state.
Change in Co-ordination number
Change in ligand.
What is one role of O2 in the blood?
Use of radiation to determine the structure/identity of a molecule.
Define entropy
Measure of disorder that determines what reactions are feasible.
State the chelate effect.
A large increase in disroder/entropy when a bidentate ligand subs out a mondentate ligand.
What makes a reaction feasible?
When the products are less than the reactants therefore the reaction is more stable and entropically favourable.
This is an exothermic reaction.
Explain what kind of reaction is never feasible.
When the reactants are greater than the products, there’s an increase of energy in the system (endothermic) but a decrease in disorder but these two can not occur at once, therefore it’s not feasible.
State the role of a catalyst.
Speed up rate of chemical reactions- lowering the activation energy by providing an alternate pathway for molecules to travel though
What is a heterogenous catalyst?
A catalyst that is in a different phase from the reactants and the reaction occurs at active sites on the surface.
Give examples of two heterogeneous catalysts and what processes they are used in.
Fe in the Haber process
V2O5 in the Contact process.
What causes reduced efficiency in heterogeneous catalysts?
They can become poisoned by impurities that block active sites
Define a homogenous catalyst.
A catalyst that is in the same phase as the reactants.
State the equation of the catalyst used in the Contact process
State the equation of the catalyst used in the Haber process
What is amphoteric character?
When a metal hydroxide dissolves in both acids and bases.
How does V2O5 act as a catalyst in the contact process?
(Use equations)
How do Fe ^2+ ions catalyse the reaction between I- and S2O8^2- ?
(Use equations)
How do Mn^2+ ions autocatalyse the reaction between C2O4^2- and MnO4- ?
(Use equations)
