Transition Metals And Catalysts Flashcards
Define a transition metal
- a metal that forms an ion with a partially filled d - subshell
What are the features of a transition metal?
- they form coloured solutions
- they can accept or lose electrons
- they can be oxidised or reduced
- form shapes called complexes
- less reactive than alkali metals
Are transition metals catalysts, why?
- they are excellent catalysts as they can donate + accept electrons, change oxidation state
What type of ions do transition metals form?
complex ions
Define complex ions
a complex ion is a central atom or ion surrounded by ligands
- e.g. a vanadium ion is bonded to 6 water ligands by coordinate bonding
Define coordinate/dative bonding
shared pair of electrons which have both came from same atom
Define a ligand
ion or molecule with a lone pair of electrons that forms a coordinate bond with a central complex transition metal ion
What do catalysts do?
catalysts speed up rate of reactions by providing an alternative pathway with a lower activation energy
Define activation energy
minimum amount of energy needed by reactants for a collision to cause a reaction
What are the 3 steps of how catalysis happens?
Adsorption = reactants form weak bonds on surface of catalyst, because electrons are accepted and donated back
Reaction = takes place to form products
Resorption = product molecules are released from catalyst surface
This process offers an alternative pathway for the reaction with a lower activation energy so collisions with less energy will react
Explain why transition metals can act as catalysts
- they have a partially filled d - sub shell
- they can accept or lose electrons
- which means they can be oxidised and reduced
- so they can provide an alternative route for a reaction with a lower activation energy
Explain how a catalyst lowers the amount of energy needed for a reaction?
Adsorption = reactants form weak bonds on surface of catalyst, because electrons are accepted and donated back
Reaction = takes place to form products
Resorption = product molecules are released from catalyst surface
This process offers an alternative pathway for the reaction with a lower activation energy so collisions with less energy will react
What is the name of the process where a transition metal acts like a catalyst?
- the process is called the haber process
What is an example of the haber process in which a transition metal acts like a catalyst?
- the reaction bw nitrogen and hydrogen is catalysed by iron (Fe)
Define homogenous catalysts
Homogenous catalysts have the same physical state as reactants
