transition metals Flashcards
what is a transition metal?
A metal that can form one or more stable ions with a partially filled d sub-shell
why aren’t scandium and zinc transition metals
as their stable ions don’t have any incomplete d sub shells
what is a complex
a metal ion surrounded by co-ordinately bonded ligands
what is a ligand
an atom ion or molecule that donates a pair of electrons to a central metal ion
Why are transition metals good catalysts
Because they can change their oxidation states by gaining or losing electrons within their d orbital this means they can transfer electrons to speed up reactions
what are the three things that change the colour of a transition metal ion
changes in oxidation state
changes in co-ordination number
changes in ligand
what is an autocatalyst
a product of a reaction that is a catalyst for the reaction itself
name a transition metal complex that occurs in the body
hameoglobin
name a transition metal complex that is an anti cancer drug
cis-platin
suggest a feature of silver chemistry which is characteristics of the transition elements
complexes
suggest a feature of silver chemistry which is not characteristic of the transition elements
colourless compounds
give the full electron configuration of a copper atom
ls2 2s2 2p6 3s2 3p6 3d10 4s1
What is meant by the term bidentate as applied to a ligand?
it has 2 lone pairs bond to the central metal ion
what is co-ordination number
the number of co-ordinate bonds
give on example of a bidentate ligand
C2O42-
what is a monodentate ligand
a ligand that can only form one co-ordinate bond
what is ligand substituion
when one ligand can be swapped for another ligand
almost always causes colour change
what happens to shape and co-ordination number if the ligands involved in ligand substiution are the same size
the shape and co-ordination number stays the same
what happens to shape and co-ordination of complex if the ligands in substituiton reaction are different sizes
co-ordination number changes as well shape
what is the colour of the precipitate formed when [Fe(H2O)6]3+ reacts with Na2CO3
a brown precipitate forms
along side bubbles
what is the colour of the solution formed when [Fe(H2O)6]3+ reacts with OH- or NH3
brown precipitate forms
what happens to the energy levels of a transition metal ion when a ligand binds
when ligands bond to the ions
some orbitals are given more energy than others.
this split the 3d orbitals into energy levels
electrons tend to occupy lower energy orbitals
to jump up to the higher energy orbitals they need energy equal to the energy gap they get the energy from visible light
what decides the colour of transition metal compounds
when visible light hits a transition metal ion
some frequencies are absorbed
as electrons jump up to higher orbitals
the frequencies absorbed depend on the size of the energy gap
the rest of the frequencies are reflected
these combine to make the complement of the colour of the absorbed frequencies
what is catalyst poisoning
impurities bind to the active site of the catalyst
reducing the surface area that the reactants can bind to
how can catalyst poisoning be prevented
by purifying the reactants
where does the reaction occur with a heterogenous catalyst
on the surface of the catalyst
how does a homogenous catalyst work?
they make an intermediate species
the reactants combine with the catalyst to form the intermediate species
which then reacts to form the products and reform the catalyst
what is chelation
the process by which a multidentate ligand replaces a monodentate ligand in forming co-ordinate bonds to a transition metal ion
