Chapter 23 & 24 - Transition Metals and their Reactions in Aqueous Solutions
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define a transition metal
An metal which can form at least one stable ion with a partially full d subshell of electrons
which d block elements are not transition metals and why
scandium and zinc scandium forms only one ion with a completely empty d shell and zinc forms one ion with a completely full d shell this doesnt fit the definition of a transition metal
what are the properties of transition metals
form complex ions can exhibit variable oxidation states can form coloured ions have catalytic properties
what is a complex ion
a transition metal ion with coordinate bonds to other ions or molecules
what is a ligand
an ion or molecule which can form coorinate bonds with transition metals it must have a lone pair of electrons
give some examples of monodentate ligands
H2O, NH3, Cl-, CN-
what is the coordination number
the number of coordinate bonds on the central metal ion
how can you decide the shape of a complex ion
when there are 6 ligands its octahedral when there are 4 ligands its either tetrahedral or square planar when there are 2 then its linear
give an example of tetrahedral complex ion
tetrachloride cuprate (II)
give an example of a linear complex ion
diamine silver (i)
give an example of a square planar ion
cisplatin which is platinum with 2 amine groups and 2 chloride groups
what is the difference in chemical properties between transplatin and cisplatin
cisplatin is used to treat cancer and transplatin can cause cancer
what is the difference in structure between transplatin and cisplatin
in cisplatin the amine and chloride are next to eachother and in transplatin they are opposite
in which kind of compex ions can stereoisomerism arise
in octahedral ions with 2 of the same group in square planar when there are 2 different pairs of ligands attatches
what are unidentate ligands
only donate one pair of electrons per ligand
what are bidentate ligands
ligands that form two coordinate bonds which are from two different atoms
give an example of 2 bidenate ions
ethane-1-2-diamine and ethanedioate
what is the charge and coordination number of EDTA
charge is 4 minus and forms 6 coordinate bonds
what is the chelate effect and why does it occur
when the entropy of a reaction increases due to a displacement reaction where unidentate ligands are replaced by multidentate ions reactions are more stable at higher entropy
describe the thermodynamic changes in a chelate reaction
the entropy is positive because there are more molecules on the products than the reactants the enthalpy is neglegible because the same number of coordinate bonds are broken as are formed therefore the free gibbs energy is always negative and the reaction is always feasible
why do chloride ions form 4 coordinate bonds
because chloride ions are really large so only four can fit around the central ion
what is the central ion is a haemoglobin
iron two plus
why are complex ions coloured
because the d orbital splits into two energy levels and electrons can absorb energy and jump to a higher energy level the colour corresponds to the energy difference between the two energy levels
Which transition element is commonly used as a catalyst in the Haber process for the manufacture of ammonia?
iron