1.3 Transition metals Flashcards
Describe the d block transition metals
metals with an incomplete d subshell in at least one of their ions
What principle does the filling of d orbitals follow?
aufbau principle
-with the exception of chromium and copper atoms
Why do the d subshells of chromium and copper not follow the aufbau principle?
due to a special stability associated with the d subshell being half filled or completely filler
What happens when an atom from the first row of transition metals form ions?
it is the 4s electrons that are lost first rather then the 3d electrons
How can the oxidation number be determined?
- uncombined elements = 0
- single atom ions = same as the charge
- oxygen = -2
- hydrogen = +1
- neutral compound = all atoms must add up to 0
- polyatomic ion = equal the charge on the ion
What can a transition metal have?
different oxidation states in its compound
Explain colour changes in transition metals
Compounds of the same transition metal in different oxidation states may have different colours
What is oxidation?
an increase in oxidation number
What is reduction?
a decrease in oxidation number
What can changes in oxidation number of transition metals be used for?
to determine weather oxidation or reduction has occurred
What are compounds with metals in high oxidation states often?
Oxidising agents
What are compounds with metals in low oxidation states often?
Reducing agents
What are ligands?
- negative ions
- or molecules with non-bonding pairs of electrons
-that they donate to a central metal ion - forming dative covalent bonds
What can ligands be classed as?
- monodentate
- bidentate
- up to hexadentate
What is the coordination number?
the total number of bonds from the ligands to the central metal atom
Names and formulae can be written according to IUPAC rules for complexes containing what?
- Central metals that obey the normal IUPAC rules
- Copper (cuprate) and iron (ferrate)
- Ligands including water, ammonia, halogens , cyanide, hydroxide and oxalate
In a complex of a transition metal, what are the d orbitals no longer?
degenerate
When does the splitting of d orbitals to higher and lower energies occur?
When the electrons present in approaching ligands cause the electrons in the orbitals lying along the axes to be repelled
What are strong field ligands?
Ligands that cause a large difference in energy between subsets of d orbitals.
What are weal field ligands?
Cause a small energy difference between subsets of d orbitals
What is the spectrochemical series?
Ligands can be placed in order of their ability to split d orbitals
How can colours of many transition metal complexes be explained?
In terms of d-d transitions
When is light absorbed?
When electrons in a lower energy d orbital are promoted to a d orbital of higher energy
What is shown when light of one colour is absorbed?
the complementary colour will be shown
