Unit 1 Topic 4 ✓ Flashcards
Inorganic Chemistry: Transition metals
What is a d block transition element?
A d block transition element is a metal with an incomplete ‘d’ sub-shell in at least one of their ions. It gives them distinctive properties
NOTE: Zinc and scandium ions dont have this
Which transition metals (2) do not follow the Aufbau principle?
(Aufbau principle states that electrons will fill orbitals in order of increasing energy)
Chromium and Copper
NOTE: Chromium and copper’s 3d shell is more stable this way
What are the main properties of Transition metals? (4)
- Form coloured ions
- Form complexes
- Have variable oxidation states
- Show catalytic activity
Which two transition metals are atypical? Why?
Scandium and Zinc are atypical transition metals.
They don’t form coloured ions, they only have one oxidation state and their ion (singular) does not have an incomplete d subshell
What is the Oxidation state of an element?
(The oxidation state is the same as the oxidation number)
The oxidation state of an element is the total number of electrons that have been removed from/added to an element to get to its present state
(Oxidation - loss of electrons, increase in oxidation number
Reduction - gain of electrons, decrease in oxidation number)
What is a Ligand?
A ligand is a molecule/negative ion with at least one non-bonding pair of electrons, which they donate into unfilled orbitals of a central metal atom/ion to form a dative covalent bond with the metal
What is a Monodentate ligand?
A monodentate ligand is a ligand that bonds to a metal ion using one atom to form one dative bond
(Mono - one)
(Theres also Bidentate - 2, and Hexadentate - 6)
What is a Polydentate ligand?
A polydentate ligand bonds to the central metal ion using several atoms to form several dative bonds
(Poly - many)
What is the Coordination number of a complex?
The coordination number of a complex is the total number of bonds from the ligand(s) to the central transition metal ion
(Coordination number is the main determinant of the complex’s shape)
What is a Chelating agent?
e.g. EDTA
A chelating agent is a chemical that ‘wraps around’ a metal to form a very stable complex, with many ions. It’s used to remove metals from water systems or in the treatment of heavy metal poisoning
e.g. The haem group in haemoglobin, or chlorophyl is a natural chelate
What is the Spectrochemical series?
The spectrochemical series is the ability of ligands to cause splitting of d-orbitals
REMEMBER: Learn the order of the ability of ligands
Why do some chemicals appear coloured?
Chemicals can appear coloured as when white light shines on them they may absorb some of the visible light, so they appear the colour of white light, minus any colour they absorbed. The light we see is the complementary colour to what was absorbed
e.g. If a chemical appears blue, it absorbed red light
What is the Crystal field theory? (CFT)
The crystal field theory is the breaking of orbital degeneracy (the orbital ‘splits’) in transition metal complexes due to the presence of ligands
NOTE: Lost degeneracy means they aren’t the same energy
What determines how a d-orbital splits? (3)
-The nature of the metal involved
- The metals oxidation state
- The nature of the ligand (crystal field strength varies)
What is a d->d transition?
A d->d transition is when an electron moves from one d-orbital to a higher energy d-orbital
What is the Spectrochemical series?
The spectrochemical series is a series showing the ability of ligands to cause splitting of d orbitals
NOTE: You must memorise the series (8 ligands)
What is Spectroscopy?
Spectroscopy is the analysis of the interaction between matter and any part of the electromagnetic spectrum
What is a Catalyst?
A catalyst is a chemical substance that, when added to a chemical reaction, doesn’t affect the thermodynamics of the reaction but increases the rate. It increases the rate by lowering the activation energy
NOTE: Activation energy is the minimum energy required for a reaction to proceed
Give 3 examples of Transition metal catalysts in industrial reactions -
- Iron granules (Haber processs)
- Vanadium (V) oxide (Contact process)
- Platinum guaze (Ostwald process)
What is a Homogeneous catalyst?
A homogeneous catalyst is a catalyst in the same state as the reactants
What is a Heterogeneous catalyst?
A heterogeneous catalyst is in a different state to the reactants
