Transition Metals Flashcards
What is a transition metal?
D-block element that forms at least 1 stable ion with a partially filled d sub shell
Why are scandium and zinc not transition metals?
Neither scandium or zinc produce ions which have a partially filled d sub shell. (Sc d^0) (Zn d^10)
How does the d orbital fill up with electrons?
4s is the first to gain electrons due to a lower energy level. The the 3 d orbital starts to fill up with electrons. Once electrons are in the 3 d orbital, this orbital has a lower energy so the 4s electrons are also lost first.
What are some physical properties of transition metals?
All metals are shiny with a high density, melting and boiling point.
When they are solid they form giant metal lattices with delocalised electrons and therefore can conduct electricity.
What are some chemical properties of transition metals?
All transition metals have more than one oxidation state.
They all form 2+ ions from losing their 4s orbital.
Highest oxidation states will readily accept electrons and become reduced making them powerful oxidising agents.
What are the main characteristic properties of transition metals?
Form complex ions
Form coloured ions
Have variable oxidation states
Catalytic activity
What is disproportionation?
A process where a species is both oxidised and reduced in the same reaction
Eg. Hit dilute sulphuric acid and copper oxide forms a blue copper sulphate solution and brown copper precipitate as the copper is oxidised and reduced.
How do transition metals form coloured compounds?
When light passes through a solution of transition metals, the ions will absorb some wavelengths of light. Due to the splitting in the d orbital in an ion complex an electron may get promoted up to the higher energy level as the ions absorb light producing a colour.
How do transition metals act as catalysts?
They provide a surface for the reactions to take place on.
Many oxidation numbers and therefore can bind to reactants and form intermediates.
What transition metal catalyst are used in industrial processes?
Harder process- Iron (II) catalyst
Contact process- (vanadium catalyst)
Decomposition of hydrogen peroxide- manganese catalyst
Hydrogen production-copper sulphate catalyst
What are complex ions?
Formed when a central metal is surrounded by ligands or datively coordinate bonding to the metal ion.
Formed when a transition metal is present in a solution
What is a ligand?
A molecule or ion which can donate a pair of electrons to form a dative covalent ( coordinate) bond
What is the coordination number?
The number of coordinate bonds to the metal ion in a complex.
Give examples of ligands and state their formula and charge.
Water (:OH2) - neutral
Ammonia (:NH3) - neutral
Thiocyanate (:SCN^-) - -1
Cyanide (:CN^-) - -1
Chloride (:Cl^-) - -1
Hydroxide (:OH^-) - -1
What is a monodentate ligand?
Give examples
A ligand which is able to form 1 lone pair of electrons and from 1 coordinate bond.
Eg H2O NH3 Cl^-
Why is a chloride ligand only able to get 4 chloride molecules around the central atom?
Chloride ligand is larger than water and ammonia and hence will only be able to fit 4 chloride ions around the central metal ion.
What are bidentate ligands?
Give examples
Can donate 2 lone pairs of electrons from different atoms within the ligand to form 2 coordinate bonds
Eg ethane-1,2-diamine (en)
C2O4^2-
What are multidentate ligands?
Give examples
Ligands which can donate multiple lone pairs of electrons
Eg EDTA ——> EDTA^4- has 6 lone pairs
Hexadentate ligand
What is the main use of EDTA?
Used to bind to metal ions to decrease their concentrations
What shape is formed by a complex with 2 coordinate bonds?
Linear shape
[Ag(NH3)2]^2+
What shape is formed by a complex with 4 coordinate bonds?
Tetrahedral shape
Chloride ions
What shape is formed by a complex with 6 coordinate bonds?
Octahedral shape
Water and ammonia
(Most common shape)
What is special about ligand exchange between NH3 and H2O?
This exchange occurs without s change of s coordination number
What happens when a H2O ligand is exchanged by Cl-?
Involves a Change in the coordination number since chloride ions are a lot larger