- Created by: ava.scott
- Created on: 02-01-15 14:44
A D-block element- An element with its highest energy level electrons in the d-subshell.
A Transition element- an element which creates ions with a partially filled d-subshell.
Scandium and Zinc are not transition elements, as their d-blocks are completely empty/full.
A electron from the 4s subshell jumps up to the 3d subshell, to be more stable.
A electron from the 4s subshell jumps up to the 3d subshell.
Properties of transition elements
- high density
- high MP and BP
- Exist in giant metal lattices
- Variable oxidation states e.g. Fe2+/Fe3+
- Coloured compounds e.g. Cu2+ = blue
- Good catalysts NEXT PAGE
Catalysis and precipitation
Catalysts increase the rate of a chemical reaction by providing an alternative route for the reaction.
Transition metals provide a surface for the reaction to take place on. Reactants are adsorbed, and products desorbed.
Transition metals can change oxidation states, so can provide an intermediate for the reaction.
Haber process-- to make AMMONIA for fertilisers
- uses an iron catalyst, whichmeans we can reduce temp to, and save energy.
- N2+ 3H2>>> 2NH3
Contact Process--- to make SULFURIC ACID for detergents, adhesives, explosives and batteries.
- Uses vandium oxide, where vanadium is oxidised to 5+.
- 2SO2 + O2 >>> 2SO3
Hydrogenation of alkenes to saturate them--
- uses NICKEL
- C2H4 + H2>> C2H6
decomposition of hydrogen peroxide-- for oxygen
- uses manganese (IV)oxide with managanese is 4+ state.
- H2O2 >>> 2H2O +O2
Aqueous ions and hydroxide ions
- [Cu(H2O)6]2+ + 2OH- >>> Cu(OH)2 +6H2O
- Light blue solution to blue ppt
- [Co(H2O)6]2+ + 2OH- >>> Co(OH)2 + 6H2O
- pink solution to blue ppt (beige in oxygen)
- [Fe(H2O)6]2+ + 2OH- >>> Fe(OH)2 + 6H2O
- green solution to green ppt (red in oxygen)
- [Fe(H2O)6]3+ + 3OH- >>> Fe(OH)3 + 6H2O
- yellow solution to red ppt
Complex ions 4 definitions, common ligands
complex ion- a complex ion is a transition metal ion bonded to ligands by a coordinate bond.
ligand- a molecule which donates a lone pair to a central metal ion to make a coordinate bond.
coordinate bond- a bond where both electrons are donated by one molecule.
coordination number- this number represents the number of coordinate BONDS not the number of ligands.
common ligands e.g. water.
must have a lone pair.
charge must be shown outside the bracket
Shape of complex ion
shape of complex ions
- Most complex ions form a octahedral shape,
- with 6 bonds
- at 90 degrees.
- Has a square planar shape
bidentate and multidentate
e.g. ethane-1,2-diamine. Both nitrogens act as ligands, and make coordinate bonds.
The nitrogen has a lone pair, which it can donate to make a coordinate bond.
2 bidentate and 2 monodentate --- can also show cis trans isomerism.
e.g. EDTA u
- used in detergents- to bind with calcium and magneisum ions in water to reduce hardness
- in foods to remove metal ions that could oxidise the product
- added to blood samples to prevent clotting
- mercury poisoning cure.
Optical isomers are non-superimposable mirror images of each other.
- a complex with three molecules or ions or a bidentate ligand
- a complex with two bidentate molecules and two monodentate
- one hexdentate molecule
e.g. with 2 bidentate and 2 monodentate molecules
Anti cancer drug
- Two Cl groups, and two NH3 groups
it works by binding to DNA in cancer cells, and stopping division.
A precipitation reaction is when two soluble ions react to me an insoluble compound-- solid--ppt.
Transition metal ions react with aqueous NaOH to make coloured compounds.
Co2+ = pink solution
Co+ + OH- >>> Co(OH)2 = BLUE PPT
Fe2+ = green solution
Fe2+ + OH- >> Fe(OH)2 = GREEN PPT
Fe3+ = yellow solution
Fe3+ + OH_ >>> Fe(OH)3 = RED PPT
Ligand subsitution: Copper ions and ammonia
A ligand subsitution reaction is when the ligands in a complex solution are replaced by another.
Aqueous copper ions and ammonia
- Aqueous copper ions = BLUE solution
- Copper hydroxide = light blue ppt
- [Cu(NH3)4(H2O)2]2+= DEEP BLUE SOLUTION
[Cu(H2O)6]2+ + 4NH3 >>>> [Cu(NH3)4(H2O)2]2+ + 4H2O
Ligand subsitution: Copper/cobaltand HCL
Copper ions and concentrated hydrochloric acid
- aqueous copper ions= Pale blue solution
- copper chloride ions = green solution and then yellow.
It can be reversed by adding water.
The ligand complex formed is CuCl4(2-) from [Cu(H20)6]2+
Chloride ions are larger, so form a tetrahedral shape instead of octahedral.
Cobalt ions and hydrochloric acid
[Co(H2O)6]2+= a light pink solution
[CoCl4]2-= dark blue solution of
e.g. [Co(H2o)6]2+ + 4Cl- >>>> [CoCl4]2- + 6H2O
Haemoglobin has non-protein haem groups and at the centre of each haem is a Fe2+ ion, which can bind to oxygen, allowing the protein to carry the molecule.
Fe2+ has four coordinate bonds to the nitrogens in the haem structure, one to the protein globin, and one for a oxygen molecule.
The iron can gain and release O2 freely.
CO binds more strongly to the site on the Fe2+ molecules, and so stops oxygen from binding. This is a irreversible subsitution.
Will have a greater stability constant.
It is formed in the combustion in car engines, and also burning tobacco.
Kstab is the equilibrium constant for the formation of the complex ion in a solvent from its constituent ions.
When ions are added to another set of ions, a concentration equilibrium is set up.
We can write a type of stability constant for this, called Kstab.
Cu2+ + 6H2O >>> [Cu(H2O)6]2+
You put products over reactants (always miss out water).
- put the mols to the power
A large kstab indicates the position of the equilibrium is to the right, and favours the products.
Complex ions often have a very high stability constant, and are easily formed.
change in ox state x mols of oxidant = change in ox state x moles of reactant
MnO4- ions are colourless; Mn2+ ions are pink.
2Cu2+ + 4I- >> 2CuI + I2
MnO4(2-)+ 5e- +8H2O >>> Mn2+ + 4H2O
2S2O3(2-) + I2 >> 2I- + S4O6(2-)
Cr2O7(2-) + 6e- +14H+ >>>Cr3+ + 7H2O