Transition Metals
23.1 The general properties of transition metals: Haemoglobin, the red pigment in the blood that can
associate and dissociate with oxygen.
Transition metal: a metal that forms at least one stable • has a Fe2+ ion with a coordination number of 6
compound with a part full d orbital therefore not Sc or • 4 sites are taken by the tetradentate ligand haem
Zn as they have element with 3d0 and 3d10. • 1 site below the plane is a nitrogen atom acting as a
Transition metals move from Titainium to Copper, have ligand called globin
the a giant lattice structure with a high melting point, • The last site then allows oxygen to associate and
low reactivity this makes them very useful. dissociate as O2- isn’t a good ligand and so the dative
• has variable oxidation states bond is weak.
• Coloured • CO is a better ligand than oxygen and so the bond is
• Catalysts stronger and stops the association/dissociation
• Complex ions leading to suffocation.
Most of the elements have a full 4s orbital and so the • Anaemia caused by a shortage of haemoglobin and so
electrons add to the 3d orbitals. Apart from Copper and the body suffers from a lack of oxygen.
Chromium which has 4s1 electron and then the 3d
orbitals are filled. Isomers
Geometric isomerism, ligands differ in position in space
only in square planar and octahedral complexes. Ligands
23.2 Complex Formation and shape of complex ions: can be next to each other (z) or opposite (E). The geometric
isomers have different chemical properties .
Ligand: a ion or molecule with a lone pair of electrons
that can dative bond to the transition metal. Optical isomers, the geometric shapes are non-
Coordination number: the number that shows ho many superimposable mirror images of each other. Occurs when
ligands are bonded to the transition metal there’s 2+ bidentate ligands in a complex making the
• coordinate number of 6 will have an octahedral complex chiral. The optical isomers have the same chemical
shape properties.
• coordination number of 4 will have shape of Can be distinguished using plane polarised light, one
tetrahedral isomer rotates anti-clockwise the other will rotate
• Coordination number of 4 can also have a square clockwise.
planar shape
• Shape of complex depends on the size of the ligand, 23.3 Coloured ions:
larger ligands will have a tetrahedral shape as not
as many can fit in the same plane. Colour is seen because the compounds absorb energy that
corresponds to light frequencies in the visible light
Aqua ions: when a transition metal salt is dissolved in spectrum eg. A solution is purple means it absorbs red
water, the positively charged transition metal ion is and blue light from white light and shines through.
surrounded by water ligands which dative bond. Transition metals are coloured because,
• they have partially filled d orbitals so E- can move
Mulitdentate ligands (chelation): when a ligand has from one d-orbital to another
more than one atom with a lone pair of electrons and so • atoms of the same element have d orbitals of the same
can dative bond more than once. energy level, in a compound the the other atoms
Eg. means there’s slightly different energy levels.
• 1,2 diaminoethane (en), is a neutral ligand so • When electrons move to a higher energy level (the
doesn’t change the overall charge. excited state) they absorb energy from the visible
• Ethandioate ion C2O42- light spectrum equal to the difference between energy
• Benzene-1,2-diol, is a neutral ligand levels.
• EDTA4- , has 4 oxygen atoms and 2 nitrogen Energy difference = Planck constant x frequency
atoms with lone pairs that can dative bond • the colour will depend on the energy difference, this
changes with the metal’s oxidation state and the
chelates: complex ions with polydenntate ligands, can ligands that are attached.
remove d-block metal ions from solutions
Chelate effect, when a transition metal salt dissolves in Colorimetry, a light source detector measures the amount
water, the chelate will replace all the water ligands, this of light of a wavelength that passes through a coloured
leads to an increase in entropy so complexes with solution. The more concentrated the solution, the less
polydentate ligands are favoured over complexes with light will pass through. You draw a calibration curve for
monodentate ligands. concentration against transmittance / absorbance.
23.1 The general properties of transition metals: Haemoglobin, the red pigment in the blood that can
associate and dissociate with oxygen.
Transition metal: a metal that forms at least one stable • has a Fe2+ ion with a coordination number of 6
compound with a part full d orbital therefore not Sc or • 4 sites are taken by the tetradentate ligand haem
Zn as they have element with 3d0 and 3d10. • 1 site below the plane is a nitrogen atom acting as a
Transition metals move from Titainium to Copper, have ligand called globin
the a giant lattice structure with a high melting point, • The last site then allows oxygen to associate and
low reactivity this makes them very useful. dissociate as O2- isn’t a good ligand and so the dative
• has variable oxidation states bond is weak.
• Coloured • CO is a better ligand than oxygen and so the bond is
• Catalysts stronger and stops the association/dissociation
• Complex ions leading to suffocation.
Most of the elements have a full 4s orbital and so the • Anaemia caused by a shortage of haemoglobin and so
electrons add to the 3d orbitals. Apart from Copper and the body suffers from a lack of oxygen.
Chromium which has 4s1 electron and then the 3d
orbitals are filled. Isomers
Geometric isomerism, ligands differ in position in space
only in square planar and octahedral complexes. Ligands
23.2 Complex Formation and shape of complex ions: can be next to each other (z) or opposite (E). The geometric
isomers have different chemical properties .
Ligand: a ion or molecule with a lone pair of electrons
that can dative bond to the transition metal. Optical isomers, the geometric shapes are non-
Coordination number: the number that shows ho many superimposable mirror images of each other. Occurs when
ligands are bonded to the transition metal there’s 2+ bidentate ligands in a complex making the
• coordinate number of 6 will have an octahedral complex chiral. The optical isomers have the same chemical
shape properties.
• coordination number of 4 will have shape of Can be distinguished using plane polarised light, one
tetrahedral isomer rotates anti-clockwise the other will rotate
• Coordination number of 4 can also have a square clockwise.
planar shape
• Shape of complex depends on the size of the ligand, 23.3 Coloured ions:
larger ligands will have a tetrahedral shape as not
as many can fit in the same plane. Colour is seen because the compounds absorb energy that
corresponds to light frequencies in the visible light
Aqua ions: when a transition metal salt is dissolved in spectrum eg. A solution is purple means it absorbs red
water, the positively charged transition metal ion is and blue light from white light and shines through.
surrounded by water ligands which dative bond. Transition metals are coloured because,
• they have partially filled d orbitals so E- can move
Mulitdentate ligands (chelation): when a ligand has from one d-orbital to another
more than one atom with a lone pair of electrons and so • atoms of the same element have d orbitals of the same
can dative bond more than once. energy level, in a compound the the other atoms
Eg. means there’s slightly different energy levels.
• 1,2 diaminoethane (en), is a neutral ligand so • When electrons move to a higher energy level (the
doesn’t change the overall charge. excited state) they absorb energy from the visible
• Ethandioate ion C2O42- light spectrum equal to the difference between energy
• Benzene-1,2-diol, is a neutral ligand levels.
• EDTA4- , has 4 oxygen atoms and 2 nitrogen Energy difference = Planck constant x frequency
atoms with lone pairs that can dative bond • the colour will depend on the energy difference, this
changes with the metal’s oxidation state and the
chelates: complex ions with polydenntate ligands, can ligands that are attached.
remove d-block metal ions from solutions
Chelate effect, when a transition metal salt dissolves in Colorimetry, a light source detector measures the amount
water, the chelate will replace all the water ligands, this of light of a wavelength that passes through a coloured
leads to an increase in entropy so complexes with solution. The more concentrated the solution, the less
polydentate ligands are favoured over complexes with light will pass through. You draw a calibration curve for
monodentate ligands. concentration against transmittance / absorbance.
