transition metals

• ligands must have a lone pair and form co-ordinate bonds with transition metal ions
• the co-ordination number is the number of ligands around a transition metal ion
• the size of each ligand determins the coordination number
• ligands of nickel, palladium and platinum tend to be square planar
• Why are transition metals coloured?

  Transition elements have 3d orbitals with the same energy level however when ligands form coordinate bonds with a metal ion, the electron repulsion causes the 3d orbitals to split into lower and higher energy levels.The energy required to cause an electron to jump from a 3d orbital to higher 3d orbital corresponds to a certain wavelength of visible light.
• vanadium pentoxide is used as a catalyst in the contact proccess
• Cis-platin is a very effective anti-cancer drug
• When d-block elements form ions, the 4s electrons are lost first
• Tollens reagent has a linear shape
• Coloured ions can split d orbitals
• How are coloured ions formed?

  Visible light is absorbed by the electrons in the split 3d orbital allowing it to migrate up to a higher energy level (absorption)
• The gap between the split 3d orbitals determines the colour we see
• What is plank’s constant?

  Change in energy = planks constant x frequency
• Iron 3+ is yellow in solution
• Iron 2+ is green in solution
• Cu 2+ is blue in solution
• Al 3+ is colourless
• heterogeneous catalysts are in a different phase to the reactants