transition metals

• Oxide with the highest melting point is MgO
• The oxides of period 3 elements display a gradual increase in acidity along the period when dissolved in water.
• Sodium hydroxide is a strong base. (pH 12-14)
• A ligand is a molecule which forms a dative bond with a transition metal
• An ion with ligands attached to it is called a complex ion
• Properties of ions of transition metals that aren't shared by other metals:

  1)Multiple oxidation states 2)Form colored ions in solution 3)Great catalysts in chemical reactions 4)Form complexes with ligands
• A ligand that can form two bonds is called bidentate
• • A ligand that can form multiple bonds is called multidentate.
• Multidentate ligands will almost always replace monodentate ligands at a metal centre. This is called the chelate effect.
• • The chelate effect is largely an entropic effect.
  • When you substitute a multidentate ligand for a monodentate ligand, you increase the number of moles of molecules in the products of the reaction.
  • This leads to a large increase in entropy and this brings the Gibbs free energy below zero for the change.
• Denticity describes the number of dative bonds that can be formed with a transition metal by one ligand.
• The colour of transition metals ions depends on their ligands and their geometries.
• Electrons will occupy the lower energy orbitals first. This is called the ground electronic state of the ion.
• • If an electron absorbs energy equal to the energy gap, it can move to occupy the higher energy orbitals. This is called an excited electronic state.
• • When a transition metal ion is in light, it will absorb the frequencies which correspond to the d sub-shell energy gap.
  • The rest of the frequencies will be reflected.
  • You only see the reflected light.
• 1{Cu(Cl)4}2+ is yellow 2{Co(H2O)6}2+ is pink 3{Co(NH3)6}2+ is straw coloured