The Transition Metals

• Define a transition metal.

  Forms at least one stable ion with a d shell only partially full
• What are two elements that aren't transition metals but are in the d block? Why?

  • Scandium only forms Sc3+ (3d0)
  • Zinc only forms Zn2+ (3d10) in all its compounds
• What are the four main features of transition metals?

  • Variable oxidation states e.g Cu2+ and Cu+
  • Coloured compounds
  • Catalysis, used to speed up reactions without being chemically changed or used up themselves
  • Forms complex ions
• What is a ligand?

  A particle with a lone pair of electrons that bonds to metals by a co-ordinate bond
• What is a complex?

  Metal ion with coordinately bonded ligands
• What is a coordination number?

  Number of coordinate bonds from ligands to a metal ion
• What is a lewis base?

  A lone pair donor, ligand
• What is a lewis acid?

  A lone pair acceptor, metal ion
• What is the coordination number of a linear compound?

  2
• What metal forms linear complexes?

  Ag+
• What is the coordination number of a square planar complex?

  4
• What two metals form square planar complexes?

  Pt2+ and Ni2+
• What is the coordination number of a tetrahedral complex?

  4
• When do compounds form a tetrahedral complex?

  With larger ligands as they are too big to fit 6
• What is an example of a larger ligand?

  Cl-
• When do metals form an octahedral complex?

  With smaller ligands
• What are the examples of small ligands?

  H2O, NH3
• What is the angle of an octahedral complex?

  90
• What is the angle of a tetrahedral complex?

  109.5
• What is the angle of a square planar complex?

  90
• What is the angle of a linear complex?

  180
• What is a unidentate ligand?

  Ligands which form one coordinate bond to a metal ion
• What is a bidentate ligand?

  Ligands which form two coordinate bonds to a metal ion
• What is a multidentate ligand?

  Ligands which form more than two coordinate bonds to a metal ion
• What is the charge on EDTA?

  4-
• How many bonds does EDTA form?

  6
• What is the charge on 1,2-diaminoethane?

  0
• What is the charge on ethanedioate ion?

  2-
• How many bonds does 1,2-diaminoethane and ethanedioate form?

  6
• How many bonds does porphyrin form?

  4
• Why can oxygen bind to iron?

  Iron can form two more coordinate bonds
• In an octahedral complex, how many ligands are there and what is the coordination number with 3 1,2-diamino molecules?

  coordination number is 6 but only 3 ligands
• In what compounds does optical isomerism occur?

  in an octahedral complex with three bidentate ligands
• In what molecules can cis-trans isomerism arise?

  Octahedral and square planar complexes where there are two ligands of one type different to the other ligands
• What other compounds can form cis isomers that are also optical isomers?

  2 mono and 2 bi octahedrals
• What is a ligand substitution reaction?

  When one ligand is replaced by another ligand
• What happens to the coordination number in a ligand substitution reaction between similar sized ligands?

  Nothing
• If one ligand bonded to a metal ion is replaced by a ligand that is larger than it, what happens to the coordination number?

  Decreases~
• When is delta H negligible in a ligand substitution reaction?

  When the same number of similar bonds are being broken and formed
• When is there an increase in entropy in a ligand substitution reaction?

  When ligands are replaced by those that form more coordinate bonds, causing for example 4 aqueous particles to 7 aqueous particles