Transition metals

• What are transition metals characterized by?


  Partially filled d-orbital
• How do transition metals form positive ions?

  By losing s-orbital electrons first
• What are the common physical properties of transition metals?

  • Similar atomic radius
  • High densities
  • High melting points
  • High boiling points
• What are the special chemical properties of transition metals?

  • Form complexes
  • Form coloured ions
  • Variable oxidation states
  • Act as good catalysts
• What is a complex in chemistry?

  A central metal ion surrounded by ligands
• How can complexes be represented in formulas?

  Using square brackets
• What are ligands?

  Molecules or ions with a lone electron pair
• What are common ligands in transition metal complexes?

  • Cl^-
  • H₂O
  • NH₃
• What is the coordination number in a complex?

  Number of coordinate bonds around the metal ion
• What is the coordination number of silver complexes?

  2
• What is the coordination number of platinum complexes?

  4
• What happens during a ligand substitution reaction?

  Ligands are exchanged without changing coordination number
• Which ligands can be exchanged without changing coordination number?

  NH₃ and H₂O
• What is the result of ligand substitution with Cl^-?

  Change in coordination number occurs
• What is the coordination number of complexes with only Cl^- ligands?

  Four
• What are bidentate ligands?

  • Form two coordinate bonds
  • Have two lone electron pairs
  • Can replace two unidentate ligands
• What are common bidentate ligands?

  • Ethanedioate ions
  • Ethane-1,2-diamine
• What are multidentate ligands?

  • Form up to six coordinate bonds
  • Have multiple lone electron pairs
  • Example: EDTA
• What is the role of haem in the body?

  Transport oxygen
• Why is carbon monoxide toxic?

  It replaces oxygen in haem complexes
• What is the chelate effect?

  • Positive entropy change is favorable
  • More moles on the right than left
  • Substituting unidentate with bidentate or multidentate ligands
• What is the enthalpy change for ligand substitution reactions?

  Very small, near zero
• What shape do octahedral complexes form?

  Octahedral shape
• What is the bond angle in octahedral complexes?

  90 degrees
• What is cis-trans isomerism in octahedral complexes?

  • Ligands can be next to or opposite each other
  • Trans has same ligands opposite
  • Cis has same ligands next to each other
• What is optical isomerism in octahedral complexes?

  • Occurs with bidentate ligands
  • Isomers are mirror images
• What shape do tetrahedral complexes form?

  Tetrahedral shape
• What is the bond angle in tetrahedral complexes?

  109.5 degrees
• What shape do square planar complexes form?

  Square planar shape
• What is the bond angle in square planar complexes?

  90 degrees
• What is the shape of silver complexes?

  Linear shape
• What is the bond angle in linear complexes?

  180 degrees
• What is cisplatin used for?

  Cancer therapy drug
• Why is only one isomer of cisplatin effective?

  Only one fits the chiral cells
• What are the side effects of cisplatin?

  Hair loss and other serious effects
• What factors affect the color of transition metal ions?

  • Coordination number
  • Type of ligand
  • Oxidation state
• How does color arise in transition metal complexes?

  From absorbed and reflected light wavelengths
• What happens to electrons in the d-orbital when energy is given?

  They move to a higher energy state
• What is colorimetry used for?

  Determine concentration of coloured ions
• What is the process of colorimetry?

  • Measure absorbance of known concentrations
  • Produce a calibration graph
  • Use graph to find unknown concentration