Transition metals

• 1. block elements


  The elements in the middle of the periodic table
• Transition metals


  • Scandium to zinc
• Transition metal


  A d-block element that can form at least one stable ion with a partially filled or incomplete d-subshell
• Only 8 of the period 4 d-block elements are transition metals
• Filling of electron orbitals in transition metals

  1. Singly first, then doubly

  2. Atoms want to be in lowest energy state
• Chromium and copper have unusual electron configurations
• Scandium


  Not a transition metal as its stable ion Sc3+ has a fully filled d-subshell
• Zinc


  Not a transition metal as its stable ion Zn2+ has a fully filled d-subshell
• Ionization of iron

  1. Loses 2 electrons from 4s, then 1 from 3d to form Fe3+

  2. Fe3+ has a partially filled 3d-subshell
• Transition metals have variable oxidation states
• Transition metals


  • Form colored ions and solutions
  • Are good catalysts
• The closeness in energy of the 4s and 3d orbitals gives transition metals their unique properties
• Transition metals

  Have variable oxidation states
• Transition metals have variable oxidation states because the electrons sit in the 4s and 3d orbitals which are close in energy
• Transition metal ions

  Can form a variety of different ions
• Examples of transition metals

  • Vanadium
  • Chromium
  • Manganese
  • Iron
  • Cobalt
  • Nickel
  • Copper
  • Zinc
• Zinc and scandium are d-block elements but not transition elements
• Chromium 3+

  Greeny violet
• Iron 2+


  Pale green
• Cobalt 2+


  Fuchsia pink
• Complex ion


  A central transition metal ion surrounded by ligands, bonded by dative covalent or coordinate bonds
• Complex ions


  • Have a central metal ion
  • Surrounded by ligands
  • Bonded by dative covalent or coordinate bonds
• Monodentate ligand


  Ligand with one lone pair of electrons to donate
• Examples of monodentate ligands


  • Water
  • Ammonia
  • Chloride ion
• Bidentate ligand


  Ligand with two lone pairs of electrons to donate
• Examples of bidentate ligands

  • Ethylenediamine
  • Oxalate
• Multidentate ligand

  Ligand with more than one coordinate bond
• Examples of multidentate ligands

  • Heme
  • EDTA
• Coordination number


  The number of coordinate bonds in a complex, not the number of ligands
• Ligand size and coordination number

  • Smaller ligands allow more to fit around the central metal (up to 6)
  • Larger ligands limit the number that can fit around the central metal (down to 3)
• Octahedral complex


  Complex with 6 ligands around the central metal, bond angles of 90 degrees
• Tetrahedral complex


  Complex with 4 ligands around the central metal, bond angles of 109.5 degrees
• Square planar complex


  Complex with 4 ligands in a flat arrangement around the central metal, bond angles of 90 degrees
• Linear complex


  Complex with 2 ligands in a straight line around the central metal, bond angle of 180 degrees
• The overall charge of a complex ion is equal to the total oxidation state of the central metal minus the total oxidation state of the ligands
• Ligand


  The type and number of ligands surrounding a metal ion determines the complex and its overall charge
• Total oxidation state of a complex


  The same as the total oxidation state of the metal
• Determining the oxidation state of the metal in a complex

  Total oxidation state of the complex - Total oxidation state of the ligands = Oxidation state of the metal
• Hemoglobin


  Protein that transports oxygen, contains the ligand heme
• Heme


  • A multi-dentate ligand that bonds to the iron in hemoglobin