Transition Metals

• What defines transition metals?

  Incomplete d-subshell and stable ions
• How do transition metals differ from d-block elements?

  Scandium and zinc do not have incomplete d-subshells
• Which elements are in the first transition series?

  Titanium to copper
• What is the Aufbau Principle in electron configuration?

  Electrons occupy the lowest energy subshells first
• Why is the 4s subshell filled before the 3d subshell?

  Because 4s overlaps with 3d subshell
• What is the abbreviation for the first five subshells?

  [Ar]
• What are the exceptions to the Aufbau Principle for transition metals?

  Chromium and copper promote electrons from 4s to 3d
• What are the general properties of transition metals?

  Variable oxidation states, complex ions, coloured compounds, catalysts
• What does it mean for transition elements to have variable oxidation states?

  They can form more than one positive ion
• How are oxidation states indicated for transition metals?

  Using Roman numerals
• What is a complex ion?

  A central metal atom with surrounding ligands
• What is the significance of ligands in complex ions?

  They surround and bond with the central metal ion
• What is the role of transition elements as catalysts?

  They change oxidation states during reactions
• What are the properties of transition elements?

  • Variable oxidation states
  • Form complex ions
  • Form coloured compounds
  • Behave as catalysts
• What is a ligand?

  A molecule or ion surrounding a central metal atom
• What is the coordination number?

  Number of coordinate bonds to the central metal atom
• What are monodentate ligands?

  Ligands that form one dative bond
• What are bidentate ligands?

  Ligands that form two dative bonds
• What are multidentate ligands?

  Ligands that form multiple dative bonds
• What is the coordination number for complexes with water and ammonia ligands?

  6
• What is the overall charge of a complex with cobalt(II) and neutral ligands?


  2+

  
• What is the overall charge of a complex with cobalt(II) and four chloride ligands?

  2−

  
• What is the overall charge of a complex with chromium(III) and six hydroxide ligands?

  3−

  
• What is ligand exchange?

  Replacement of one ligand in a complex
• What happens to the coordination number during ligand exchange?

  No change if ligands are similar in size
• What happens when ammonia is added to [Co(H₂O)₆]²⁺?

  It forms a pale yellow solution

  
• What is the result of complete ligand substitution in cobalt(II) complexes?

  Water ligands are replaced by ammonia ligands
• What happens to the stability of a complex ion when ligands are substituted?

  The stability can increase or decrease
• What can happen to ligands in a complex ion?

  They can be partially or entirely substituted
• How does the charge of a complex ion change?

  It can change or remain the same
• What happens to coordination number and geometry if ligands are similar in size?

  No changes occur in coordination number or geometry
• What occurs if ligands of different sizes are involved?

  Coordination number and geometry will change
• What is the color of the [Co(H₂O)₆]²⁺ complex ion?

  Pink

  
• What color solution forms when ammonia is added to [Co(H₂O)₆]²⁺?

  A pale yellow/straw colored solution forms

  
• What does the addition of ammonia to [Co(H₂O)₆]²⁺ indicate?

  Complete ligand substitution has occurred
• What is the reaction when ammonia is added to [Co(H₂O)₆]²⁺?

  [Co(H₂O)₆]²⁺ + 6NH₃ → [Co(NH₃)₆]²⁺ + 6H₂O

  
• What happens when excess concentrated ammonia is added to [Co(H₂O)₆]²⁺?

  A brown solution is formed

  
• Why does the cobalt(II) ion become unstable with ammonia?

  It readily gets oxidized to cobalt(III)
• What occurs upon dropwise addition of sodium hydroxide to [Co(H₂O)₆]²⁺?

  A blue precipitate is formed

  
• What does the blue precipitate indicate in the reaction with sodium hydroxide?

  Partial ligand substitution has occurred