[24.2] the formation of shapes of complex ions

Question 1

what is a ligand?

Answer 1

atom / anion / molecule with a lone pair that forms dative covalent bonds to metal ions

Question 2

what is a complex?

Answer 2

metal ion with ligands datively bonded to it

Question 3

what is the co-ordination number?

Answer 3

number of dative covalent bonds from ligand(s) to metal ions

Question 4

how are ligands lewis bases?

Answer 4

both are lone pair donors

Question 5

what is a monodentate ligand?

Answer 5

a ligand that contains one pair of electrons to a central metal ion

eg. H₂O:, :NH₃, :OH⁻, :CN⁻, : Cl⁻

Question 6

what are bidentate ligands?

Answer 6

ligands which donate two lone pairs of electrons to the central metal ion, forming two coordinate bonds

eg. 1,2-diaminoethane (en), ethanedioate (oxalate ion)

Question 7

what are multidentate ligands?

Answer 7

ligands which form several co-ordinate bonds eg. haemoglobin

Question 8

uses of some complexes

Answer 8

• V₂O₅ - catalyst in contact process
• Mn²⁺ - autocatalyst in MnO₄ / C₂O₄²⁻ titrations
• haemoglobin - contains Fe²⁺, allows oxygen to bind and be carried to where it is needed
• [Pt(NH₃)₂Cl₂] - cis platin, anti-cancer drug
• [Ag(NH₃)₂]⁺ - used in tollen’s reagent to distinguish aldehydes and ketones

Question 9

where do linear, tetrahedraal, square planar and octahedral complexes occur?

Answer 9

• linear = Ag⁺ complexes
• tetrahedral = large ligands (eg. Cl⁻)
• square planar = Pt²⁺ complexes
• octahedral = most common