Complexes

Question 1

What are complex ions?

Answer 1

Transition metal ions surrounded by ligands. The ligands donate electron pairs to the metal ion and form dative covalent bonds with it. Ligands are usually small (e.g. H2O) and contain a lone pair of electrons. The coordination number is the number of ligands attached to the central ion

Question 2

What does a complex with 6 ligands look like?

Answer 2

Octahedral shape, wedge arrows for bonds coming towards you and dashed arrows for bonds going away

Question 3

What does a complex with 4 ligands look like?

Answer 3

Either a tetrahedral shape or a square planar shape

Question 4

How do cis/trans isomer rules apply to complex ions?

Answer 4

As with double bonds, if two identical groups are on the same side, the ions is cis, if they are opposite each other, the ion is trans

Question 5

What happens if a ligand is substituted for another ligand of similar size?

Answer 5

The coordination number and shape don’t change

Question 6

What happens if a ligand is substituted for another different sized ligand?

Answer 6

Change of coordination number and therefore change of shape

Question 7

What is ligand substitution?

Answer 7

Ligands are swapped for other ligands, causing a colour change. Sometimes only some ligands are substituted

Question 8

Naming complex ions

Answer 8

Greek number suffix for number of ligands
Ligand name (aqua, ammine, cyano, fluoro, hydroxo)
Metal name
Metal oxidation number
Anion/cation