a) How can an element be classified as a transition metal, considering only electronic arrangement? (1 mark) b) In terms of electrons, why is aqueous copper(II) sulphate solution red? (3 marks) c) EDTA is a bidentate ligand. What is a bidentate ligand?(2)

a) Partially filled/incomplete d shell.
b) Light is absorbed by an electron, exciting it and is promoted to a higher energy d orbital. The colour seen is the complimentary colour of that absorbed (in this case blue light is absorbed).
c)A bidentate ligand are lewis bases that donate 2 electrons to the central metal atom. They often are chelating and interact with the metal in two positions.