COLOURED IONS

Question 1

How does a transition metal ion become coloured? (1)

Answer 1

The colour is caused by the compounds absorbing energy that corresponds to light in the visible region of the spectrum.

Question 2

why are transition metal complexes coloured? (1)

Answer 2

because they have a part-filled d-orbital, it is therefore possible for electrons to move from one d-orbital to another. In an isolated transition metal all the d-orbitals are of the exact same energy but in a compound they have slightly different energies. When electrons move from one d-orbital to another of a higher energy level they often absorb energy in the visable region equal to the difference in energy between levels.

Question 3

what equation is used to determine the frequency of light compared to the energy difference? (1)

Answer 3

E=hv

Question 4

explain the equation to determine frequency of light compared to energy difference. (1)

Answer 4

E= energy
h=Planack’s constant
v=frequency

Question 5

what does the colour of a transition metal depend on? (1)

Answer 5

depends on the energy gap which in turn depends on the oxidation state of the metal and also on the ligands (and therefore the shape of the complex ion)

Question 6

Explain how a colorimeter works. (1)

Answer 6

uses a light source and a detector to measure the amount of light of a particular wavelength that passes through a coloured solution. The more concentrated the solution, the less light transmitted through the solution