Formation of coloured ions

Question 1

What happens when ligands bond to the ions?

Answer 1

Some orbitals are given more energy than others

Question 2

What orbitals do the electrons occupy?

Answer 2

Lower orbitals

Question 3

What do the electrons need to jump up to the higher orbitals?

Answer 3

They need energy equal to the energy gap

Question 4

Where do electrons get the energy from to jump up energy state?

Answer 4

From visible light

Question 5

What equation is used to calculate the light energy absorbed by the electrons?

Answer 5

∆E = hv = hc/λ

Question 6

What is the unit for ∆E?

Answer 6

J

Question 7

What is h?

Answer 7

Planck’s constant

Question 8

What is v?

Answer 8

Frequency of light absorbed

Question 9

What is c?

Answer 9

the speed of light

Question 10

What is the value for the speed of light?

Answer 10

3.00 x 10⁸ m s⁻¹

Question 11

what is λ?

Answer 11

Wavelength of light

Question 12

What is the unit for λ?

Answer 12

m

Question 13

What are the units for v?

Answer 13

Hertz

Question 14

what is the value for Planck’s constant?

Answer 14

6.63 x 10-³⁴ Js

Question 15

Why do you see colours of compounds?

Answer 15

some frequencies are absorbed as electrons jump up to the higher orbitals and the light frequencies not absorbed are reflected and thats the colour you see

Question 16

Why does you see a colourless solution sometimes?

Answer 16

If there are no 3d electrons or the 3d sub-level is formed
no electrons will jump, no light absorbed
all light reflected

Question 17

What three things can you use to identify transition metal ions?

Answer 17

Changes in oxidation state
Changes in co-ordination number
Changes in ligand

Question 18

How is spectroscopy used to determine the concentration of a solution?

Answer 18

• white light is shone through a filter which is chosen to only let the colour of light through that is absorbed by the sample
• Then light passes through the sample to a colorimeter which shows how much light was absorbed by the sample
• plot a calibration graph

Question 19

The more concentrated a coloured solution…

Answer 19

…the more light it will absorb

Question 20

How do you calculate an unknown concentration of a solution?

Answer 20

• Produce a calibration curve of the known concentration values
• Concentration on the x axis
• Relative absorbance on the y axis
• Then use the relative absorbance to look at the concentration of the unknown sample