Why transition metals ion complexes have diff colour? Transition Metal – Colour Complexes Colour you see is BLUE – Blue reflected/transmitted to your eyes - Red/orange absorbed (complementary colour) Colour you see is Yellow – Yellow reflected/transmitted to your eyes - Violet absorbed (complementary colour) complementary colour Blue transmitted Wave length - absorbed Wave length - absorbed Visible light Visible light Yellow transmitted absorbed
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IB Chemistry on Absorption Spectrum and Line Emission/Absorption Spectrum
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Why transition metals ion complexes have diff colour?
Transition Metal – Colour Complexes
Colour you see is BLUE – Blue reflected/transmitted to your eyes - Red/orange absorbed (complementary colour)
Colour you see is Yellow – Yellow reflected/transmitted to your eyes - Violet absorbed (complementary colour)
Transition Metal – Colour Complexes Colour- Splitting 3d orbital by ligand
Strong ligand (higher charge density) ↓
Greater splitting - ↑∆E - Diff colour
Weak ligand (Low charge density) ↓
Smaller splitting - ↓∆ E - Diff colour
Spectrochemical series – Weak ligand → Strong Ligand
WEAK ligand – small splitting
3d orbital (Unequal energy)
∆E ∆E
STRONG ligand – greater splitting
3d orbital (Unequal energy)
Very Strong ligand ↓
Greater splitting - ↑∆E- Diff colour
∆E
Cu(H2O)62+ 3d9 Blue
STRONGEST ligand – greatest splitting
[Cu(NH3)4]2+ [Cu(H2O)6]
2+
- Lower energy absorbed
- Red wavelength absorb to excite electron
[Cu(CI)4]2-
Cu(CI4)2- 3d9 Green Cu(NH3)42+ 3d9 Violet
Nuclear charge - +5
↓
Strong ESF atrraction bet –ve ligand
↓
Greatest splitting ∆E
↓
Highest energy wavelength absorb
Nuclear charge - +3
↓
Strong ESF atrraction bet –ve ligand
↓
Greater splitting ∆E
↓
Higher energy wavelength absorb
Mn(H2O)62+ +2 PINK
Nuclear charge - +2
↓
Weak ESF atrraction bet –ve ligand
↓
Smaller splitting ∆E
↓
Low energy wavelength absorb
- Higher energy absorbed
- Blue wavelength absorb to excite electron
- Highest energy absorbed
- Violet wavelength absorb to excite electron
Transition Metal – Colour Complexes Colour- Splitting 3d orbital by ligand
High nuclear charge / charge density ↓
Greater splitting - ↑∆E - Diff colour
Low nuclear charge /charge density ↓
Smaller splitting - ↓∆ E - Diff colour
Nuclear charge on metal ion
Low nuclear charge – small splitting
3d orbital (Unequal energy)
∆E ∆E
High nuclear charge – greater splitting
3d orbital (Unequal energy)
Highest nuclear charge/charge density ↓
Greatest splitting - ↑∆E- Diff colour
∆E
Fe(H2O)63+ +3 YELLOW
HIGHEST nuclear charge – greatest splitting
Fe(H2O)63+
- Lower energy absorbed
- Green wavelength absorb to excite electron
V(H2O)65+ +5 YELLOW/GREEN
Mn(H2O)62+ V(H2O)6
5+
Oxidation number - +3
↓
Strong ESF atrraction bet –ve ligand
↓
Greater splitting ∆E
↓
Higher energy wavelength absorb
Oxidation number - +2
↓
Weak ESF atrraction bet –ve ligand
↓
Smaller splitting ∆E
↓
Low energy wavelength absorb
Transition Metal – Colour Complexes Colour- Splitting 3d orbital by ligand
Higher oxidation number/charge density ↓
Greater splitting - ↑∆E - Diff colour
Lower ESF attraction – small splitting
3d orbital (Unequal energy)
∆E ∆E
STRONG ligand – greater splitting
3d orbital (Unequal energy)
∆E
Fe(H2O)63+ +3 Yellow
- Lower energy absorbed
- Red wavelength absorb to excite electron
Fe(H2O)62+ +2 Green
Oxidation number on metal ion
Low oxidation number /charge density ↓
Smaller splitting - ↓∆ E - Diff colour
Fe(H2O)62+
- Higher energy absorbed
- Blue wavelength absorb to excite electron
Fe(H2O)63+
V(H2O)65+ +5 YELLOW/GREEN
Highest oxidation number/charge density ↓
Greatest splitting - ↑∆E- Diff colour
HIGHEST nuclear charge – greatest splitting
- Highest energy absorbed
- Violet wavelength absorbed to excite electron
Nuclear charge - +5
↓
Strongest ESF atrraction bet –ve ligand
↓
Greatest splitting ∆E
↓
Highest energy wavelength absorb
V(H2O)65+
Electromagnetic Spectrum
Electromagnetic spectrum ranges from Radiowaves to Gamma waves. - Form of energy - Shorter wavelength -> Higher frequency -> Higher energy - Longer wavelength -> Lower frequency -> Lower energy
Electromagnetic radiation • Travel at speed of light, c = fλ -> 3.0 x 108 m/s • Light Particle – photon have energy given by -> E = hf • Energy photon - proportional to frequency
Inverse relationship between- λ and f Wavelength, λ - long
Frequency, f - low
Wavelength, λ - short Frequency, f - high
Plank constant • proportionality constant bet energy and freq
Excellent video wave propagation Click here to view.
Electromagnetic radiation • Moving charges/particles through space • Oscillating wave like property of electric and magnetic field • Electric and magnetic field oscillate perpendicular to each other and perpendicular to direction of wave propagation.
Electromagnetic wave propagation
Wave – wavelength and frequency - travel at speed of light