Source: https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/2-4-6-colours-of-ions

[Revision notes](https://senecalearning.com/en-gb/revision-notes.md) › [International A Level](https://senecalearning.com/en-gb/revision-notes/international-a-level.md) › [Chemistry](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry.md) › [Cambridge International](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international.md) › Colours of Ions

# Colours of Ions

Chemistry: Cambridge International A Level, topic 2.4.6

## d Sub-Shell Splitting

The colour of transition metals ions depends on their ligands and their geometries.

### Splitting

![Splitting](https://image-v2.cdn.app.senecalearning.com/2018-07/e1334662-ea0e-4882-aa04-cc3f14f719cd/d%20sub-shell%20splitting%20(1).jpg)

- Without ligands, all of the d orbitals have the same energy.
 - In the presence of ligands, the orbitals will split. Some of them gain energy, and some of them lose energy. 
 - This is shown in the following diagram. 
 - The difference in energy of the upper level and the lower level is given the symbol ΔE.

### Light absorption

![Light absorption](https://image-v2.cdn.app.senecalearning.com/courseImages/physics/3.1.2%20Internal%20reflection/light-567758_640-min.jpg)

- Electrons will occupy the lower energy orbitals first. This is called the ground electronic state of the ion.
 - If an electron absorbs energy equal to the energy gap, it can move to occupy the higher energy orbitals. This is called an excited electronic state.
 - Electrons will absorb frequencies of light that contain enough energy to jump the energy gap.
 - This is shown pictorially on the next slide.

### Calculating the energy gap

![Calculating the energy gap](https://image-v2.cdn.app.senecalearning.com/courseImages/physics/1.4.2%20Equilibrium/calculator-983900_640-min.jpg)

- You can calculate the energy gap from the wavelength of absorbed light by using the following formula:
 - $$\Delta E = h\nu = \frac{hc}{\lambda}$$ 
 - ν is the frequency of light in hertz, h is planck’s constant (which will be given if you need it), c is the speed of light in ms-1 and λ is the wavelength of the light in metres.
- The energy gap depends on the metal ion, it's oxidation state, it's ligands, and also it's coordination number.

## Colours of Transition Metal Ions

The colour of a transition metal ion depends on the colour of the light it absorbs.

### Absorption process

![Absorption process](https://image-v2.cdn.app.senecalearning.com/2018-04/e01928fd-51c9-4a0f-8296-ae1a7ae063e5/shutterstock_684708202.jpg)

- When a transition metal ion is in light, it will absorb the frequencies which correspond to the d sub-shell energy gap.
 - The rest of the frequencies will be reflected. 
 - You only see the reflected light.

### Absorption example

![Absorption example](https://image-v2.cdn.app.senecalearning.com/2018-08/db05b86d-9b5a-48a9-8828-cba4d6f7b9e9/light-dispersion-prism-.jpg)

- Suppose you have a metal complex which absorbs red light.
 - The red light is removed from the light you can see.
  - You see the rest of the colours in the spectrum.
  - So the complex appears blue.
- Metal ions that absorb red light do NOT appear red, because there’s no red light for you to see.

### Identifying metal ions

![Identifying metal ions](https://image-v2.cdn.app.senecalearning.com/2018-09/bddc7f67-9ad5-4b9f-9479-f1e893ab9696/clue.png)

- Every transition metal ion will be a different colour with different ligands.
 - But we can identify all the hexaaqua ions (the ones with six water ligands), and we also know the colours of some other specific ones.
 - The ones you need to know are on the next slide.

### Metal ion colours

![Metal ion colours](https://image-v2.cdn.app.senecalearning.com/2018-07/10bd9b04-41cf-429a-8926-b642b2af8bd9/Ion%20Colours.jpg)

### Iron(III) in solution

![Iron(III) in solution](https://image-v2.cdn.app.senecalearning.com/courseImages/chemistry/1.1.1-Mixtures%20and%20compounds/Iron-min.jpg)

- On the previous slide, we gave you the colours of certain ions. While these colours are true, you might not always observe them. 
 - Iron(III) in solution usually appears yellow or orange if its concentrated.
 - This is because hexaaqua iron(III) is quite acidic, and will lose protons to become Fe(H2O)5(OH-) (and this is yellow).
 - If you’re asked what colour hexaaqua iron(III) is, you should say purple. Just be aware that if it's in solution, you’ll have a yellow solution.
 - We’ll talk about the acidic properties in a later module.

## Spectroscopy

You can use the colour of ions to find their concentrations. This uses a technique called spectroscopy.

### Principles of spectroscopy

![Principles of spectroscopy](https://image-v2.cdn.app.senecalearning.com/2018-08/59e3357e-e9bc-402c-9e9d-5e66dc56d227/red-blue-filter-.jpg)

- You can shine white light through a coloured filter to remove everything but that colour of light.
 - You can then let this light fall on a sample of a transition metal solution.
 - The more light it absorbs, the higher the concentration of the solution.
 - We can compare the amount of light absorbed to a calibration curve (this is explained on the next slide).

### Calibration curves

![Calibration curves](https://image-v2.cdn.app.senecalearning.com/2018-07/47bba387-069a-405c-ace5-789b85298004/Calibration%20curve.jpg)

- When doing spectroscopy, we can’t calculate the concentration of a sample without comparing it to known concentrations.
 - We first measure the absorbances of solutions whose concentrations we know. Then we plot these on a graph.
 - This graph is called a calibration curve. An example is on the next slide.
- We then use the absorbance of the unknown sample to work out from the graph what its concentration is.

![](https://image-v2.cdn.app.senecalearning.com/2018-07/47bba387-069a-405c-ace5-789b85298004/Calibration%20curve.jpg)

## Test yourself on Colours of Ions

- What do you need to form a calibration curve?

[Practise this topic for free](https://app.senecalearning.com/classroom/course/2eb3e96b-13a1-48db-b631-5d0098e3ed27/section/d85b0ebf-1ada-4b7d-a1b3-419df1579e37/session)

- Previous topic: [2.4.5 Ligands](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/2-4-5-ligands.md)
- Next topic: [2.4.7 Stereoisomerism of Complex Ions](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/2-4-7-stereoisomerism-of-complex-ions.md)

## Chemistry: Cambridge International A Level contents

### 1 Physical Chemistry
- 1.1 Atoms, Molecules & Stoichiometry
  - [1.1.1 Relative Masses](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-1-1-relative-masses.md)
  - [1.1.2 The Mole](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-1-2-the-mole.md)
  - [1.1.3 Mass Spectrometry](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-1-3-mass-spectrometry.md)
  - [1.1.4 Empirical & Molecular Formulae](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-1-4-empirical-and-molecular-formulae.md)
  - [1.1.5 Balanced Equations](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-1-5-balanced-equations.md)
  - [1.1.6 Molar Volume](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-1-6-molar-volume.md)
  - [1.1.7 End of Topic Test - Amount of Substance](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-1-7-end-of-topic-test-amount-of-substance.md)
- 1.2 Atomic Structure
  - [1.2.1 Fundamental Particles](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-2-1-fundamental-particles.md)
  - [1.2.2 Isotopes & Mass Number](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-2-2-isotopes-and-mass-number.md)
  - [1.2.3 Electron Shells, Sub-Shells & Orbitals](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-2-3-electron-shells-sub-shells-and-orbitals.md)
  - [1.2.4 Electron Configuration](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-2-4-electron-configuration.md)
  - [1.2.5 Ionisation Energy](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-2-5-ionisation-energy.md)
  - [1.2.6 Factors Affecting Ionisation Energies](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-2-6-factors-affecting-ionisation-energies.md)
  - [1.2.7 Trends of Ionisation](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-2-7-trends-of-ionisation.md)
  - [1.2.8 Specific Impacts on Ionisation Energies](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-2-8-specific-impacts-on-ionisation-energies.md)
  - [1.2.9 Electron Affinity](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-2-9-electron-affinity.md)
  - [1.2.10 End of Topic Test - Atomic Structure](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-2-10-end-of-topic-test-atomic-structure.md)
  - [1.2.11 A-A* (AO2/3) - Atomic Structure](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-2-11-a-a-ao23-atomic-structure.md)
- 1.3 Chemical Bonding
  - [1.3.1 Ionic Bonding](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-3-1-ionic-bonding.md)
  - [1.3.2 Covalent & Dative Bonding](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-3-2-covalent-and-dative-bonding.md)
  - [1.3.3 Shapes of Molecules](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-3-3-shapes-of-molecules.md)
  - [1.3.4 Intermolecular Forces](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-3-4-intermolecular-forces.md)
  - [1.3.5 Intermolecular Forces 2](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-3-5-intermolecular-forces-2.md)
  - [1.3.6 Electronegativity](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-3-6-electronegativity.md)
  - [1.3.7 Bond Length, Bond Energy, & Bond Polarity](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-3-7-bond-length-bond-energy-and-bond-polarity.md)
  - [1.3.8 Metallic Bonding](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-3-8-metallic-bonding.md)
  - [1.3.9 Physical Properties](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-3-9-physical-properties.md)
  - [1.3.10 End of Topic Test - Bonding](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-3-10-end-of-topic-test-bonding.md)
  - [1.3.11 A-A* (AO2/3) - Bonding](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-3-11-a-a-ao23-bonding.md)
- 1.4 States of Matter
  - [1.4.1 Simple Covalent Molecules](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-4-1-simple-covalent-molecules.md)
  - [1.4.2 The Ideal Gas Equation](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-4-2-the-ideal-gas-equation.md)
  - [1.4.3 States of Matter](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-4-3-states-of-matter.md)
  - [1.4.4 Particle Diagrams](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-4-4-particle-diagrams.md)
  - [1.4.5 The Liquid State](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-4-5-the-liquid-state.md)
  - [1.4.6 Giant Ionic Lattices](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-4-6-giant-ionic-lattices.md)
  - [1.4.7 Giant Metallic Lattices](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-4-7-giant-metallic-lattices.md)
  - [1.4.8 Giant Covalent Structures](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-4-8-giant-covalent-structures.md)
  - [1.4.9 Graphene & Fullerene](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-4-9-graphene-and-fullerene.md)
  - [1.4.10 Recycling](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-4-10-recycling.md)
- 1.5 Chemical Energetics
  - [1.5.1 Calorimetry](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-5-1-calorimetry.md)
  - [1.5.2 Bond Enthalpies](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-5-2-bond-enthalpies.md)
  - [1.5.3 Enthalpy Changes](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-5-3-enthalpy-changes.md)
  - [1.5.4 Hess' Law](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-5-4-hess-law.md)
  - [1.5.5 Born-Haber Cycles](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-5-5-born-haber-cycles.md)
  - [1.5.6 Born-Haber Cycle Calculations](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-5-6-born-haber-cycle-calculations.md)
  - [1.5.7 Entropy](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-5-7-entropy.md)
  - [1.5.8 Free Energy](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-5-8-free-energy.md)
  - [1.5.9 End of Topic Test - Energetics](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-5-9-end-of-topic-test-energetics.md)
- 1.6 Electrochemistry
  - [1.6.1 Electrochemical Cells](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-6-1-electrochemical-cells.md)
  - [1.6.2 Electrochemical Series](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-6-2-electrochemical-series.md)
  - [1.6.3 Commercial Application](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-6-3-commercial-application.md)
  - [1.6.4 Nernst Equation](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-6-4-nernst-equation.md)
  - [1.6.5 Redox](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-6-5-redox.md)
- 1.7 Equilibria
  - [1.7.1 Dynamic Equilibrium & Le Chatelier](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-7-1-dynamic-equilibrium-and-le-chatelier.md)
  - [1.7.2 Kc](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-7-2-kc.md)
  - [1.7.3 Kp](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-7-3-kp.md)
  - [1.7.4 pH](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-7-4-ph.md)
  - [1.7.5 The Ionic Product of Water](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-7-5-the-ionic-product-of-water.md)
  - [1.7.6 Weak Acids & Bases](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-7-6-weak-acids-and-bases.md)
  - [1.7.7 Introduction to Solubility Equilibria](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-7-7-introduction-to-solubility-equilibria.md)
  - [1.7.8 Solubility Equilibria Calculations](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-7-8-solubility-equilibria-calculations.md)
  - [1.7.9 Free Energy of Dissolution](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-7-9-free-energy-of-dissolution.md)
  - [1.7.10 pH and Solubility](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-7-10-ph-and-solubility.md)
  - [1.7.11 Common-Ion Effect](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-7-11-common-ion-effect.md)
  - [1.7.12 End of Topic Test - Kp & Electrochemistry](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-7-12-end-of-topic-test-kp-and-electrochemistry.md)
  - [1.7.13 A-A* (AO2/3) - Electrochemical Cells](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-7-13-a-a-ao23-electrochemical-cells.md)
- 1.8 Partition Coefficient
  - [1.8.1 Kpc](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-8-1-kpc.md)
- 1.9 Reaction Kinetics
  - [1.9.1 Collision Theory](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-9-1-collision-theory.md)
  - [1.9.2 Orders, Rate Constants & Equations](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-9-2-orders-rate-constants-and-equations.md)
  - [1.9.3 Rate Graphs](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-9-3-rate-graphs.md)
  - [1.9.4 Rate Determining Step](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-9-4-rate-determining-step.md)
  - [1.9.5 Maxwell-Boltzmann Distribution](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-9-5-maxwell-boltzmann-distribution.md)
  - [1.9.6 Catalysts](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-9-6-catalysts.md)
  - [1.9.7 Homogeneous Catalysts](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-9-7-homogeneous-catalysts.md)
  - [1.9.8 Heterogeneous Catalysts](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-9-8-heterogeneous-catalysts.md)
  - [1.9.9 End of Topic Test - Kinetics](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-9-9-end-of-topic-test-kinetics.md)
  - [1.9.10 End of Topic Test - Rate Equations](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-9-10-end-of-topic-test-rate-equations.md)
  - [1.9.11 A-A* (AO2/3) - Rate Equations](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/1-9-11-a-a-ao23-rate-equations.md)

### 2 Inorganic Chemistry
- 2.1 The Periodic Table
  - [2.1.1 The Periodic Table](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/2-1-1-the-periodic-table.md)
  - [2.1.2 Trends in the Periodic Table](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/2-1-2-trends-in-the-periodic-table.md)
  - [2.1.3 End of Topic Test - Periodicity & Trends](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/2-1-3-end-of-topic-test-periodicity-and-trends.md)
  - [2.1.4 Ceramics](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/2-1-4-ceramics.md)
  - [2.1.5 Period 3 Elements & Oxides](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/2-1-5-period-3-elements-and-oxides.md)
  - [2.1.6 Period 3 Oxides](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/2-1-6-period-3-oxides.md)
  - [2.1.7 End of Topic Test - Period 3](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/2-1-7-end-of-topic-test-period-3.md)
- 2.2 Group 2
  - [2.2.1 Group 2 Chemistry](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/2-2-1-group-2-chemistry.md)
- 2.3 Group 17
  - [2.3.1 Introduction to Halogens](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/2-3-1-introduction-to-halogens.md)
  - [2.3.2 Reactions of Halogens](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/2-3-2-reactions-of-halogens.md)
  - [2.3.3 Chlorine & Chlorate(I)](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/2-3-3-chlorine-and-chloratei.md)
  - [2.3.4 End of Topic Test - Group 17](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/2-3-4-end-of-topic-test-group-17.md)
  - [2.3.5 A-A* (AO2/3) - Periodicity, Group 2 & 17](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/2-3-5-a-a-ao23-periodicity-group-2-and-17.md)
- 2.4 Transition Metals
  - [2.4.1 General Properties](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/2-4-1-general-properties.md)
  - [2.4.2 Titrations](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/2-4-2-titrations.md)
  - [2.4.3 Shapes of Complex Ions](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/2-4-3-shapes-of-complex-ions.md)
  - [2.4.4 Variable Oxidation States](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/2-4-4-variable-oxidation-states.md)
  - [2.4.5 Ligands](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/2-4-5-ligands.md)
  - [2.4.6 Colours of Ions](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/2-4-6-colours-of-ions.md)
  - [2.4.7 Stereoisomerism of Complex Ions](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/2-4-7-stereoisomerism-of-complex-ions.md)
  - [2.4.8 Cisplatin](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/2-4-8-cisplatin.md)
  - [2.4.9 Ligand Substitutions & Kstab](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/2-4-9-ligand-substitutions-and-kstab.md)
  - [2.4.10 End of Topic Test - Transition Metals](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/2-4-10-end-of-topic-test-transition-metals.md)
  - [2.4.11 A-A* (AO2/3) - Transition Metals](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/2-4-11-a-a-ao23-transition-metals.md)
- 2.5 Nitrogen & Sulfur
  - [2.5.1 Nitrogen & Ammonia](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/2-5-1-nitrogen-and-ammonia.md)
  - [2.5.2 Formulated vs Manure Fertilisers](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/2-5-2-formulated-vs-manure-fertilisers.md)
  - [2.5.3 Nitrogen Containing Fertilisers](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/2-5-3-nitrogen-containing-fertilisers.md)
  - [2.5.4 Fertilizers & Eutrophication](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/2-5-4-fertilizers-and-eutrophication.md)
  - [2.5.5 Common Atmospheric Pollutants & Their Properties](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/2-5-5-common-atmospheric-pollutants-and-their-properties.md)
  - [2.5.6 Catalytic Converters](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/2-5-6-catalytic-converters.md)
  - [2.5.7 Atmospheric Oxides](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/2-5-7-atmospheric-oxides.md)

### 3 Organic Chemistry & Analysis
- 3.1 Introduction to Organic Chemistry
  - [3.1.1 Naming Conventions](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-1-1-naming-conventions.md)
  - [3.1.2 Mechanism](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-1-2-mechanism.md)
  - [3.1.3 Isomerism](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-1-3-isomerism.md)
  - [3.1.4 End of Topic Test - Introduction to Organic Chem](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-1-4-end-of-topic-test-introduction-to-organic-chem.md)
- 3.2 Hydrocarbons
  - [3.2.1 Fractional Distillation](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-2-1-fractional-distillation.md)
  - [3.2.2 Cracking](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-2-2-cracking.md)
  - [3.2.3 Combustion](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-2-3-combustion.md)
  - [3.2.4 Chlorination](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-2-4-chlorination.md)
  - [3.2.5 End of Topic Test - Alkanes](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-2-5-end-of-topic-test-alkanes.md)
  - [3.2.6 Introduction to Alkenes](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-2-6-introduction-to-alkenes.md)
  - [3.2.7 Reactions of Alkenes](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-2-7-reactions-of-alkenes.md)
  - [3.2.8 Polymerisation Reactions](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-2-8-polymerisation-reactions.md)
  - [3.2.9 End of Topic Test - Alkenes](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-2-9-end-of-topic-test-alkenes.md)
  - [3.2.10 Arenes](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-2-10-arenes.md)
  - [3.2.11 Evidence for Structure of Arenes](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-2-11-evidence-for-structure-of-arenes.md)
  - [3.2.12 Reactions of Benzene](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-2-12-reactions-of-benzene.md)
  - [3.2.13 End of Topic Test -Arenes](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-2-13-end-of-topic-test-arenes.md)
- 3.3 Halogen Derivatives
  - [3.3.1 Properties of Haloalkanes](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-3-1-properties-of-haloalkanes.md)
  - [3.3.2 Substitution Reactions of Haloalkanes](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-3-2-substitution-reactions-of-haloalkanes.md)
  - [3.3.3 Environmental Impacts of Haloalkanes](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-3-3-environmental-impacts-of-haloalkanes.md)
  - [3.3.4 End of Topic Test - Halogenoalkanes](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-3-4-end-of-topic-test-halogenoalkanes.md)
- 3.4 Hydroxy Compounds
  - [3.4.1 Types of Alcohol](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-4-1-types-of-alcohol.md)
  - [3.4.2 Oxidation 1](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-4-2-oxidation-1.md)
  - [3.4.3 Oxidation 2](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-4-3-oxidation-2.md)
  - [3.4.4 Elimination](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-4-4-elimination.md)
  - [3.4.5 Acids & Esters](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-4-5-acids-and-esters.md)
  - [3.4.6 Acyl Chlorides & Acylation](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-4-6-acyl-chlorides-and-acylation.md)
  - [3.4.7 Phenols & Their Reactions](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-4-7-phenols-and-their-reactions.md)
  - [3.4.8 End of Topic Test - Alcohols](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-4-8-end-of-topic-test-alcohols.md)
- 3.5 Carbonyl Compounds
  - [3.5.1 Carbonyls](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-5-1-carbonyls.md)
  - [3.5.2 Hydrogen Bonding & Carbonyls](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-5-2-hydrogen-bonding-and-carbonyls.md)
  - [3.5.3 Aldehydes & Ketones](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-5-3-aldehydes-and-ketones.md)
  - [3.5.4 Tri-Iodomethane Reaction](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-5-4-tri-iodomethane-reaction.md)
  - [3.5.5 End of Topic Test -Carbonyls](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-5-5-end-of-topic-test-carbonyls.md)
- 3.6 Carboxylic Acids & Derivatives
  - [3.6.1 Properties of Carboxylic Acids](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-6-1-properties-of-carboxylic-acids.md)
  - [3.6.2 Esters](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-6-2-esters.md)
  - [3.6.3 Acyl Chlorides](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-6-3-acyl-chlorides.md)
  - [3.6.4 End of Topic Test - Carboxylic Acids](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-6-4-end-of-topic-test-carboxylic-acids.md)
- 3.7 Nitrogen Compounds
  - [3.7.1 Nature & Preparation of Amines](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-7-1-nature-and-preparation-of-amines.md)
  - [3.7.2 Basicity & Nucleophilicity](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-7-2-basicity-and-nucleophilicity.md)
  - [3.7.3 Amides](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-7-3-amides.md)
  - [3.7.4 Reactions of Amino Acids](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-7-4-reactions-of-amino-acids.md)
  - [3.7.5 Amino Acids](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-7-5-amino-acids.md)
- 3.8 Polymerisation
  - [3.8.1 Properties of Addition Polymers](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-8-1-properties-of-addition-polymers.md)
  - [3.8.2 Condensation Polymerisation](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-8-2-condensation-polymerisation.md)
  - [3.8.3 Effects of Side-Chains on Polymers](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-8-3-effects-of-side-chains-on-polymers.md)
  - [3.8.4 Hydrolysis of Ester & Amide Groups](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-8-4-hydrolysis-of-ester-and-amide-groups.md)
  - [3.8.5 Proteins](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-8-5-proteins.md)
  - [3.8.6 DNA](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-8-6-dna.md)
  - [3.8.7 Adhesive & Conducting Polymers](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-8-7-adhesive-and-conducting-polymers.md)
  - [3.8.8 End of Topic Test - Amines & Proteins](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-8-8-end-of-topic-test-amines-and-proteins.md)
- 3.9 Analytical Techniques
  - [3.9.1 Chromatography](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-9-1-chromatography.md)
  - [3.9.2 High-Performance Liquid Chromatography](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-9-2-high-performance-liquid-chromatography.md)
  - [3.9.3 Gas Chromatography](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-9-3-gas-chromatography.md)
  - [3.9.4 IR Spectroscopy](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-9-4-ir-spectroscopy.md)
  - [3.9.5 Uses of IR Spectroscopy](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-9-5-uses-of-ir-spectroscopy.md)
  - [3.9.6 Mass Spectrometry](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-9-6-mass-spectrometry.md)
  - [3.9.7 Mass Spectrometry Analysis](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-9-7-mass-spectrometry-analysis.md)
  - [3.9.8 Nuclear Magnetic Resonance](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-9-8-nuclear-magnetic-resonance.md)
  - [3.9.9 Carbon-13 NMR](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-9-9-carbon-13-nmr.md)
  - [3.9.10 Proton NMR I](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-9-10-proton-nmr-i.md)
  - [3.9.11 Proton NMR II](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-9-11-proton-nmr-ii.md)
  - [3.9.12 End of Topic Test - Analytical Techniques](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-9-12-end-of-topic-test-analytical-techniques.md)
  - [3.9.13 A-A* (AO2/3) - Analytical Techniques](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-9-13-a-a-ao23-analytical-techniques.md)
- 3.10 Organic Synthesis
  - [3.10.1 Chirality & Drug Synthesis](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-10-1-chirality-and-drug-synthesis.md)
  - [3.10.2 Organic Synthesis](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-10-2-organic-synthesis.md)
  - [3.10.3 Examples of Synthetic Routes](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-10-3-examples-of-synthetic-routes.md)
  - [3.10.4 End of Topic Test - Organic Synthesis](https://senecalearning.com/en-gb/revision-notes/international-a-level/chemistry/cambridge-international/3-10-4-end-of-topic-test-organic-synthesis.md)