AQA Boards Chemistry

3.1.1.1 Fundamental Particles

• Appreciate that knowledge and understanding of atomic structure has evolved over time.
• Protons, neutrons and electrons: relative charge and relative mass.
• An atom consists of a nucleus containing protons and neutrons surrounded by electrons.

3.1.1.3 Electron Configuration

• Electron configurations of atoms and ions up to Z = 36 in terms of shells and sub-shells (orbitals) s, p and d.

3.2.5.4 Formation of coloured ions (A-level only)

• Colour arises when some of the wavelengths of visible light are absorbed and the remaining wavelengths of light are transmitted or reflected.
• The energy difference between the ground state and the excited state of the d electrons is given by:

ΔE = hν = hc/λ

• The absorption of visible light is used in spectroscopy

For some projects involving transition metals

3.2.5.1 General properties of transition metals (A-level only)

• Transition metal characteristics of elements Ti–Cu arise from an incomplete d sub-level in atoms or ions. The characteristic properties include: formation of coloured ions and variable oxidation state.

3.2.5.4 Formation of coloured ions (A-level only)

• d electrons move from the ground state to an excited state when light is absorbed
• Changes in oxidation state, co-ordination number and ligand alter ΔE and this leads to a change in colour.

3.2.5.5 Variable oxidation states (A-level only)

• Transition elements show variable oxidation states.