FIRST IONISATION ENERGIES Q&A - AQA Chemistry A-Level/AS

1. Define ionisation energy
2. Explain why 1st ionisation energy of elements down group 1 decreases even though the atomic number increases.
3. Explain why successive energies increase and how that proves the electronic configuration of Na
4. Explain the difference in first ionisation energies between Mg and Al
5. Explain the difference in first ionisation energies between P and S
6. Explain why first ionisation energies generally increase across a period

1. Ionisation energy is the energy given out when removing one mole of electrons from an atom of an element in a gaseous state.

2. First IE decreases down a group because as you go down, the atomic charge is the same but atomic radius increases. Due to increasing number of principle energy levels, the further away the outermost electron, the more shielding caused by the shells between it and the positive nucleas. Increased shielding means theres a weaker force of attraction between the outermost electron and nucleas, thus less energy required to remove.

3. Na = 1s²2s²2p…