As we go down a group, the nuclear charge increases as the number of protons increase but this is outweighed by the increase in shielding and the increased distance from nucleus due to the additional quantum shell being added.As there are more shells the atomic radius increases. The nuclear attraction decreases so the first ionisation energy decreases down a group.The general trend is repeated in group 2, 5, 6 and 7.In group 4 lead(Pb) is an anomaly because it has a higher ionisation energy than tin(Sn).There is no general trend in first ionisation energies in group 3.
Ionisation Energy Down a Group
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Specification: Edexcel Chemistry (8CH0), AS-level, Topic 1: Atomic Structure and the Periodic Table. Topic: Atomic Structure.
Key terms in this lesson
- shielding
- The repulsion of outer shell electrons by electrons in filled inner shells, which reduces the nuclear attraction they feel.
- ionisation energy
- The energy needed to remove one electron from each atom in one mole of gaseous atoms, forming one mole of gaseous 1+ ions.
More in Atomic Structure
- Orbitals
- Electronic Configurations
- Predicting Electronic Configuration
- Energy Levels and Emission Spectra
- First Ionisation Energy
- Successive Ionisation Energies
- The Energy of an Electron
- Ionisation Energy across a Period
All 19 lessons in Atomic Structure · All Edexcel AS-level Chemistry topics