What happens if we keep removing electrons?
The General Trend: ALWAYS Increases
Successive IEs always increase because:
- Proton number stays constant.
- Electron number decreases → Less repulsion.
- Remaining electrons are pulled closer to the nucleus.
- 1st IE:738 kJ/mol
- 2nd IE:1450 kJ/mol
- 3rd IE:7730 kJ/mol (BIG JUMP)
The 'Big Jump' Evidence
The massive jump between the 2nd and 3rd IE of Magnesium proves that the 3rd electron exists in a new, inner, main energy level (closer to the nucleus, less shielding).
Logic: If it's easy to remove 2 electrons but very hard to remove the 3rd, the element must be in Group 2.
Identifying Group from Data
Paper 2 StyleThe successive ionization energies (kJ mol⁻¹) for an unknown element X are:
| 1st | 2nd | 3rd | 4th | 5th |
|---|---|---|---|---|
| 577 | 1820 | 2740 | 11600 | 14800 |
Identify the Group to which element X belongs.
1. Scan for the Jump: Look for the first massive increase (usually x4 or x5).
2. Locate: The jump happens between the 3rd and 4th IE.
3. Deduce: This means 3 electrons were relatively easy to remove (Valence Shell) before hitting the inner core.
4. Conclusion: Element X has 3 valence electrons, so it is in Group 13 (e.g., Al).