1.3.7 (HL)—Successive ionization energies
- Syllabus
- First assessment 2025
- Objective
- 1.3.7
- Level
- HL
Successive Ionization Energies
HL onlySuccessive ionization energies rise as electrons are removed. A very large increase occurs when removal crosses from the outer shell into a lower, more tightly held shell.
| Observation | Deduction |
|---|---|
| Small increases before the large jump | Electrons are being removed from the same outer shell |
| Large jump | The next electron is from an inner shell |
| Number removed before the jump | Outer-electron count and group pattern |
Use the position of the first large jump, not its numerical size alone, to infer the group.
A jump after three outer-electron removals is the pattern used in the study guide for a group 13 element. The same count-before-the-jump method applies to new data.
Locate the first order-of-magnitude jump before naming the group. A large jump after the second electron is removed shows two outer-shell electrons; the third electron would come from a lower shell, supporting a group 2 assignment.
Electron Configurations Summary
Retrieve the chain: emission lines reveal discrete levels; capacities, sublevels, orbitals, and spin rules build configurations; first and successive ionization energies then reveal how electrons are held and arranged.
When checking an answer, ask: Did I link a line to a transition? Did I use 2n² and the filling rules? Did I explain an ionization trend or count electrons before a successive-IE jump?