Chapter summary
Atomic Structure, at a glance
Use particles, orbitals and ionisation data to explain the behaviour of atoms and ions.
A-Level 8873, revised syllabus (2026-2027)
Quick revision
Revisit the essentials, then return to an explanation when you need it.
| Question | First move |
|---|---|
| How many neutrons/electrons? | Neutrons = A - Z; electrons = Z - signed charge. |
| Which way does a beam bend? | Positive to negative plate; negative to positive; neutral straight. |
| Which orbital fills? | 1s 2s 2p 3s 3p 4s 3d 4p; two per orbital, singly before pairing. |
| Which electron leaves an ion? | Remove outer-shell electrons; 4s before 3d for transition cations. |
| Why a different ionisation energy? | Compare charge, shielding, distance, subshell and pairing. |
| What does the large jump reveal? | Count electrons removed before reaching the inner shell. |