Is Atomic Structure tested in Paper 1?

Yes. Paper 1 MCQs regularly include quantum number assignments, electron configurations of ions, and ionisation energy comparisons. Multi-statement questions often combine configuration knowledge with periodic trend reasoning.

Do I need to memorise ionisation energy values?

No. The SEAB Chemistry Data Booklet provides ionisation energies and other atomic data. You are expected to interpret and explain trends using the values given, not reproduce them from memory.

What is the most common question type for this topic in Paper 2?

Interpret or sketch a photoelectron spectrum, and explain successive ionisation energy graphs. Both require you to link peak positions or jump patterns to electron configurations and effective nuclear charge.

How should I explain an ionisation energy anomaly in an exam answer?

Name the specific subshells involved (e.g. 2s vs 2p), state which is higher in energy or why it is more shielded, then relate this to why less energy is needed to remove the electron - typically two to three concise sentences earns full marks. --- Struggling with Atomic Structure? Our H2 Chemistry tuition programme covers this topic with structured practice, Paper 4 practical drills, and worked exam solutions. --- Consistent practice with spectra, ionisation graphs, and configuration anomalies will keep Core Idea 1 solid. Pair these notes with the broader study hub at https://eclatinstitute.sg/blog/h2-chemistry-notes for drills across the rest of the syllabus, and keep the official data booklet guide handy for constants/tables you’ll cite in exam questions: https://eclatinstitute.sg/blog/h2-chemistry-notes/H2-Chemistry-Data-Booklet-2026. ---

H2 Chemistry Atomic Structure Notes | A-Level 9476

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10 Feb 2025, 00:00 Z· Last updated 13 Jan 2026

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Q: What does H2 Chemistry Notes: Topic 1 - Atomic Structure cover?
A: Review quantum numbers, electron configurations, ionisation trends, and spectroscopy evidence for the Core Idea 1 Atomic Structure topic in the 2026 H2 Chemistry syllabus.

Atomic structure underpins every other area of H2 Chemistry. You need to know how quantum numbers define electron positions, how orbitals fill, and how evidence from spectroscopy backs the quantum model. These notes focus on the ideas that repeatedly appear in structured and data-based questions.

Status: SEAB H2 Chemistry (9476, first exam 2026) syllabus and Chemistry Data Booklet last checked 2026-01-13. Core Idea 1: Atomic Structure is assessed across Papers 1–3 (with data booklet support where relevant). For the full topic map and paper weightings, see our H2 Chemistry Syllabus 2026-27 overview.

Quick revision box

What this topic tests: Quantum numbers, electron configurations, ionisation trends, spectroscopy evidence.
Top mistakes to avoid: Mixing up subshell filling order; weak PES justification; missing shielding language in trend explanations.
20-minute sprint plan: 5 min quantum numbers + filling order; 10 min trend explanation drill; 5 min PES interpretation.

1 Quantum Numbers at a Glance

Symbol	Name	Typical values	What it tells you
$n$	Principal quantum number	$1, 2, 3, ...$

H2 Chemistry Atomic Structure Notes | A-Level 9476

Quick revision box

1 Quantum Numbers at a Glance

Sources

Key reminders

2 Electron Configurations

3 Ionisation Energy Trends

3.1 Successive ionisation energies

3.2 Factors affecting first ionisation energy

3.3 Evidence from photoelectron spectroscopy (PES)

4 Worked Example

5 Exam Skills Check

6 Misconceptions to Fix

7 Quick Practice Prompts

Common exam mistakes

Frequently asked questions

Next step

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