Playbook
Structure of Atom
70 q - 1.42/paper - 1% HARD, and halved in 2025. Bohr scaling, E = hc/λ and quantum numbers.
- Questions in the bank
- 70
- q/paper (2024–25 papers)
- 1.42
- Tagged HARD
- 1%
- Subtopics
- 6
Strand: Calculate
When you’ll see it
A Bohr orbit, an electron's wavelength or energy, a spectral line, quantum numbers, or isotopes and isoelectronic species.
How this chapter is tested
70 q at 1.42 a paper, 1% HARD — and it HALVED in 2025, from 2.00 a paper across 2023-24 to 1.00. Still set every year; give it fewer hours than 2023-24 papers suggest.
Bohr's model (18 q, never HARD) is scaling: rₙ = 0.529n²/Z Å, Eₙ = −13.6Z²/n² eV. Radiation is E = hν = hc/λ. The quantum-number rules decide which set is allowed, and the particles page counts protons, neutrons and electrons.
The sub-skills
The distinct skills inside the chapter, in the order to learn them.
Bohr scaling
r = 0.529 n²/Z Å, E = −13.6 Z²/n² eV, v ∝ Z/n.
Radiation
E = hν = hc/λ; de Broglie λ = h/mv.
Quantum numbers
l runs 0 to n − 1, m from −l to +l; a subshell holds 2(2l + 1) electrons.
Traps to expect
Distractor shapes this chapter reuses. The Traps page covers the patterns that cut across chapters.
An impossible quantum-number set
l must be less than n: (n = 2, l = 2) cannot exist. Such a set is planted among allowed ones.
Isoelectronic means same electrons
Na⁺, Mg²⁺ and F⁻ each have 10 electrons — isoelectronic, though their protons differ.
Learn it before you drill it
This chapter has full teaching notes — foundations, worked examples, self-checks and a per-subtopic mastery checkpoint. Read the notes once, then drill subtopic by subtopic below.
Structure of Atom notesDrill every structure of atom question
70 questions from the bank, scoped to 6 bundled subtopics.
Drill one subtopic at a time
The 6 subtopics this playbook covers, in catalog order.
- Subatomic Particles, Isotopes, Isobars and Isoelectronic SpeciesDrill
- Electronic Configuration and Pauli/Hund RulesDrill
- Electromagnetic Radiation and Wave PropertiesDrill
- Bohr's Atomic ModelDrill
- Quantum Mechanical Model, de Broglie, Heisenberg and Quantum NumbersDrill
- Hydrogen Spectrum and Rydberg EquationDrill
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