SL + HL
E.1 Structure of the atom
What is inside an atom, and how do we know? E.1 follows the evidence: the Geiger–Marsden–Rutherford experiment that found the nucleus, and the line spectra that show an atom has only certain energy levels. HL adds the distance of closest approach, the size and density of nuclei, deviations from Rutherford scattering and the Bohr model of hydrogen.
The big idea in one minute
E = hf = hc/λ · Ek = k(2e)(Ze)/d (HL) · R = R₀A^⅓ (HL) · mvr = nh/2π, E = −13.6/n² eV (HL)
Most alpha particles pass straight through a gold foil, but a very few bounce back: the positive charge and most of the mass sit in a tiny nucleus. Atoms emit and absorb light only at certain wavelengths: each line is a photon whose energy equals the gap between two discrete energy levels.
Your path through E.1
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Concept builders
Core work
Structure of the atom notes
The full topic: worked examples, the markscheme words and the common mistakes.
Levelled practice
Levels 1–4 with hints and worked answers. Goal: a ★ at Level 2 in every topic. For a 6 or 7, get Levels 3 and 4 too.
IB-format practice
Timed papers with markschemes, done as homework or classwork. One attempt: your report goes to your teacher.
10-question quiz
10 questions, 30 minutes, one attempt. Your teacher gives you the answers later.
Extra help
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Flashcards
Cards for quick recall of definitions and equations. Good before a quiz.