Coaching Centre
Chapter 8: From the Universe to the Atom Notes
HSC Physics Module 8: how radiation became matter after the Big Bang, Hubble's expanding universe, stellar spectra and the H–R diagram, fusion in stars, the discovery of the electron and the nucleus, Bohr's atom and the hydrogen spectrum, matter waves, radioactive decay and binding energy, fission and fusion, and the Standard Model of particle physics.
Sections
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8A From radiation to matter Mastered
How the early universe turned radiation into matter: the hot Big Bang, mass–energy equivalence E = mc², pair production and annihilation, the cooling sequence from quarks to nuclei to atoms, Big Bang nucleosynthesis of hydrogen and helium, recombination and the cosmic microwave background.
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8B Hubble and the expanding universe Mastered
How the expansion of the universe was discovered: Slipher's redshifts, Leavitt's period–luminosity law for Cepheid variables, Hubble's 1929 velocity–distance graph, Hubble's law v = H₀d, redshift, estimating the age of the universe from 1/H₀, and today's Hubble tension.
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8C Stellar spectra and classifying stars Mastered
How emission and absorption spectra are produced and how they compare with a continuous black-body spectrum, Wien's law, the Harvard spectral classes OBAFGKM, why the strength of hydrogen, helium, metal and molecular lines changes with temperature, Cecilia Payne's discovery of what stars are made of, and luminosity classes.
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8D The H–R diagram and stellar evolution Mastered
Using the Hertzsprung–Russell diagram at HSC level: luminosity, temperature, colour and radius; luminosity classes; what a star's position says about its mass and evolutionary stage; the main-sequence mass–luminosity–lifetime relation; and the evolutionary tracks of low-mass and high-mass stars to white dwarfs, neutron stars and black holes.
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8E Nucleosynthesis in stars Mastered
How stars make energy and new elements: applying E = mc² to the Sun's mass loss, the proton–proton chain and the CNO cycle in main-sequence stars, the triple-alpha process and later burning stages in post-main-sequence stars, why fusion stops at iron, and how the s-process, r-process, supernovae and neutron-star mergers make the heavy elements.
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8F Cathode rays and the electron Mastered
The discovery of the electron: investigations of cathode rays in evacuated tubes, the particle-or-wave debate, Thomson's measurement of the charge-to-mass ratio with crossed electric and magnetic fields, and Millikan's oil-drop experiment showing that charge is quantised.
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8G The nuclear atom Mastered
How the nucleus was discovered: Thomson's "plum pudding" model, the Geiger–Marsden alpha-scattering experiment and Rutherford's nuclear model, estimating the size of the nucleus, the limitations of Rutherford's model, and Chadwick's discovery of the neutron using conservation of momentum and energy.
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8H Bohr and the hydrogen spectrum Mastered
Bohr's model of the hydrogen atom and its postulates, energy levels and transitions with E = hf, the Balmer, Lyman and Paschen series, the Rydberg equation, ionisation energy, absorption, the limitations of Bohr's model, and measuring the Balmer series with a spectroscope.
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8I Matter waves and Schrödinger's atom Mastered
De Broglie's proposal that matter has a wavelength, λ = h/mv; how standing electron waves explain Bohr's allowed orbits; the experimental evidence from Davisson and Germer and from G. P. Thomson's electron diffraction; why everyday objects show no wave behaviour; Heisenberg's uncertainty principle; and Schrödinger's contribution to the modern model of the atom with orbitals and quantum numbers.
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8J Radioactive decay and half-life Mastered
Why some nuclei are unstable, the band of stability on the N–Z chart, alpha, beta-minus, beta-plus and gamma decay with balanced nuclear equations, properties of the radiations, decay series, the exponential decay law N = N₀e^(−λt), the decay constant and half-life, activity, and modelling half-life in the laboratory.
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8K Binding energy, fission and fusion Mastered
Mass defect and binding energy, the binding energy per nucleon curve and why both fission and fusion release energy, calculating the energy released in alpha decay, artificial transmutation, fission and fusion, chain reactions and critical mass, how fission reactors work including Australia's OPAL reactor, and fusion power research.
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8L Deep inside the atom Mastered
Evidence that protons and neutrons are made of quarks, the particle zoo and new particles from cosmic rays and accelerators, the Standard Model of matter with quarks, leptons and force-carrying bosons, the quark composition of hadrons, conservation laws in particle reactions, and how linear accelerators, cyclotrons, synchrotrons and the Large Hadron Collider test the Standard Model.
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8M From the Universe to the Atom: review Mastered
Module 8 review: a summary of the origins of the elements, the structure of the atom, the quantum mechanical atom, the nucleus and the Standard Model, all the formulas in one place, how the ideas connect, key words, and a mixed HSC-style test.