Module 8: From the Universe to the Atom
11 dot points across 4 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.
Inquiry Question 3: How is it known that classical physics cannot explain the properties of the atom?
- Investigate the line emission spectra to examine the Balmer-Rydberg equation 1/lambda = R(1/n_f^2 - 1/n_i^2), and assess the limitations of the Bohr model of the hydrogen atom
A focused answer to the HSC Physics Module 8 dot point on the Bohr model of hydrogen. Postulates of stationary orbits and quantised angular momentum, the energy levels E_n = -13.6 eV / n^2, the Balmer-Rydberg formula 1/lambda = R (1/n_f^2 - 1/n_i^2), spectral series (Lyman, Balmer, Paschen), and the limitations of the model.
9 min answer → - Investigate de Broglie's matter waves, and the experimental evidence that confirms their existence including the Davisson-Germer experiment, and how matter waves explain the stability of Bohr orbits
A focused answer to the HSC Physics Module 8 dot point on de Broglie matter waves. The hypothesis lambda = h/p applied to electrons and to macroscopic objects, the Davisson-Germer electron diffraction experiment, and the standing-wave reinterpretation of Bohr's quantised orbits.
8 min answer → - Investigate the contribution of Schrodinger to the current model of the atom, including the probabilistic interpretation of the wavefunction and the concept of atomic orbitals replacing Bohr's fixed orbits
A focused answer to the HSC Physics Module 8 dot point on Schrodinger's contribution to the atom. The wavefunction psi, the probability density |psi|^2, the time-independent Schrodinger equation for bound states, atomic orbitals (s, p, d, f) replacing Bohr orbits, and the resolution of multi-electron spectra.
8 min answer →
Inquiry Question 2: How is it known that atoms are made up of protons, neutrons and electrons?
- Investigate, assess and model the experimental evidence supporting the existence and properties of the electron, including cathode ray tube experiments and Thomson's determination of the charge-to-mass ratio of the electron
A focused answer to the HSC Physics Module 8 dot point on the discovery and properties of the electron. Cathode ray tubes and the particle vs wave debate, Thomson's crossed-field experiment to measure the charge-to-mass ratio e/m, and his plum-pudding model of the atom.
8 min answer → - Investigate, assess and model Millikan's oil drop experiment to determine the elementary charge and the quantisation of electric charge
A focused answer to the HSC Physics Module 8 dot point on Millikan's oil drop experiment. Balancing gravity and electrical force on charged oil droplets between parallel plates, the equation mg = qE with E = V/d, the integer-multiple distribution of measured charges, and the value of the elementary charge e.
7 min answer → - Investigate and analyse the Geiger-Marsden (Rutherford) gold foil experiment and Rutherford's nuclear model of the atom, and Chadwick's discovery of the neutron
A focused answer to the HSC Physics Module 8 dot point on the structure of the atom. The Geiger-Marsden gold foil experiment, Rutherford's nuclear model replacing the plum pudding, and Chadwick's 1932 discovery of the neutron using beryllium-alpha collisions and conservation of momentum and energy.
9 min answer →
Inquiry Question 4: How is it known that human understanding of matter is still being refined?
- Account for the energy released in nuclear fission and fusion in terms of mass defect and binding energy, using E = mc^2 and the binding energy curve
A focused answer to the HSC Physics Module 8 dot point on nuclear energy. Mass defect Delta m = Z m_p + N m_n - m_nucleus, binding energy Delta m c^2, the binding-energy-per-nucleon curve with its iron peak, energy release in fission (heavy nuclei split) and fusion (light nuclei combine), and worked examples for both.
10 min answer → - Examine the radioactive decay of atomic nuclei (alpha, beta, gamma) and represent these decays as nuclear equations; use the decay law N = N_0 e^(-lambda t) and the concept of half-life T_1/2
A focused answer to the HSC Physics Module 8 dot point on radioactive decay. Alpha, beta-minus, beta-plus and gamma decay with nuclear equations, the decay law N = N_0 e^(-lambda t) and N = N_0 (1/2)^(t / T_1/2), and the relation lambda T_1/2 = ln 2.
9 min answer → - Investigate the Standard Model of matter, including quarks, leptons and the fundamental forces, and the role of particle accelerators in confirming the existence of these particles
A focused answer to the HSC Physics Module 8 dot point on the Standard Model. Three generations of quarks and leptons, the four fundamental forces and their gauge bosons (photon, W and Z, gluons, graviton), the role of particle accelerators in producing and detecting these particles, and the place of the Higgs boson.
9 min answer →
Inquiry Question 1: What evidence is there for the origins of the elements?
- Investigate the evidence for the Big Bang theory and the early evolution of the universe, including cosmic microwave background radiation, abundance of light elements, and Hubble's law v = H_0 d
A focused answer to the HSC Physics Module 8 dot point on the Big Bang and the origin of the elements. Hubble's law v = H_0 d as evidence for expansion, the cosmic microwave background as cooled relic radiation, primordial nucleosynthesis explaining the H/He ratio, and the timeline from the hot dense early universe to the present.
9 min answer → - Account for the production of emission and absorption spectra and compare these with a continuous black body spectrum; investigate stellar evolution using the Hertzsprung-Russell diagram and account for the synthesis of elements heavier than iron in supernovae
A focused answer to the HSC Physics Module 8 dot point on stars and the elements. The Hertzsprung-Russell diagram, main sequence to red giant to white dwarf or supernova evolution, hydrogen to helium fusion via the p-p chain and CNO cycle, heavier-element fusion up to iron, and the supernova production of elements heavier than iron via the r-process.
10 min answer →