Discrete energy and radioactivity

Nature of science:

Accidental discovery: Radioactivity was discovered by accident when Becquerel developed photographic film that had accidentally been exposed to radiation from radioactive rocks. The marks on the photographic film seen by Becquerel probably would not lead to anything further for most people. What Becquerel did was to correlate the presence of the marks with the presence of the radioactive rocks and investigate the situation further. (1.4)

• Discrete energy and discrete energy levels
• Transitions between energy levels
• Radioactive decay
• Fundamental forces and their properties
• Alpha particles, beta particles and gamma rays
• Half-life
• Absorption characteristics of decay particles
• Isotopes
• Background radiation

• The geopolitics of the past 60+ years have been greatly influenced by the existence of nuclear weapons

Theory of knowledge:

• The role of luck/serendipity in successful scientific discovery is almost inevitably accompanied by a scientifically curious mind that will pursue the outcome of the “lucky” event. To what extent might scientific discoveries that have been described as being the result of luck actually be better described as being the result of reason or intuition?

• Describing the emission and absorption spectrum of common gases
• Solving problems involving atomic spectra, including calculating the wavelength of photons emitted during atomic transitions
• Completing decay equations for alpha and beta decay
• Determining the half-life of a nuclide from a decay curve
• Investigating half-life experimentally (or by simulation)

Guidance:

• Students will be required to solve problems on radioactive decay involving only integral numbers of half-lives
• Students will be expected to include the neutrino and antineutrino in beta decay equations

Data booklet reference:

• Knowledge of radioactivity, radioactive substances and the radioactive decay law are crucial in modern nuclear medicine
• How to deal with the radioactive output of nuclear decay is important in the debate over nuclear power stations (see Physics sub-topic 8.1)
• Carbon dating is used in providing evidence for evolution (see Biology sub- topic 5.1)
• Exponential functions (see Mathematical studies SL sub-topic 6.4; Mathematics HL sub-topic 2.4)

Aims:

• Aim 8: the use of radioactive materials poses environmental dangers that must be addressed at all stages of research
• Aim 9: the use of radioactive materials requires the development of safe experimental practices and methods for handling radioactive materials