Unit 8: Atomic Physics

Unit Themes and Emphases

Focussing Questions

Unit D: Atomic Physics

Themes: Energy and Matter
Overview: In this unit, students study the development and modification of models of the structure of matter.
This unit builds on:
  • • Science 9, Unit E: Space Exploration
  • • Physics 20, Unit C: Circular Motion, Work and Energy
  • • Physics 30, Unit A: Momentum and Impulse, Unit B: Forces and Fields and Unit C: Electromagnetic Radiation
This unit prepares students for further study of the nature of matter in post-secondary studies in physics. Unit D will require approximately 25% of the time allotted for Physics 30.

Focusing Questions:
  • How is the atom organized?
  • How can a model of(SI the atom and the nucleus be subjected to experimental tests?
  • How does knowledge of the internal structure of the atom lead to the development of applications of energy supply and to the technology of diagnostic imaging?
General Outcomes: There are four major outcomes in this unit.
Students will:
  1. 1. describe the electrical nature of the atom
  2. 2. describe the quantization of energy in atoms and nuclei
  3. 3. describe nuclear fission and fusion as powerful energy sources in nature
  4. 4. describe the ongoing development of models of the structure of matter.
Key Concepts: The following concepts are developed in this unit and may also be addressed in other units or in other courses. The intended level and scope of treatment is defined by the learning outcomes.
  • • charge-to-mass ratio (Thomson’s experiment)
  • • classical model of the atom (Rutherford, Bohr)
  • • spectra: continuous, line emission and line absorption
  • • energy levels (states)
  • • de Broglie hypothesis
  • • quantum mechanical model
  • • half-life
  • • nuclear decay
  • • nuclear reactions
  • • Standard Model of matter
General Outcome

D1 Students will describe the electrical nature of the atom.

Specific Outcomes for Knowledge Students will:

30–D1.1k describe matter as containing discrete positive and negative charges

30–D1.2k explain how the discovery of cathode rays contributed to the development of atomic models

30–D1.3k explain J. J. Thomson’s experiment and the significance of the results for both science and technology

30–D1.4k explain, qualitatively, the significance of the results of Rutherford’s scattering experiment, in terms of scientists’ understanding of the relative size and mass of the nucleus and the atom.


Specific Outcomes for Science, Technology and Society (STS) (Nature of Science Emphasis)
Students will:

30–D1.1sts explain that scientific knowledge may lead to the development of new technologies, and new technologies may lead to or facilitate scientific discovery (ST4) [ICT F2–4.4]

  • • analyze how the identification of the electron and its characteristics is an example of the interaction of science and technology
  • • analyze the operation of cathode-ray tubes and mass spectrometers.

Specific Outcomes for Skills (Nature of Science Emphasis)
Initiating and Planning
Students will:

30–D1.1s formulate questions about observed relationships and plan investigations of questions, ideas, problems and issues

  • • identify, define and delimit questions to investigate; e.g., “What is the importance of cathode rays in the development of atomic models?” (IP–NS1)
  • • evaluate and select appropriate procedures and instruments for collecting evidence and information, including appropriate sampling procedures; e.g., use electric and magnetic fields to determine the charge-to-mass ratio of the electron (IP–NS4) [ICT C6–4.5, F1–4.2].
Performing and Recording
Students will:

30–D1.2s conduct investigations into relationships among observable variables and use a broad range of tools and techniques to gather and record data and information

  • • perform an experiment, or use simulations, to determine the charge-to-mass ratio of the electron (PR–NS2, PR–NS3) [ICT C6–4.4, F1–4.2].
Analyzing and Interpreting
Students will:

30–D1.3s analyze data and apply mathematical and conceptual models to develop and assess possible solutions

  • • determine the mass of an electron and/or ion, given appropriate empirical data (AI–NS3)
  • • derive a formula for the charge-to-mass ratio that has input variables that can be measured in an experiment using electric and magnetic fields (AI–NS6).
Communication and Teamwork
Students will:

30–D1.4s work collaboratively in addressing problems and apply the skills and conventions of science in communicating information and ideas and in assessing results

  • • select and use appropriate numeric, symbolic, graphical and linguistic modes of representation to communicate findings and conclusions (CT–NS2).
General Outcome

D2 Students will describe the quantization of energy in atoms and nuclei.

Specific Outcomes for Knowledge Students will:

30–D2.1k explain, qualitatively, how emission of EMR by an accelerating charged particle invalidates the classical model of the atom

30–D2.2k describe that each element has a unique line spectrum

30–D2.3k explain, qualitatively, the characteristics of, and the conditions necessary to produce, continuous line-emission and line-absorption spectra

30–D2.4k explain, qualitatively, the concept of stationary states and how they explain the observed spectra of atoms and molecules

30–D2.5k calculate the energy difference between states, using the law of conservation of energy and the observed characteristics of an emitted photon

30–D2.6k explain, qualitatively, how electron diffraction provides experimental support for the de Broglie hypothesis

30–D2.7k describe, qualitatively, how the two-slit electron interference experiment shows that quantum systems, like photons and electrons, may be modelled as particles or waves, contrary to intuition.


Specific Outcomes for Science, Technology and Society (STS) (Nature of Science Emphasis) Students will:

30–D2.1sts explain that scientific knowledge and theories develop through hypotheses, the collection of evidence, investigation and the ability to provide explanations (NS2)

  • • investigate and report on the use of line spectra in the study of the universe and the identification of substances
  • • investigate how empirical evidence guided the evolution of the atomic model

30–D2.2sts explain that scientific knowledge may lead to the development of new technologies, and new technologies may lead to or facilitate scientific discovery (ST4) [ICT F2–4.4]

  • • investigate and report on the application of spectral or quantum concepts in the design and function of practical devices, such as street lights, advertising signs, electron microscopes and lasers.

Specific Outcomes for Skills (Nature of Science Emphasis) Initiating and Planning
Students will:

30–D2.1s formulate questions about observed relationships and plan investigations of questions, ideas, problems and issues

  • • predict the conditions necessary to produce line-emission and line-absorption spectra (IP–NS3)
  • • predict the possible energy transitions in the hydrogen atom, using a labelled diagram showing energy levels (IP–NS3).
Performing and Recording
Students will:

30–D2.2s conduct investigations into relationships among observable variables and use a broad range of tools and techniques to gather and record data and information

  • • observe line-emission and line-absorption spectra (PR–NS2)
  • • observe the representative line spectra of selected elements (PR–NS2)
  • • use library and electronic research tools to compare and contrast, qualitatively, the classical and quantum models of the atom (PR–NS1) [ICT C1–4.1, C7–4.2].
Analyzing and Interpreting
Students will:

30–D2.3s analyze data and apply mathematical and conceptual models to develop and assess possible solutions

  • • identify elements represented in sample line spectra by comparing them to representative line spectra of elements (AI–NS6) [ICT C7–4.2].
Communication and Teamwork
Students will:

30–D2.4s work collaboratively in addressing problems and apply the skills and conventions of science in communicating information and ideas and in assessing results

  • • select and use appropriate numeric, symbolic, graphical and linguistic modes of representation to communicate findings and conclusions (CT–NS2).

General Outcome

D3 Students will describe nuclear fission and fusion as powerful energy sources in nature.

Specific Outcomes for Knowledge
Students will:

30–D3.1k describe the nature and properties, including the biological effects, of alpha, beta and gamma radiation

30–D3.2k write nuclear equations, using isotope notation, for alpha, beta-negative and beta-positive decays, including the appropriate neutrino and antineutrino

30–D3.3k perform simple, nonlogarithmic half-life calculations

30–D3.4k use the law of conservation of charge and mass number to predict the particles emitted by a nucleus

30–D3.5k compare and contrast the characteristics of fission and fusion reactions

30–D3.6k relate, qualitatively and quantitatively, the mass defect of the nucleus to the energy released in nuclear reactions, using Einstein’s concept of mass-energy equivalence.


Specific Outcomes for Science, Technology and Society (STS) (Nature of Science Emphasis)
Students will:

30–D3.1sts explain that the goal of science is knowledge about the natural world (NS1)

  • • investigate the role of nuclear reactions in the evolution of the universe (nucleosynthesis, stellar expansion and contraction)
  • • investigate annihilation of particles and pair production

30–D3.2sts explain that the products of technology are devices, systems and processes that meet given needs and that the appropriateness, risks and benefits of technologies need to be assessed for each potential application from a variety of perspectives, including sustainability (ST6, ST7) [ICT F2–4.2, F3–4.1]

  • • assess the risks and benefits of air travel (exposure to cosmic radiation), dental X-rays, radioisotopes used as tracers, food irradiation, use of fission or fusion as a commercial power source and nuclear and particle research
  • • assess the potential of fission or fusion as a commercial power source to meet the rising demand for energy, with consideration for present and future generations.

Specific Outcomes for Skills (Nature of Science Emphasis) Initiating and Planning
Students will:

30–D3.1s formulate questions about observed relationships and plan investigations of questions, ideas, problems and issues

  • • predict the penetrating characteristics of decay products (IP–NS3).
Performing and Recording
Students will:

30–D3.2s conduct investigations into relationships among observable variables and use a broad range of tools and techniques to gather and record data and information

  • • research and report on scientists who contributed to the understanding of the structure of the nucleus (PR–NS1).
Analyzing and Interpreting
Students will:

30–D3.3s analyze data and apply mathematical and conceptual models to develop and assess possible solutions

  • • graph data from radioactive decay and estimate half-life values (AI–NS2) [ICT C6–4.3]
  • • interpret common nuclear decay chains (AI–NS6)
  • • graph data from radioactive decay and infer an exponential relationship between measured radioactivity and elapsed time (AI–NS2) [ICT C6–4.3]
  • • compare the energy released in a nuclear reaction to the energy released in a chemical reaction, on the basis of energy per unit mass of reactants (AI–NS3).
Communication and Teamwork
Students will:

30–D3.4s work collaboratively in addressing problems and apply the skills and conventions of science in communicating information and ideas and in assessing results

  • • select and use appropriate numeric, symbolic, graphical and linguistic
General Outcome

D4 Students will describe the ongoing development of models of the structure of matter.

Outcomes for Knowledge
Students will:

30–D4.1k explain how the analysis of particle tracks contributed to the discovery and identification of the characteristics of subatomic particles

30–D4.2k explain, qualitatively, in terms of the strong nuclear force, why high-energy particle accelerators are required to study subatomic particles

30–D4.3k describe the modern model of the proton and neutron as being composed of quarks

30–D4.4k compare and contrast the up quark, the down quark, the electron and the electron neutrino, and their antiparticles, in terms of charge and energy (mass-energy)

30–D4.5k describe beta-positive (β β+) and beta-negative (β β-) decay, using first-generation elementary fermions and the principle of charge conservation (Feynman diagrams are not required).


Specific Outcomes for Science, Technology and Society (STS) (Nature of Science Emphasis)
Students will:

30–D4.1sts explain that concepts, models and theories are often used in interpreting and explaining observations and in predicting future observations (NS6a)

  • • research and report on the development of models of matter

30–D4.2sts explain that scientific knowledge is subject to change as new evidence becomes apparent and as laws and theories are tested and subsequently revised, reinforced or rejected (NS4)

  • • observe how apparent conservation law violations led to revisions of the model of the atom; i.e., an apparent failure of conservation laws required the existence of the neutrino

30–D4.3sts explain that scientific knowledge may lead to the development of new technologies, and new technologies may lead to or facilitate scientific discovery (ST4) [ICT F2–4.4]

  • • investigate how high-energy particle accelerators contributed to the development of the Standard Model of matter.

Specific Outcomes for Skills (Nature of Science Emphasis)
Initiating and Planning
Students will:

30–D4.1s formulate questions about observed relationships and plan investigations of questions, ideas, problems and issues

  • • predict the characteristics of elementary particles, from images of their tracks in a bubble chamber, within an external magnetic field (IP–NS3).
Performing and Recording
Students will:

30–D4.2s conduct investigations into relationships among observable variables and use a broad range of tools and techniques to gather and record data and information

  • • research, using library and electronic resources, the relationships between the fundamental particles and the interactions they undergo (PR–NS1) [ICT C1–4.1].
Analyzing and Interpreting
Students will:

30–D4.3s analyze data and apply mathematical and conceptual models to develop and assess possible solutions

  • • analyze, qualitatively, particle tracks for subatomic particles other than protons, electrons and neutrons (AI–NS2) [ICT C7–4.2]
  • • write β β+ and β- β- decay equations, identifying the elementary fermions involved (PR–NS4)
  • • use hand rules to determine the nature of the charge on a particle (AI–NS6)
  • • use accepted scientific convention and express mass in terms of mega electron volts per c2 (MeV/c2), when appropriate (AI–NS1).
Communication and Teamwork
Students will:

30–D4.4s work collaboratively in addressing problems and apply the skills and conventions of science in communicating information and ideas and in assessing results

  • • select and use appropriate numeric, symbolic, graphical and linguistic modes of representation to communicate findings and conclusions (CT–NS2).

Links to Mathematics
The following mathematics outcomes are related to the content of Unit D but are not considered prerequisites.
 Concept  Mathematics Course, Strand and Specific Outcome
 Data Collection and Analysis  Grade 9 Mathematics, Statistics and Probability (Data Analysis), Specific Outcome 3
 Measurement and Unit Conversions  Mathematics 10C, Measurement, Specific Outcomes 1 and 2;
 Mathematics 10-3, Measurement, Specific Outcome 1;
 Mathematics 20-3, Algebra, Specific Outcome 3
 Trigonometry  Mathematics 10C, Measurement, Specific Outcome 4;
 Mathematics 10-3, Geometry, Specific Outcomes 2 and 4
 Rate and Proportions  Mathematics 20-2, Measurement, Specific Outcome 1
 Graph Analysis  Mathematics10C, Relations and Functions, Specific Outcomes 1, 4 and 7;
 Mathematics 20-3, Statistics, Specific Outcome 1
 Mathematics 30-1, Relations and Functions, Specific Outcomes 9 and 14
 Mathematics 30-2, Relations and Functions, Specific Outcome 6
 Solving Equations  Mathematics 30-1, Relations and Functions, Specific Outcome 10;
 Mathematics 30-2, Relations and Functions, Specific Outcome 3
 Scale Diagrams  Mathematics 20-2, Measurement, Specific Outcome 2;
 Mathematics 20-3, Geometry, Specific Outcome 2
 Slope  Mathematics10C, Relations and Functions, Specific Outcomes 3 and 5;
 Mathematics 20-3, Algebra, Specific Outcome 2
 Powers  Mathematics10C, Algebra and Number, Specific Outcome 3




Chapter 17: The development of models of the structure of matter is ongoing

Key Concepts

  • charge-to-mass ratio
  • quantum mechanical model
  • standard model of matter

Knowledge

  • explain the discovery and identification of subatomic particles
  • explain why high-energy particle accelerators are required
  • describe the modern model of the proton and neutron
  • compare and contrast elementary particles and their antiparticles
  • describe beta decays

Science, Technology, and Society

  • explain the use of concepts, models, and theories
  • explain the link between scientific knowledge and new technologies

Flippity Review Questions for Chapter 17

Flippity Review QR Code

 




17.1 Detecting and Measuring Subatomic Particles

Cloud and Bubble Chambers
Both show the path of particles traveling through as the particles energy causes a trail through the gas in the chamber. By applying a magnetic field across the chamber the particle’s path curves allowing measurements to be taken.


 


17.2 Quantum Theory and The Discovery of New Particles

In 1928 Paul Dirac combined Einstein’s theory of relativity and Schrodinger’s wave equations of the atom and predicted the existence of antimatter. Antimatter is matter with an opposite charge (electron that is positive, positron)
In 1932 Carl Anderson photographed the first proof of antimatter. It was a particle with the charge to mass ratio of an electron but curved the opposite direction in a magnetic field.
Antimatter is the same as regular matter except that it has the opposite electric charge.
Matter plus antimatter changes mass into energy.
Quantum Field Theory
Forces: electrostatics, gravity, weak nuclear and strong nuclear force are created by the exchange of mediating particles (virtual). These virtual particles travel back and forth between the involved actual particles.


 


17.3 Probing the Structure of Matter

Subatomic particles (smaller than proton and neutron) are groups of particles found only in particle accelerators and are being researched to determine how they interact.
They are described by their mass as energy per speed of light squared.
See equation sheet


 


17.4 Quarks and the Standard Model

The Quark Model
Protons and neutrons are mostly made of three quarks
Neutron – 2 down and 1 up quark
Proton – 2 up and 1 down quark