Matter and Its Properties · SHS1 Chemistry

Lesson notes

Learning Objectives

Indicator: 1.1.1.LI.6 - Describe the cathode rays experiment and alpha particles scattering experiment and identify the weaknesses of J. J. Thompson and Rutherford’s models of the atom.

By the end of the lesson, learners can:

Describe the key features of J. J. Thomson’s cathode ray experiment, including the apparatus used and the behaviour of cathode rays in electric and magnetic fields.
Describe Rutherford’s alpha particle scattering experiment, including the setup and the observed results.
Explain the conclusions drawn from each experiment about the structure of the atom.
Identify the weaknesses of Thomson’s plum pudding model and Rutherford’s nuclear model.
Construct a labelled model or diagram of the atom based on evidence from both experiments.

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Curriculum details

Strand: Physical Chemistry (Strand 1)
Sub-strand: Matter and Its Properties (1.1)
Content standard: 1.1.1.CS.1 - Demonstrate understanding of the scientific practices in chemistry using relevant acquired skills to solve problems as well as explaining the structure of the atom and its stability. 1.1.1.LO.1 Use the knowledge and understanding of the scientific practices in Chemistry to explain the structure of the atom as well as the stability of its nucleus. 1.1.1.LO.2 Use the mole concept to determine the amount and quantity of various substances involved in chemical reactions. 1.1.1.LO.3 Write mole ratios for chemical equations and apply it in quantitative analysis. 1.1.1.LO.4 Use the kinetic theory of matter to explain the behaviour of solids, liquids and gases under different conditions and describe the laboratory preparation of gases as well as their uses in everyday life.
Indicator: 1.1.1.LI.6 - Describe the cathode rays experiment and alpha particles scattering experiment and identify the weaknesses of J. J. Thompson and Rutherford's models of the atom.
Suggested placement: Semester 1, Week 6 (Week 6 of the year)
Our suggestion, laid out in curriculum order across three terms of twelve weeks. NaCCA does not fix the week, so follow your school's scheme of learning.
Curriculum reference: NaCCA curriculum document, p. 29

Exemplars (from the NaCCA curriculum)

Activity-Based Learning: In mixed-ability groups,
- Use simulation or videos or charts to investigate the properties of cathode rays under the following headings: a. Effect in a magnetic field, b. Effect in electric field c. Effect on photographic plate.
- Use simulation to investigate or chart to illustrate or video to show and describe J. J. Thompson's cathode ray experiment and Rutherford's alpha scattering experiment.
- Describe the structure of the atom based on analysis of the evidence gathered from both experiments.
Project-Based Learning: Individually or in groups,
- Construct a model to represent the atom.
- Draw a diagram of the atom modelled
- Display the model and diagram for class discussion.
Teaching and Learning Materials:
- * ICT devices * Household items with labels * Chemical containers with labels * Containers having chemical assay * Personal protective equipment (goggles, laboratory coat/apron, hand gloves etc) * * Http://www.kentchemistry.com/links/atomicstructure/PauliHundsRule.htm Hydrogen peroxide * * Http://www.youtube.com.watch?v=2AFPfg0come
- Hydrazine * * Http://www.khanacademy.com Oxidising materials * * Https://www.youtube.com/watch?v=ZIAyNFLRFuw Flammable materials * * https://phet.colorado.edu/en/simulations/rutherford-scattering Acetic acid and nitric acid * * https://www.khanacademy.org/science/chemistry/electronic-structure-of-
- Worksheets with incomplete nuclear reactions with prepared mark schemes * * http//www.youtube.com/watch?v=PpOAlj7sOEc Worksheets of empty orbital diagram for learners to complete * Worksheets with blank column for numbers of proton, neutrons and electrons * Fire extinguisher * Fire blanket * * Charts of hazard, prohibition and mandatory Material for setting fire * * Videos or charts of wrong practices in
- Markers * * Chart of the mass spectrometer Cardboard
- * Potassium permanganate and glycerol * Counters with up and down orientation to represent electron spin-pairing and boxes to represent orbitals * Modelling clay (plasticine) * Clay * Styrofoam * Calculator
- Models: Use One balloon per s orbital, per p-orbital, three (different coloured) subshell of P orbital
- WEBSITES * Chemsketch or simulation for filling atomic
- atoms/history-of-atomic-structure/a/discovery-of-the-electron
- * https://www.khanacademy.org/science/chemistry/electronic-structure-of- atoms/history-of-atomic-structure/v/rutherfords-gold-foil-experiment * Http//www.youtube.com/watch?v=m92QR7CBNoQ
- CHARTS
- * Mass spectrogram for analyses * Charts of experimental set-up of J. J.
- Rutherford's alpha particle scattering * Charts of line and continuous spectra
- Chart showing how the energy levels in series
- two balloons joined at their knots pairs of balloons to make one
- orbitals
- symbols the chemical laboratory
- Thompson's experiment and experiment
- the hydrogen give rise to spectral
Assessment (1.1.1.AS.6). The document marks these depth-of-knowledge levels for this indicator: Level 2 Skills of conceptual understanding.