neutrons within the nucleus. This was about 20 years after the nucleus became an accepted scientific idea. Students should be able to describe: • why the new evidence from the scattering experiment led to a change in the atomic • the difference between the plum pudding model of the atom and the nuclear model of the atom. Details of experimental work supporting the Bohr model are not required. Details of Chadwick’s experimental work are not required. a component of most nuclei, and outline its discovery. The students should now know the key properties of all three particles. Plenaries Not like a solar system (5 min) The students should make a list of similarities and particularly differences between atomic models and solar systems. I don’t believe it (10 min) Interactive where students choose the missing words to complete a paragraph summarising the evidence that led to the plum pudding model being replaced. Students then use this summary to write a letter to an unconvinced scientist who wants to hold on to the plum pudding model.
Atoms turn into positive ions if they lose one or more outer electron(s). Students should be able to relate differences between isotopes to differences in conventional representations of their identities, charges, and masses. 4.2.2 Nuclear equations are used to represent radioactive decay. The emission of the different types of nuclear radiation may cause a change in the mass and/or the charge of the nucleus. So alpha decay causes both the mass and charge of the nucleus to decrease. So beta decay does not cause the mass of the nucleus to change but does cause the charge of the nucleus to increase. Students are not required to recall two examples. Students should be able to use the names and symbols of common nuclei and particles to write balanced equations that show single alpha (α) notation, ensuring the students can identify the atomic number (proton number) and mass number (nucleon number). Students should calculate the number of neutrons in some examples. Discuss isotopes, showing some in nuclear notation and noting the difference in mass numbers. Alpha, beta, and gamma emission (30 min) Describe an alpha decay and the changes it causes in a nucleus. The students should look at an example and then try to construct a few additional equations by using a periodic table. Move on to beta emission, focusing on the change of a neutron to a proton and how this affects the decay equation. Show a few examples and ask the students to complete a few more. Discuss emission, pointing out that there is no change in the particle structure of the nucleus and so no decay equations are needed. Students then calculate changes in atomic number and mass number of an atom after it emits alpha and beta radiation. Plenaries Name that isotope (5 min) Students use the interactive to complete a table describing various isotopes. They need to fill in missing details such as element name, proton number, mass number, and number of electrons. Aiming for Grade 8 LOs: Explain why particles are ejected from the nucleus during nuclear decay. Describe the changes in the nucleus that occur during nuclear decay. Write full decay equations, for example, nuclear decays.
Coin toss (10 min) If someone has 120 coins and tosses them all, removing all of the heads after each toss, how many tosses until there are only 15 left? Lesson P7.6 Nuclear radiation in medicine WS: 1.5, 1.6 MS: 1b, 2c, 2f AQA spec link: 4.3.2 Students should be able to explain why the hazards associated with radioactive material differ according to the half-life involved. 4.3.3 Nuclear radiations are used in medicine for the: • exploration of internal organs Aiming for Grade 4 LOs: Name some medical applications for radioactive substances. State that the larger the dose of radiation, the more likely harm will be caused. Describe some precautions used during diagnoses or treatments involving radioactive substances.