Radioactivity
Visão Geral
Some nuclei are simply not stable. Left completely alone, with nothing done to them at all, they break apart and fling out particles or energy at enormous speed. Nobody can predict which nucleus will go next, yet the behaviour of a whole sample is so regular that doctors, engineers and archaeologists build careers on it.
This lesson takes you from the structure of the nucleus to the three ionising radiations, their penetrating power, the meaning of half-life, and the real uses and real dangers of radioactive materials. Expect calculation questions on half-life and explanation questions on safety in your Edexcel papers.
Objetivos
- Describe the structure of an atom in terms of protons, neutrons and electrons and use symbols to describe particular nuclei
- Know the terms atomic (proton) number, mass (nucleon) number and isotope
- Know that alpha particles, beta particles and gamma rays are ionising radiations emitted from unstable nuclei in a random process
- Describe the nature of alpha particles, beta particles and gamma rays, and recall that they may be distinguished in terms of penetrating power and ability to ionise
- Investigate the penetration powers of different types of radiation using either radioactive sources or simulations
- Explain the sources of background (ionising) radiation from Earth and space
- Know the definition of the term half-life and understand that it is different for different radioactive isotopes
- Describe uses of radioactivity in industry and medicine
- Describe the difference between contamination and irradiation
- Describe the dangers of ionising radiations, including that radiation can cause mutations in living organisms, that radiation can damage cells and tissue, and the problems arising from the disposal of radioactive waste and how the associated risks can be reduced
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Avaliação da Lição
Parabéns por concluir a lição em Radioactivity. Agora que você explorou o conceitos e ideias-chave, é hora de colocar seu conhecimento à prova. Esta seção oferece uma variedade de práticas perguntas destinadas a reforçar sua compreensão e ajudá-lo a avaliar sua compreensão do material.
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- Which radiation is stopped by a single sheet of paper? A) Alpha B) Beta C) Gamma D) All three Answer: A
- Which radiation is the most penetrating? A) Alpha B) Beta C) Gamma D) They are all equal Answer: C
- A nucleus is written with mass number 40 and atomic number 19. How many neutrons does it contain? A) 19 B) 21 C) 40 D) 59 Answer: B
- A source has an activity of 1600 Bq and a half-life of 10 minutes. What is its activity after 30 minutes? A) 800 Bq B) 400 Bq C) 200 Bq D) 100 Bq Answer: C
- Which of the following is the largest natural contributor to background radiation in many countries? A) Nuclear power stations B) Radon gas from rocks C) Mobile phone masts D) Weapons fallout Answer: B
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