P2E – Nuclear Radiations 12/10/15 Learning Objective: Discuss the structure of an atom and nuclear radiation Learning Outcomes: Describe the structure of atoms Explain what nuclear radiation is State the three types of nuclear radiation and describe their penetrative properties Explain why ionizing (nuclear) radiation is harmful Describe some beneficial uses of nuclear radiation

Describe the structure of an atom Q1: Atoms have a small central nucleus made up of ____________ and neutrons around which there are ______________. Atoms have the same number of protons and electrons and therefore have no overall charge. They can be described as being ________. The number of protons found in the nucleus of an atom is called its ________ number. All atoms of a particular element have the same number of _____________. Atoms of different elements have different numbers of protons. The total number of protons and neutrons (nucleons) in an atom is called its _______________ number. Use the information on the following clip to answer Q1 on the sheet you have been given:

Q: What can you work out about the structure of a carbon atom from what you have learnt so far. Carbon has 6 protons Carbon has 6 electrons Carbon has an atomic mass of 12 Carbon therefore has 6 neutrons i.e. 12 – 6 = 6 A carbon atom has no charge (is neutral) Atomic number Mass number

What is nuclear radiation? Listen to the clip and use the information to fill in the “What is nuclear radiation” sheet you have been given.

What are the three types of nuclear radiation and how penetrative are they? Listen to the clip and/or watch the demonstration and use the information to fill in the “Properties of alpha, beta and gamma radiation” sheet you have been given.

Have a go at answering the exam questions you have been given. Q1: Mark scheme: any three from: Beta can pass through paper (1) Beta is stopped by aluminium (1) Gamma can pass through (paper and) aluminium / stopped by lead / B is gamma (1) Alpha is stopped by paper / C is alpha (1)

Define the term ion An ion is a charged particle. They can have either a positive (+) or negative (-) charge. The charge can also have a size. E.g. +2, -1 etc. Q: Suggest what happens to atoms that causes them to become positively or negatively charged. A: If atoms lose electrons they become positively charged and if they gain electrons they become negatively charged

What are ions? Sodium loses an electron and becomes positively charged Fluorine gains an electron and becomes negatively charged Metals always become positively charged whereas non-metals always become negatively charged Ions are charged particles. If they gain electrons they become negatively charged and if they lose electrons they become positively charged

Why is ionising radiation dangerous? Listen to the clip and use the information to fill in the “Why is ionising radiation dangerous” sheet you have been given.

Why is ionising radiation dangerous? Ionisation Proteins Kill Cancer Recover Mutates Cells Reactions Positive Unstable Negatively Radiation from radioactive sources causes __________. Ionising radiation may ____ cells. At lower doses cells may _______. However, at intermediate doses the radiation will change the structure of any atoms or absorb it. This is turn alters _______. This happens because the radiation may knock electrons off the atoms causing the formation of ________ ions. Alternatively, if electrons are gained by atoms then __________ charged ions are formed. This is dangerous because the ions are very _________. The ions cause chemical __________ within cells. For example, DNA that changes (___________) may cause a cell to divide in an uncontrolled way. This can lead to ________. Another danger of ionisation is that ___________ may change their shape and no longer work properly.

Why is ionising radiation dangerous? Radiation from radioactive sources causes ionisation. Ionising radiation may kill cells. At lower doses cells may recover. However, at intermediate doses the radiation will change the structure of any atoms or absorb it. This is turn alters cells. This happens because the radiation may knock electrons off the atoms causing the formation of positive ions. Alternatively, if electrons are gained by atoms then negatively charged ions are formed. This is dangerous because the ions are very unstable. The ions cause chemical reactions within cells. For example, DNA that changes (mutates) may cause a cell to divide in an uncontrolled way. This can lead to cancer. Another danger of ionisation is that proteins may change their shape and no longer work properly.

Beneficial uses You need to be able to describe beneficial uses of radiation. Watch the following clips and list some of the beneficial uses of alpha, beta and gamma radiation. Then match the use to the correct type of radiation. Finish by justifying your decisions. These include: As smoke detectors - To measure paper thickness - To treat cancer - In sterilisation - As radioactive tracers – In non-destructive testing - Alpha Beta Gamma Beta and gamma Gamma

Now use information to link the penetrative power of radiation to its uses. Q: Explain why alpha radiation is used instead of beta or gamma radiation in smoke detectors? Alpha radiation is absorbed by the smoke particles which triggers the smoke alarm. Beta and gamma radiation are both too penetrating to be absorbed by the smoke so would not work in smoke alarms.