IGCSE+RADIOACTIVITY

Back to IGCSE PHYSICS IGCSE PARTICLES =IGCSE RADIOACTIVITY= media type="custom" key="12555628" [|BUILD AN ATOM SIM] [|ALPHA DECAY SIM] - these three all from PHET [|BETA DECAY SIM] - use them to understand how unstable nuclei decay [|RADIOACTIVE DATING SIM] - with game 7.2 describe the structure of an atom in terms of protons, neutrons and electrons and use symbols such as 14 6 C to describe particular nuclei
 * ~ 1 FORCES ||~ 2 ELECTRICITY ||~ 3 WAVES ||~ 4 ENERGY ||~ 5 SLG ||~ 6 MAGNETISM ||~ 7 RADIOACTIVITY ||

**BUILD AN ATOM ACTIVITY**

media type="custom" key="8437602" NUCLEUS: The dense core of the atom. It consists of protons and neutrons and is orbited by electrons. A proton is about the same mass as a neutron but about 2000 times larger than an electron.
 * MEET THE ELEMENTS VIDEO - song by They Might Be Giants **

UNSTABLE = RADIOACTIVE DECAY = DISINTEGRATE RANDOM = SPONTANEOUS eg the random disintegration of unstable nuclei
 * TERMINOLOGY**

7.3 understand the terms atomic (proton) number, mass (nucleon) number and isotope PROTON NUMBER, Z: The number of protons in a nucleus. Also known as the atomic number, it determines the element. Eg if Z=6, the atom is carbon. NUCLEON NUMBER, A: The number of protons plus neutrons in a nucleus. Also known as the mass number. ISOTOPES: Isotopes of an element are atoms which have the same number of protons but different numbers of neutrons. 7.4 understand that alpha and beta particles and gamma rays are ionising radiations emitted from unstable nuclei in a random process RADIOACTIVE NUCLEUS: Some nuclei are unstable and will decay by emitting a particle. They may do this several times, each time another element is formed. Eventually a stable isotope is reached.

7.5 describe the nature of alpha and beta particles and gamma rays and recall that they may be distinguished in terms of penetrating power

ACTIVITY: Research alpha, beta and gamma radiation on [|DARVILL WEBSITE] and then take the quiz. [|AND SOME GOOD PICS HERE]
 * RADIATION || ALPHA PARTICLE || BETA PARTICLE || GAMMA RAY ||
 * LETTER ||  ||   ||   ||
 * || [[image:alpha_particle.jpg]] || [[image:beta_particle.jpg]] ||  ||
 * NATURE ||  ||   ||   ||
 * MASS ||  ||   ||   ||
 * CHARGE ||  ||   ||   ||
 * SPEED ||  ||   ||   ||
 * IONISATION ||  ||   ||   ||
 * PENETRATION ||  ||   ||   ||
 * SYMBOL || 4 2 H ||  ||   ||

7.6 describe the effects on the atomic and mass numbers of a nucleus of the emission of each of the three main types of radiation ALPHA PARTICLE: A helium nucleus consisting of 2 protons and 2 neutrons. The electric charge is +2. Symbol: 4 2 He. An unstable nucleus can undergo alpha decay: BETA PARTICLE: An electron emitted from a nucleus when a neutron in the nucleus changes into a proton and an electron. The proton stays behind. The charge is -1.

GAMMA RAY: An energetic burst of electromagnetic radiation from an excited nucleus. It is not a particle. 7.7 understand how to complete balanced nuclear equations

**COPY AND COMPLETE THE NUCLEAR REACTION EQUATIONS BELOW** Fill in the blanks (you may need to go to [|webelements.com] to get some of the answers) Can you work out which is which? Choose from: //Alpha emission; Beta minus emission; Beta plus (positron) emission; Electron capture; Artificial synthesis of new element//



7.8 understand that ionising radiations can be detected using a photographic film or a Geiger-Muller detector 7.9 recall the sources of background radiation [|WIKIPEDIA'S ARTICLE ON BACKGROUND RADIATION] - a good description of the different sources [|CALCULATE YOUR ANNUAL DOSE OF RADIATION] - note the factors [|BRILLIANT XKCD CARTOON ON RADIATION DOSES]

bequerel (Bq): activity in decays per second. The curie is a non-SI unit measuring the same quantity. A rad is the energy absorbed by a particular mass of body The (milli)rem stands for Roentgen equivalent man - the dose in rad times a weighting factor. The SI unit is the sievert. BED - [|banana equivalent dose], yes really. Activity from a typical banana (mostly due to potassium isotopes) is 15 Bq.
 * UNITS OF RADIATION: **

ACTIVITY TO MODEL RADIOACTIVE DECAY USING COINS 7.10 understand that the activity of a radioactive source decreases over a period of time and is measured in becquerels

7.11 recall the term ‘half-life’ and understand that it is different for different radioactive isotopes [|KCVS RADIOACTIVE DECAY SIMULATION] 7.12 use the concept of half-life to carry out simple calculations on activity 7.13 describe the uses of radioactivity in medical and non-medical tracers, in radiotherapy and in the radioactive dating of archaeological specimens and rocks

[|PHET RADIOACTIVE DATING GAME] or download from Studywiz for speed

7.14 describe the dangers of ionising radiations, including:
 * radiation can cause mutations in living organisms
 * radiation can damage cells and tissue
 * the problems arising in the disposal of radioactive waste



**RADIOACTIVITY PRACTICE** **Information on elements at [|webelements.com]**
 * 1) Write a nuclear equation for the alpha decay of uranium-238.
 * 2) Write a nuclear equation for the beta minus decay of caesium-137.
 * 3) A nuclear sample has an activity of 300 Bq which falls to 75 Bq in 100 minutes. What is its half-life? [50 minutes]
 * 4) A sample containing 4 million nuclei has a half-life of 2 days. How many nuclei are remaining after 8 days? [250 000]
 * 5) In a lab, a detector detects 150 decays in one minute due to background radiation. It then measures a decay count of 18.5 Bq from a nuclear source in the same lab. What is the actual count? [16 Bq]

PRACTICE QUESTIONS IN RADIOACTIVE DECAY