1. DOMAIN 4 Energy Transformations: RADIOACTIVITY

2. What is nuclear radiation? Particles and energy released from an unstable nucleus May cause damage to living tissue

3. What is radioactivity? The process by which an unstable nucleus releases particles or energy (nuclear radiation) in order to become more stable All atoms with unstable nuclei are radioactive

4. What are 3 types of radiation? Alpha (  ) helium nucleus paper 2+  Beta (  )  electron 1- lead  Gamma (  )  high-energy photon 0 concrete

5. Types of Radiation RadiationSymbolChargeStopped By:Description Alpha α 2+Sheet of paperMade of 2 protons and 2 neutrons (He nucleus) Beta β 1-3mm of aluminum Fast-moving electrons formed when a neutron in the nucleus breaks apart into a proton and an electron Gamma γ 07cm of leadAn electromagnetic wave of extremely high frequency and short wavelength; Not made of matter and do not have electric charge

6. Strength of Radiation

7. What is nuclear decay? The process in which atomic nuclei emit particles or energy to become more stable 3 Types of nuclear decay: – Alpha decay – Beta decay – Gamma decay

8. Alpha decay Occurs when the nucleus releases an alpha particle (2p and 2n) Decreases the mass number of the nucleus by 4 (# protons decreases by 2) A new atom is formed Ex: U-238, Ra-226

9. Which one shows alpha decay?

10. Beta Decay Occurs when a beta particle is released from a nucleus (beta particle is an electron formed inside the nucleus when a neutron breaks apart – a proton is also formed) Mass number stays the same and atomic number increases by 1 A new atom is formed Ex: C-14

11. Which one shows beta decay?

12. Gamma Decay Involves the release of a gamma ray Nucleus does not change into a different nucleus (no new atom is formed) Alpha and beta decay are almost always accompanied by gamma decay Because a gamma ray is an extremely high- energy wave, the nucleus makes a transition to a lower energy state No change in mass number or atomic number Ex: Po-210

13. Which one shows gamma decay?

15. What is transmutation? The process in which one element is changed into another as a result of changes in the nucleus Occurs when alpha or beta decay takes place

16. What is the half-life of a radioactive element? The time required for half of the sample of radioactive nuclei to decay Radioactive Substance Half-life C-145,730 years; decays into N-14 Ba-13986 minutes; decays into lanthanum-139 Rhodium-10630 seconds U-2384.5 billion years

17. Half-life problem How much of a 20-g sample of sodium-24 would remain after decaying for 30 hours? Sodium-24 has a half-life of 15 hours.

18. What is a radioisotope? A radioactive isotope (it is unstable and will decay into other elements until it reaches a stable form) Elements that are not radioactive may have isotopes that are radioactive

19. What is Potassium-40 used for? To calculate the age of rocks It decays into argon-40 so the ratio of K-40 to Ar-40 is smaller for older rocks

20. What is C-14 used for? To determine the age of organisms and objects less than 50,000 years old

21. What is nuclear fission? The process by which a nucleus splits into two or more smaller fragments, releasing neutrons and energy Ex:

22. Nuclear Power Fission Reactors Cooling Tower

23. Nuclear Power Fission Reactors

24. What is nuclear fusion? The process in which light nuclei combine at extremely high temperatures, forming heavier nuclei and releasing energy Nuclear fusion produces the sun’s energy when hydrogen nuclei combine Hydrogen nuclei are fused together to produce a helium atom and a huge amount of energy

25. FUSION

26. Nuclear Power Fusion Reactors (not yet sustainable)

27. Nuclear Power Fusion Reactors (not yet sustainable) Tokamak Fusion Test Reactor Princeton University National Spherical Torus Experiment

28. Nuclear Power 235 U is limited danger of meltdown toxic waste thermal pollution Hydrogen is abundant no danger of meltdown no toxic waste not yet sustainable FISSIONFISSION FUSIONFUSION vs.

29. Other Uses of Radiation: – Irradiated Food – Radioactive Dating – Nuclear Medicine

30. Is all radiation dangerous? No, visible light is a form of radiation but has a wavelength that does not harm us We are exposed to radiation from natural sources on a daily basis (background radiation)