2. Radioactive Decay Read pages 191-196 157

3. THE STRONG NUCLEAR FORCE STRONG NUCLEAR FORCE Atoms are held together by

4. There are different types of nuclear radiationdifferent types Alpha particles Beta particles Gamma rays Neutron emission

5. Alpha particles Positively charged More massive than other types Released in the disintegration of radioactive elements Consists of two protons and two neutrons http://library.thinkquest.org/3471/radiation_types_body.html A helium nucleus, which carries a charge of.

7. Beta particle A charged electron emitted during certain types of radioactive decay Neutrons decay to form a proton and a high speed electron The electron is ejected

8. Neutron emission is a type of radioactive decay of atoms containing excess neutrons, in which a neutron is simply ejected from the nucleus. radioactive decayneutrons

9. Gamma rays High energy photon emitted by a nucleus during fission and radioactive decay

10. What stops it? Alpha Beta Gamma

11. Isotope An atom with a different number of neutrons is called an isotope Hydrogen usually is a proton and an electron If it has a neutron it is considered an isotope Hydrogendeuteriumtritium 0 neutrons1 neutron2 neutrons

12. Half-lives The rate of decay of an isotope is called the half- life. A half life is the amount of time it takes for half of the amount to decay. It is constant Different elements have different half-lives Radium-226=1620 years Uranium-238 = 4.5 billion years Uranium-238

13. 200g radium -226half-life of 1620years 100g1620 50g3240 _____g4860 12.5g_______ 6.25g8100 ________g9720 1.5625g_______ 158

14. Table Design Half life Amount remaining Time Past 1234512345

15. Periodic Table Practice Lithium 7 Li 3 3P 4N mass Atomic number Atomic symbol Mass=p + n Neutrons = mass - protons

16. REMEMBER— this is all about isotopes Atomic number = # of protons You absolutely must figure your own mass or number of neutrons Don’t use the chart Mass = protons + neutrons Neutrons = Mass – protons

17. Radiation in Everyday Life