1. Radioactive Decay Read pages 191-196 157

2. Atoms are held together by The strong nuclear force

3. There are different types ofnuclear radiation • Alpha particles • Beta particles • Gamma rays • Neutron emission

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

6. 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

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

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

9. What stops it? • Alpha • Beta • Gamma

10. Isotope •  An atom with a different number of neutrons is called an isotopeHydrogen usually is a proton and an electronIf it has a neutron it is considered an isotopeHydrogen deuterium tritium 0 neutrons 1 neutron 2 neutrons

11. 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-livesRadium-226=1620 yearsUranium-238 = 4.5 billion years

12. 158 200g radium -226 half-life of 1620years100g 162050g 3240_____g 486012.5g _______6.25g 8100________g 97201.5625g _______

13. Table Design Make a table for Table 1 problems!

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

15. 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

16. Radiation in Everyday Life