1. 7.1 Part 1: Radioactivity & Isotopes

2. Radiation High energy rays and particles emitted by radioactive sources. (most invisible to human eyes) Includes: electromagnetic spectrum, alpha & beta particles. Electromagnetic Spectrum

3. Radioactivity The release of high-energy particles and rays from a substance due to changes in the nuclei of its atoms. Naturally occurring radiation found in our environment is called: “Natural Background Radiation” Radioactivity can be useful, such as in medical diagnoses and treatment (X-rays, Chemotherapy, etc.) and in generating electricity (Nuclear power plants)

4. Useful radiation… http://vimeo.com/78791415

5. Isotopes Atoms of the same element that have the… –Same number of protons (same atomic number) –Different number of neutrons Since the number of neutrons differs, the mass also differs. Different isotopes of the same element all have: –The same chemical symbol –The same atomic number (# of protons) –Different mass numbers

6. Use standard atomic notation –Symbol + Atomic number + Mass number –Also called “Nuclear Symbol” Representing Isotopes X Mass # Atomic # K 41 19 e.g.: Potassium has 3 naturally occurring isotopes. K 40 19 K 39 19 Potassium-39 Potassium-40 Potassium-41 Protons Neutrons Electrons 19 20 19 19 21 19 19 22 19

7. In nature, most elements are found as a mixture of isotopes. Atomic Mass Potassium-39Potassium-40Potassium-41 93.26%0.01%6.73% Each banana has the same relative abundance of potassium isotopes The atomic mass of an element that’s written on the periodic table is the average of all the naturally occurring isotopes. Atomic mass = (.9326 x 39) + (.0001 x 40) + (.0673 x 41) = 39.1

8. 1) Practice Problems p.291 #1-4 2) Workbook p.123-124