1. TOPIC: RadioactivityTOPIC: Radioactivity & Natural Transmuations Do Now: Where on your reference table can you find radioactive particles?

2. Not all isotopes are stable Stable isotopes have… 1:1 ratio of n 0 to p + (for elements <20) 1.5:1 ratio of n 0 to p + (for elements >20)

3. Beyond Element 83 are very unstable (radioactive) No amount neutrons can hold nucleus together once it has 83 + protons All Elements 83 and above on PT are radioactive Other elements may have radioactive isotopes applet

4. Radioisotopes- unstable nucleus – they are radioactive the nucleus of element emits subatomic particles and/or electromagnetic waves… by emitting these particles, nucleus changes into different element (it’s trying to become more stable)

5. Radioactive Decay Series Sometimes 1 transmutation isn’t enough to achieve stability Some radioisotopes go through several changes before they achieve stability (and are no longer radioactive)

6. U-238  PB-206

7. Transmutation-When an element turns into a different element. This occurs when the number of protons changes.

8. These subatomic particles that are emitted were discovered around 1900 Alpha rays Beta rays Gamma rays

10. Radioactivity – Rutherford again!

11. Penetration & Shielding

12. 2 Neutrons & 2 Protons Charge = +2 Mass = 4amu 4 2 He

13. Beta Particle – fast moving electron

14. Transmutation 2 types – Natural – Artificial

15. Natural Transmutation Happens all by itself (spontaneous) Not affected by anything in environment 1 term on reactant side Original isotope 2 terms on product side Emitted Particle New Isotope

16. Natural Transmutation 16 N  0 e + 16 O 7 8 1 term on reactant side 2 terms on product side

17. Balancing Nuclear Equations 16 N  0 e + 16 O 7 8 Conservation of mass number: 16 = 0 + 16 Conservation of atomic number: 7 = -1 + 8

18. 232 Th  4 He + X 902 Conservation of Mass Number: sum of mass numbers on left side must = sum of mass numbers on right side Y Z 232 = 4 + Y so Y = 228

19. 232 Th  4 He + 228 X902 Conservation of Atomic Number: sum of atomic numbers on left side must = sum of atomic numbers on right side Z 90 = 2 + Z so Z = 88