3. Atomic Number & Mass Number • Atomic number = the number of protons • Mass number = the number of nucleons (protons & neutrons) • A neutral atom has the same number of protons and electrons.

4. Oxygen atom

5. Sodium atom

6. Aluminium atom

7. Copper atom

8. Platinum atom

9. Gold atom

10. Lead atom

11. Radium atom

12. Uranium atom

13. Use your periodic table to find… The number of protons in a carbon atom The number of protons in a sodium atom The number of neutrons in a sodium atom The number of protons in a copper atom The number of neutrons in a copper atom The number of protons in a lead atom The number of neutrons in a lead atom The number of electrons in a lead atom

14. How many neutrons are there in a chlorine atom? Some chlorine atoms have 18 neutrons. Some have 19… They are “isotopes” of chlorine. (Chlorine–35 and Chlorine-36)

15. Example: Carbon Isotopes

16. WORKSHEET ONE– first page only

17. Turning copper into gold?

18. Three types of Nuclear Reactions Radioactive decay Fusion Fission

19. Uranium atom

23. Alpha Radiation (α particle) • High-speed helium nucleus (+ve charge) • two protons & two neutrons • Can travel up to 10% of speed of light. • Range: a few centimetres • Can be stopped by a sheet of paper. • Can cause serious harm but cannot penetrate skin.

24. Beta Radiation (β particle) • High-energy electron (-ve charge) • Can travel up to 90% of speed of light. • Range: about 30 cm • Can be stopped by a sheet of aluminium about 5 mm thick.

25. Gamma Radiation (γRay) • Electromagnetic radiation with very high energy • Occurs as a result of a nucleus being left in a very excited state immediately following other types of radioactivity. • Travels at the speed of light. • Can penetrate through several centimetres of dense metal such as lead.

28. Finish WORKSHEET ONE