1. Nuclear Chemistry Types of Radioactivity

2. What is radioactivity? The emission of high energy particles from the nucleus of an atom.

3. What are some sources of Radioactivity?

4. Can you see radioactivity? Hear? Taste? Feel? Smell?

5. How did man find out about it? 1896 - Henri Becquerel accidentally left some uranium salt in a drawer with a photographic plate –developed film showed an outline of the uranium salt on the film. –concluded an invisible energy that exposed the film. –This is called radiation.

6. How did man find out about it? Becquerel's photographic plate. In the exposure at the bottom of the image, he has found that he could absorb the radiations, casting the shadow of a Maltese cross that was placed between the plate and the uranium salts.

7. Radioactive Elements Radioactive elements all have high atomic numbers –Remember: The atomic number represents the number of protons in the nucleus The number of protons determines what the element is. Nucleus is held together by “strong force”

8. Remember this….

9. Radioactive Elements Larger atoms – harder to hold together This makes it possible for particles to escape the nucleus This is radioactive decay Any element that has an atomic number greater than 83, is radioactive.

10. Nuclear Notation

11. Isotopes of elements differ in their number of neutrons in the nucleus This gives them a different atomic mass. The nucleus of an isotope with a certain atomic number and mass is called a nuclide. Radiation energy is given off from unstable (large) nuclides. –Radioactive decay

12. Isotopes of elements Isotopes of elements differ in the ratio of neutrons to protons. –This ratio affects the stability of the nucleus In smaller atoms the nucleus is stable if the ratio is 1 to 1 In larger atoms the nucleus is stable if the ratio is 3 neutrons to 2 protons An atom can be unstable if it has too few or too many neutrons.

13. Chemical reactions involve changes in the number or configuration of electrons. Nuclear reactions involve the protons and neutrons found in the nucleus.

14. Nuclear Reactions During nuclear reactions, a nucleus can lose or gain protons and neutrons Remember: adding or taking away protons changes the identity of the element An alchemist’s dream!!

15. Radioactive Decay The release of radiation

16. Radioactive Decay There are 3 types of radiation.

17. Alpha α Decay Alpha particles are given off when a nucleus releases 2 protons and 2 neutrons

18. Alpha α Decay Alpha particle is the same as the nucleus of a Helium atom Has a 2+ charge and an atomic mass of 4 Is the largest and slowest form of radiation It is the least penetrating –Can be stopped by a sheet of paper But still can be deadly

19. Alpha α Decay Alpha decay follows the form:

20. Alpha α Decay + + +

21. Beta β Decay Beta particles are electrons escaping from the nucleus of an atom. Created by the spontaneous break down of a neutron to a proton and an electron. Beta particles are faster and more penetrating than Alpha particles Can be stopped by a sheet of aluminum foil.

22. Beta β Decay Carbon-14 is an example of an isotope that decays by beta emission

23. Beta β Decay Beta negative decay follows the form:

24. Beta β Decay + + +

25. Gamma γ Waves have very high frequency, short wavelengths have no mass and no charge. Travel at the speed of light. Usually released along with Beta or Alpha particles. The most penetrating form of radiation Lead and concrete are used as barriers for gamma waves. Can cause great harm to living cells

26. Gamma γ Waves Gamma decay follows the form:

27. Electromagnetic radiation

28. Alpha, Beta, Gamma