1 Nuclear Radiation Natural Radioactivity Nuclear Equations Producing Radioactive Isotopes Half-Life Nuclear Fission and Fusion

2 Subatomic Particles Protons- positive charge In the nucleus Neutrons- neutral Electrons - negative charge Outside the nucleus

3 Radiation Electro-magnetic radiation comes from vibrating electrons, e.g., x-rays, light, uv rays Nuclear Radiation comes from the nucleus of an atom. Unstable nucleus emits a particle or energy  alpha  beta  gamma

4 Alpha Particle Same as a helium nucleus (He) 4 2 He or  Two protons Two neutrons

5 Beta Particle  An electron emitted from the nucleus 0 e or   1 A neutron in the nucleus breaks down 11 0 n H +e

6 Gamma  Radiation Pure radiation Like an X-ray but comes from the nucleus

7 Radiation Protection Shielding alpha – paper, clothing beta – lab coat, gloves gamma- lead, thick concrete Limit time exposed Keep distance from source

8 Radiation Protection

9 Nuclear Equations Beta decay will cause an increase in the atomic number since a Neutron has changed into a proton. But the mass remains the same. Alpha decay will cause a decrease in the atomic number and atomic mass since 2 protons and 2 neutrons are released as an alpha particle.

10 Alpha decay

11 Beta decay 234 Th  234 Pa + 0 e  1 beta particle

12 Gamma radiation No change in atomic or mass number 11 B 11 B + 0  boron atom in a high-energy state

13 Learning Check NR1 Write the nuclear equation for the beta emitter Co-60.

14 Solution NR1 Write the nuclear equation for the Beta emitter Co Co 60 Ni + 0 e

15 Producing Radioactive Isotopes Bombardment of atoms produces radioisotopes 59 Co + 1 n 56 Mn + 4 H e cobalt neutron manganese alpha atom radioisotope particle

16 Learning Check NR2 What radioactive isotope is produced in the following bombardment of boron? 10 B + 4 He ? + 1 n 5 2 0

17 Solution NR2 What radioactive isotope is produced in the following bombardment of boron? 10 B + 4 He 13 N + 1 n nitrogen radioisotope

18 Half-Life of a Radioisotope The time for the radiation level to fall (decay) to one-half its initial value decay curve 8 mg 4 mg2 mg 1 mg initial 1 half-life 2 3

19 Examples of Half-Life Isotope Half life C sec Ra days Ra days I days C years U years

20 Learning Check NR3 The half life of I-123 is 13 hr. How much of a 64 mg sample of I-123 is left after 26 hours?

21 Solution NR3 Half-life time =13 hrs 26 hours = 2 half-lives Amount initial =64mg Amount remaining = 64 mg x 1/2 x 1/2 = 16 mg

22 Nuclear Fission Fission large nuclei break up 235 U + 1 n 139 Ba + 94 Kr n Energy

23 Fission

24 Nuclear Fusion Fusion small nuclei combine 2 H + 3 H 4 He + 1 n Occurs in the sun and other stars Energy

25 Learning Check NR4 Indicate if each of the following are (1)Fission(2) fusion A.Nucleus splits B.Large amounts of energy released C.Small nuclei form larger nuclei D.Hydrogen nuclei react Energy

26 Solution NR4 Indicate if each of the following are (1)Fission(2) fusion A. 1 Nucleus splits B Large amounts of energy released C. 2 Small nuclei form larger nuclei D. 2 Hydrogen nuclei react