Nuclear Radiation Natural Radioactivity Nuclear Equations Producing Radioactive

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

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

Radiation • Radiation comes from the nucleus of an atom. • Unstable nucleus emits a particle or energy alpha beta gamma 3

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

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

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

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

Radiation Protection 8

Balancing Nuclear Equations In the reactants and products Atomic numbers must balance and Mass numbers must balance 9

Alpha decay 10

Beta decay 234 Th 90 ® 234 Pa 91 + 0 e 1 beta particle 11

Gamma radiation No change in atomic or mass number 11 B 5 5 + 0 0 boron atom in a high-energy state 12

Learning Check NR 1 Write the nuclear equation for the beta emitter Co-60. 13

Solution NR 1 Write the nuclear equation for the Beta emitter Co-60. 60 Co 60 Ni 27 28 + 0 e -1 14

Producing Radioactive Isotopes Bombardment of atoms produces radioisotopes = 60 59 Co = 60 + 1 n 27 0 = 27 cobalt atom 56 Mn + 25 4 H e 2 = 27 neutron manganese alpha radioisotope particle 15

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

Solution NR 2 What radioactive isotope is produced in the following bombardment of boron? 10 B 5 + 4 He 2 13 N 7 + 1 n 0 nitrogen radioisotope 17

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

Examples of Half-Life Isotope C-15 Ra-224 Ra-223 I-125 C-14 U-235 Half life 2. 4 sec 3. 6 days 12 days 60 days 5700 years 710 000 years 19

Learning Check NR 3 The half life of I-123 is 13 hr. How much of a 64 mg sample of I-123 is left after 26 hours? 20

Solution NR 3 t 1/2 = 13 hrs 26 hours = 2 x t 1/2 Amount initial = 64 mg Amount remaining = 64 mg x ½ = 16 mg 21

Nuclear Fission large nuclei break up 235 U 92 + 1 n 0 139 Ba 56 + 94 Kr 36 + 3 1 n + Energy 0 22

Fission 23

Nuclear Fusion small nuclei combine 2 H 1 + 3 H 4 He 1 2 + 1 n + Energy 0 Occurs in the sun and other stars 24

Learning Check NR 4 Indicate if each of the following are (1) Fission (2) fusion A. B. C. D. Nucleus splits Large amounts of energy released Small nuclei form larger nuclei Hydrogen nuclei react Energy 25

Solution NR 4 Indicate if each of the following are (1) Fission (2) fusion A. B. C. D. 1 1+2 2 2 Nucleus splits Large amounts of energy released Small nuclei form larger nuclei Hydrogen nuclei react 26