Ch 9 Nuclear Radiation

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2

Learning Check

To predict the product, simply remember that the mass number and atomic number are conserved

What is the identity of X?

Slide 14

Learning Check

Write the nuclear equation for the beta emitter Co-60.

Slide 15

Solutions

60Co 60Ni + 0 e

27 28 -1

93

239

Np

Slide 16

Producing Radioactive Isotopes

Bombardment of atoms produces radioisotopes

= 60 = 60

59Co + 1n 56Mn + 4H e

27 0 25 2

= 27 = 27

cobalt neutron manganese alpha

atom radioisotope particle

Slide 17

Learning Check

What radioactive isotope is produced in the following bombardment of boron?

10B + 4He ? + 1n

5 2 0

Slide 18

Solution

What radioactive isotope is produced in the following bombardment of boron?

10B + 4He 13N + 1n

5 2 7 0

nitrogen

radioisotope

Slide 19

Half-Life of a Radioisotope

The time for the radiation level to fall (decay) to one-half its initial value

Slide 20

Examples of Half-Life

Isotope Half life

C-15 2.4 sec

Ra-224 3.6 days

Ra-223 12 days

I-125 60 days

C-14 5700 years

U-235 710 000 000 years

Slide 21

Learning Check

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

Slide 22

Solution

t1/2 = 13 hrs

26 hours = 2 x t1/2

Amount initial = 64mg

Amount remaining = 64 mg x ½ x ½

= 16 mg

Slide 23

Fission VS Fusion

Fission

large nuclei break up

235U + 1n 139Ba + 94Kr + 3 1n +

92 0 56 36 0

Energy

Slide 24

Fission of Uranium-235

Chain reaction – the reaction sustains itself by producing more neutrons

Slide 25

Nuclear Fusion

Fusion

small nuclei combine

2H + 3H 4He + 1n +

1 1 2 0

Occurs in the sun and other stars

Energy

Excessive heat can not be contained