40. NUCLEAR MEDICINE: ALPHA DECAY

Question 1

1. What was the first mode of Radioactive Decay that was detected?

Answer 1

• Alpha (⍺) decay
• it was investigated during the 1980s

Question 2

2. What happens during Alpha Decay?

Answer 2

• the atomic nucleus emits an alpha particle
• the energy and the charge are always conserved

Question 3

3. What characterises Alpha Decay?

Answer 3

• a nuclear transformation

Question 4

4. How does an unstable parent nucleus (P) attain a more stable nuclear configuration?

Answer 4

• it does this through the ejection of an Alpha particle

Question 5

5. What is the name given to the more stable nuclear configuration?

Answer 5

• the daughter nucleus
• D

Question 6

6. What is an alpha particle?

Answer 6

• it is a Helium 4 nucleus
• it has a very stable configuration
• it consists of 2 protons
• it consists of 2 neutrinos

Question 7

7. How is the number of protons and neutrons conserved during Alpha decay?

Answer 7

• a He nucleus is produced
• this is the alpha particle

Question 8

8. What are the effects of the production of an Alpha Particle?

Answer 8

• the parent’s Atomic Mass number (A) is lowered by 4
• the parent’s Atomic number (Z) is lowered by 2

THERE ARE NOW:
- 2 less protons
- 2 less neutrons

Question 9

9. What happens when an Alpha Particle is emitted by a Radioactive Parents nucleus?

Answer 9

• the atomic number of the parent decreases by 2

-it sheds two orbital electrons from its outermost shell

• the energetic alpha particle slows down through the
  absorbed

Question 10

10. What is the result of the Alpha particle slowing down?

Answer 10

• 2 electrons can now be captured from its surroundings
• the He atom becomes neutral

Question 11

11. What range do Alpha particles have in the air?

Answer 11

• a range of about 1 cm to 10 cm

Question 12

12. What range do Alpha particles have in tissue?

Answer 12

• a range of about 10⎺³⁰ cm to 10⎺²⁰ cm

Question 13

13. What is the most important example of radioactive decay in Alpha Decay?

Answer 13

• the decay of Radium-226
• it has a half life of 1602 years

Question 14

14. What does Radium-226 decay into?

Answer 14

• Radon-222
• this has a half life of 3.8 days

THE ATOMIC MASS:
- is reduced by 4

THE ATOMIC NUMBER:
- is reduced by 2

Question 15

15. What is the Half-life?

Answer 15

• this is the amount of time is takes for a substance to
  decay to half of its activity