Alpha Decay Examples in Smoke Detectors and Nuclear Medicine

📚 Quick Study Guide

• ⚛️ Alpha decay is a type of radioactive decay where an atomic nucleus emits an alpha particle (a helium nucleus, $^4_2He$).
• 🧪 The general equation for alpha decay is: $^A_ZX \rightarrow ^{A-4}_{Z-2}Y + ^4_2He$ where X is the parent nucleus and Y is the daughter nucleus.
• ☢️ Smoke detectors use Americium-241 ($^{241}Am$), which undergoes alpha decay to produce alpha particles that ionize the air inside the detector.
• 🩺 In nuclear medicine, alpha decay is sometimes used in targeted alpha therapy (TAT) to deliver radiation directly to cancer cells. Radium-223 ($^{223}Ra$) is an example of an alpha-emitting radionuclide used in therapy.
• ⏱️ Alpha decay half-lives vary widely depending on the nuclide, ranging from microseconds to billions of years.
• 💡 Key characteristics: Alpha particles have low penetration power and high ionizing power.

Practice Quiz

1. Which particle is emitted during alpha decay?

   1. Electron
   2. Proton
   3. Helium nucleus
   4. Neutron

2. What is the change in atomic number ($Z$) during alpha decay?

   1. Increases by 2
   2. Decreases by 2
   3. Increases by 4
   4. No change

3. Which radioactive isotope is commonly used in smoke detectors?

   1. Carbon-14
   2. Uranium-238
   3. Americium-241
   4. Iodine-131

4. What is the primary role of alpha particles in a smoke detector?

   1. To heat the air
   2. To create a magnetic field
   3. To ionize the air
   4. To block light

5. In nuclear medicine, what is the main advantage of using alpha emitters for targeted therapy?

   1. High penetration depth
   2. Low ionizing power
   3. High ionizing power and short range
   4. Long half-life

6. Which of the following is an example of an alpha-emitting radionuclide used in nuclear medicine?

   1. Technetium-99m
   2. Fluorine-18
   3. Radium-223
   4. Iodine-123

7. What is the general formula representing alpha decay of a nucleus $^A_ZX$?

   1. $^A_ZX \rightarrow ^{A-1}_{Z-1}Y + ^1_1H$
   2. $^A_ZX \rightarrow ^{A-4}_{Z-2}Y + ^4_2He$
   3. $^A_ZX \rightarrow ^{A+4}_{Z+2}Y + ^4_2He$
   4. $^A_ZX \rightarrow ^{A}_{Z-1}Y + ^0_{-1}e$