CHEM 120 Week 6 Lab: Nuclear Chemistry

CHEM 120 Week 6 Lab: Nuclear Chemistry

CHEM 120 Week 6 Lab: Nuclear Chemistry

Name

Chamberlain University

CHEM-120 Intro to General, Organic & Biological Chemistry

Prof. Name

Date

Week 6 Lab: Nuclear Chemistry

Objectives

The purpose of this lab is to explore nuclear chemistry and understand its key concepts. By the end of the lab, students should be able to:

  • Identify the differences between chemical reactions and nuclear reactions.

  • Understand radioactive decay and the nuclear changes associated with alpha, beta, and gamma emissions.

  • Write nuclear reactions involving alpha, beta, or gamma decay.

  • Explain half-lives and perform related calculations.

  • Identify subatomic particles and energies in nuclear reactions.

  • Recognize modes of radioactive decay (alpha, beta, gamma, electron capture) through nuclear mass defect and binding energy.

  • Describe applications of radioactive isotopes, such as nuclear medicine, carbon dating, and nuclear energy.

  • Understand how carbon dating works.

Radioactivity is not limited to nuclear power plants; in fact, it occurs naturally and surrounds us daily. In this lab simulation, students will explore the atomic nucleus and learn why some isotopes are stable while others are not. By experimenting with alpha, beta, and gamma decay in a virtual environment, students can observe the mechanisms of radioactivity safely.

Part 1: Labster Lab – Nuclear Chemistry

Purpose

The purpose of this experiment was to identify the subatomic particles and energies involved in nuclear reactions, understand the concept of half-life, recognize the modes of radioactive decay, explore how carbon dating works, and investigate applications of radioactive isotopes.

Observations

Three observations from the simulation included:

  1. Equal charges repel each other.

  2. The nuclear force acts over a very small distance, occurring only within the nucleus.

  3. Half-life is used to estimate when a specific atom will decay.

Radiation Types and Their Effects

Radiation Type Effect on Atomic Number Effect on Protons Effect on Mass Number
Alpha particle Decreases by 2 Decreases by 2 Decreases by 4
Beta particle Increases by 1 Increases by 1 No change
Gamma particle No change No change No change
Positron Decreases by 1 Decreases by 1 No change
Electron capture Decreases by 1 Decreases by 1 No change

General Nuclide Symbol

The general nuclide symbol is written as:

A
X
Z

Example: Strontium Isotope

  • Number of protons = 38

  • Number of neutrons = 52

  • Mass number = 38 + 52 = 90

  • Atomic number = 38

  • From the periodic table, the element is Strontium (Sr).

  • Nuclide symbol = ⁹⁰Sr₃₈

Nuclear Equations

  1. Gamma decay of fluorine-19:
    ¹⁹F → ¹⁹F + γ

  2. Positron emission of sodium-23:
    ²³Na → ²³Ne + e⁺

  3. Electron capture of potassium-41:
    ⁴¹K + e⁻ → ⁴¹Ar

Part 2: Half-Life and Medical Imaging

Technetium-99m is widely used in medical imaging. It has a short half-life of 6 hours and undergoes gamma decay to form Technetium-99.

Question 9

a. What percentage of Technetium-99m would remain in your body 24 hours after injection?
After four half-lives (24 ÷ 6), only 6.25% of the isotope would remain.

b. Why is the short half-life beneficial?
The short half-life is beneficial because it reduces long-term radiation exposure, minimizing harmful side effects such as dizziness, chest pain, or irregular heartbeat.

Question 10

a. Write the nuclear equation for the beta decay of Molybdenum-99.
⁹⁹Mo → ⁹⁹mTc + β⁻

b. If you have 50 grams of Molybdenum-99, how many grams will remain after 11 days?
Using half-life calculations, approximately 3.12 g of Molybdenum-99 would remain.

c. Would stockpiling Molybdenum-99 solve the shortage issue? Why or why not?
No, stockpiling is not effective due to the short half-life and instability of Mo-99. It must be continuously produced to ensure reliable medical imaging supplies.

Reflection

Iodine-131 is another medical isotope used for both treatment and diagnosis of thyroid cancer. It is typically administered as a capsule or liquid. Its half-life is 8.06 days, and it decays by both beta and gamma radiation.

While effective in therapy, exposure to large amounts of Iodine-131 can cause health risks. External exposure may lead to skin and eye burns, while internal exposure can damage the thyroid gland. Because the thyroid cannot distinguish between stable and radioactive iodine, absorbed I-131 increases the risk of thyroid cancer.

References

Centers for Disease Control and Prevention. (2018, April 4). CDC radiation emergencies: Iodine-131. U.S. Department of Health and Human Services. Retrieved October 3, 2022, from https://www.cdc.gov/nceh/radiation/emergencies/isotopes/iodine.htm

CHEM 120 Week 6 Lab: Nuclear Chemistry