CHEM120 OL, Week 6 Lab

Week 6 Lab: Nuclear Chemistry

Objectives:

· Identify the differences between chemical reactions and nuclear reactions.

· Identify the concept of radioactive decay.

· Identify the nuclear changes associated with alpha, beta or gamma decay.

· Write the products of nuclear reactions involving alpha, beta or gamma emissions.

· Explain the concept of half-lives and complete half-life calculations.

· Identify common subatomic particles and energies involved in nuclear reactions

· Recognize common modes of radioactive decay (alpha, beta, gamma, and electron capture) by observing differences in nucleic mass defect and/or binding energies

· Describe common applications of radioactive isotopes (nuclear medicine, radiometric/carbon dating, nuclear energy)

· Describe how carbon dating works

Radioactivity is something that only happens in nuclear power plants, right?

In this simulation, you will learn that radioactivity is much more common than you might think—in fact, you are surrounded by it! You will also learn what types of atoms are radioactive and why, and how alpha, beta, and gamma decay generate different types of radioactivity.

Understand the processes happening in the atomic nucleus

Use our holofloor to visualize how protons and neutrons interact in the nucleus. Experiment with stability of isotopes and figure out why some combinations are more stable than others.

Analyze properties of alpha, beta, and gamma decay

Radioactive isotopes can undergo alpha, beta, and gamma decay. Each of these processes generates radioactivity; luckily, we are in a virtual simulation and we can experiment with these isotopes without being exposed to harmful levels of radiation. Additionally, you will be able to see how protons and neutrons interact in the nucleus thanks to our advanced holofloor.

Not all atoms are stable. When atoms are born in a nuclear reactor, whether it be the heart of a star or a power plant, a portion of them are radioactive and are referred to as radioisotopes. These radioisotopes break down over time, releasing energy and transforming into more stable forms in processes known as radioactive decay.

Part 1: Complete Labster lab: Nuclear Chemistry

1. Purpose: Describe in complete sentences and in your own words, the purpose of this experiment.

2. Observations: Record three observations from the simulation.

I.

II.

III.

3. Complete the table below

4. In the space below, use X for the symbol of an element, Z for the atomic number and A for the mass number to write a general nuclide symbol.

5. An isotope of strontium has 38 protons and 52 neutrons. What is the nuclide symbol for an atom of this isotope?

6. Write the nuclear equation for the gamma decay of fluorine-19.

7. Write the nuclear equation for the positron emission of sodium-23.

8. Suppose Potassium-41 undergoes electron capture. Write the nuclear equation that represents this process.

Part 2: Half-life and medical imaging
Technetium-99m is an important isotope used in medical imaging (the m stands for metastable). Each day healthcare professionals around the world use Technetium-99m in thousands of medical scans. This material has a very short half-life of about 6 hours and decays by gamma decay to Technetium-99. In this exercise, you will look at why half-life is an important concern and how it affects your health.

9. Technetium-99m has a half-life of 6 hours. Use this to answer the following questions:

a. What percentage of Technituum-99m would remain in your body 24 hours after injection with this radioisotope? Assume that the initial percentage is 100%.

b. In terms of radiation exposure, why is this short half-life beneficial?

10. Due to the short half-life of Technetium-99m, this material cannot be easily transported. However, Technetium-99m can be formed from the beta decay of Molybdenum-99, which has a half-life of about 2.75 days. Unfortunately, the world’s supply of molybdenum-99 is in jeopardy as the nuclear facilities that produce this material are beginning to cease operations. Use this information to answer the following questions:

a. Write the nuclear equation for the beta decay of Molybdenum-99.

b. If you have 50 grams of Molybdenum-99, how many grams will remain after 11 days?

c. Would a good solution to the coming shortage of Molybdenum-99 be for hospitals to stockpile large amounts of Molybdenum-99? Why or why not?

Reflection: Choose any medical isotope besides the ones mentioned in exploration 2 and report on the uses, half-life, decay type(s), and any safety concerns.

Be sure to cite your sources fully.

Grading Rubric:

5