Problem: Write a nuclear equation for the most likely mode of decay for each of the following unstable nuclides.Th-221

FREE Expert Solution

We’re being asked to write a nuclear equation for the most likely mode of decay of Th-221.


We will do the following steps to solve this problem:

Step 1: Determine the mode of decay

Step 2: Write the nuclear equation


Recall that the stability of an isotope depends on the ratio of neutrons to protons (N/Z). This means for stable isotopes with:

• Z ≤ 20; the N/Z ratio should be equal to 1.0

• 20 < Z ≤ 40; the N/Z ratio should be equal to 1.25

• 40 < Z ≤ 80; the N/Z ratio should be equal to 1.50

• Z < 83; the stable nuclide does not exist


The N/Z values for stable isotopes form the valley or band of stability:


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This means for isotopes:

• above the valley of stability: there too many neutrons in the isotope

            Mode of decay: Either beta decay (0–1β) or neutron emission (10n; not in the choices)

• below the valley of stability: there too many protons in the isotope

            Mode of decay: Either positron emission (01e) or electron capture (0–1e)

• with atomic mass ≥ 200 amu: there too many protons and neutrons in the isotope

            Mode of decay: alpha decay (42α)



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Problem Details

Write a nuclear equation for the most likely mode of decay for each of the following unstable nuclides.

Th-221

Frequently Asked Questions

What scientific concept do you need to know in order to solve this problem?

Our tutors have indicated that to solve this problem you will need to apply the Band of Stability concept. You can view video lessons to learn Band of Stability. Or if you need more Band of Stability practice, you can also practice Band of Stability practice problems.