Problem: Which nuclide in each pair would you expect to have the longer half-life?Cs-113 or Cs-125

FREE Expert Solution

We’re asked to determine which nuclide in the given pair is expected to have the longer half-life (more stable)


Recall that the stability of a nuclide (longer half-life) depends on the number of protons and neutrons:

  • If neutron-to-proton ratio is ~ 1  stable 
    • Nuclides with even numbers of both protons and neutrons are generally stable 
  • If neutron-to-proton ratio is less than or greater than 1 → unstable

Recall that: 


Atomic number, Z = # of protons = # of electrons

Atomic mass, A = # of neutrons + # of protons 

**also known as mass number (number beside an isotope)


For the given pair: Cs-113 and Cs-125

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Problem Details

Which nuclide in each pair would you expect to have the longer half-life?

Cs-113 or Cs-125

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.