One type of commercial smoke detector contains a minute amount of radioactive am

Question

One type of commercial smoke detector contains a minute amount of radioactive americium-241 (241Am), which decays by alpha-particle production. The alpha-particles ionize molecules in the air, allowing it to conduct an electric current. When smoke particles enter, the conductivity of the air changes and the alarm buzzes.

The complete decay of 241Am involves successive alpha, alpha, beta, alpha alpha, beta, alpha, alpha, alpha, beta, alpha and beta production. Identify the 11 intermediate nuclides.
What is the final stable nucleus produced in this decay series?

Explanation / Answer

By losing an alpha particle, you lose the equivalent of a helium nucleus (two protons and two neutrons), therefore losing two atomic numbers and four nucleon numbers. A beta particle changes a neutron to a proton, therefore gaining an atomic number with no change in total nucleon number.

Here is the complete series, in order of particle loss you listed:

Am-241 -> Np-237 -> Pa-233 -> U-233 -> Th-229 -> Ra-225 -> Ac-225 -> Fr-221 -> At-217 -> Bi-213 -> Po-213 -> Pb-209 -> Bi-209 (stable)

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