Chapter 10 Question

Question

Actinium-225 undergoes alpha decay.

a). Write the corresponding nuclear equation.

b). The daughter formed in part (a) undergoes in its turn beta decay. Write the equation.

Answer 1

An alpha particle is a helium nucleus. So when an alpha particle is on of the fission product, the atomic number (# of protons) in the parent nucleotide decrease by 2 and the mass number decreases by 4.

So, with Ac-225 the following would be the nuclear equation:

89-Ac-225 → 87-Fr-221 + 2-He-4

Abeta decay involves the ejection of an electron (the beta particle). This electron comes from the nucleus as a neutron (which is, essentially, a proton/electron pair). Since the beta particle is of negligible mass, the mass of the daughter isotope doesn't change, but the new proton increases the atomic number by 1.

So, 87-Fr-211 → 88-Ra-211 + e^-