I am not getting the same answer in a nuclear decay problem

[Previous Community Member]

My sons and I are working through a chemistry textbook.  We all three keep getting a different answer from the teacher guide.

Gd 146/64 decays into e- and what? My sons and I keep getting Tb 146, but the teacher guide says Eu 146. Isn't this an example of beta decay, where a neutron becomes a proton?

Thank you,

Dawn

[mpfailey]

Gadolinium-146 is a neutron deficient radionuclide that decays by electron capture. This changes the atomic number by decreasing Z by 1. The mass number, A, stays the same. The radioisotope thus changes to Europium-146.

The decay mechanisms is not a beta minus decay (e-) but an electron capture decay.

The teacher's guide is correct.