AAMC FL Practice Exam

In electron capture, where does the electron appear?

1. On the right side

2. In the nucleus

3. On the left side

4. In the cytoplasm

The correct answer is: On the left side

In electron capture, an electron is utilized from the inner shell of an atom (commonly from the K shell) and is absorbed by the nucleus of the atom. This process occurs when a proton in the nucleus combines with the captured electron to form a neutron, which results in the emission of a neutrino. Therefore, the correct understanding is that the electron effectively appears within the nucleus during this process, as it contributes to the transformation of a proton into a neutron. The concept may lead to confusion with the placement of the electron. The appearance of the electron in the nucleus, rather than outside of it or in other cellular structures, highlights that the transaction is fundamentally about nuclear reactions rather than electronic or cellular processes. Such nuances illustrate why having a foundational grasp of atomic structure and nuclear chemistry is pivotal for comprehending processes like electron capture.