91Ó°ÊÓ

In positron emission, a proton within an unstable atomic nucleus is converted into a neutron. During this process, a positron (which is an anti-particle of an electron) and a neutrino are emitted from the nucleus. This results in the decrease of the atomic number (Z) by 1, while the mass number (A) remains the same.

Electron capture is another process in which an unstable nucleus can reach a more stable state. In this case, a proton within the nucleus captures an electron, usually from the innermost electron shell (K-shell). The proton is then converted into a neutron, and a neutrino is emitted. As with positron emission, the atomic number (Z) decreases by 1, while the mass number (A) remains the same.

Both positron emission and electron capture are methods through which an atomic nucleus with too many protons can become more stable, and they both result in a decrease of the atomic number by 1. However, there are differences between these two processes: 1. Process: In positron emission, a proton is converted into a neutron and a positron is emitted from the nucleus. In electron capture, a proton captures an electron and is converted into a neutron. This converstion takes place within the nucleus, and no positrons are released from the nucleus. 2. Emitted particles: In positron emission, a positron and a neutrino are emitted from the nucleus, while in electron capture, only a neutrino is emitted after the conversion of a proton into a neutron. 3. External electrons: Electron capture involves interaction between a proton in the nucleus and an electron from the atom's electron shell. On the other hand, positron emission does not involve any interactions with the atom's electrons. By understanding the difference between positron emission and electron capture, we can better comprehend the ways in which unstable atomic nuclei can reach more stable configurations.