Question

This is for a study guide for my semester final, and I have no clue how to answer this, please help, and please at least try to help!

Besides the major types of radioactive decay, there are two others: positron emission and electron capture.
• Compare and contrast positrons with electrons.
• Explain how positron emission works and how it causes transmutations.
• Explain how electron capture works and how it causes transmutations.
• Compare the transmutations caused by positron emissions and electron capture.

Answer 1

Positron emission = emission of a positron and a neutrino when a proton is convert into a neutron. The total number of particles in the nucleus doesn't change, -1 proton +1 neutron

It's a spontaneous reaction for some nucleus.

eg:

Positron = e+

Neutrino=ve

O-15 --> N-15 + e+ +ve

Electron capture= A nucleus absorb an electron while a proton is convert in a neutron and emit a neutrino. The total number of particles in the nucleus doesn't change, -1 proton +1 neutron

eg:

Al-26 +e- --> Mg-26 + ve

Electron capture and positron emission are two mechanisms to explain the decay of some unstable isotopes. Electron capture is usually observed when the energy difference between the initial and final state is low. Mainly because of the larger amount of kinetic energy need for the expulsion two particles with the positron emission mechanism.