Predict the mode of decay for Mn-59.
a. beta decay <--
b. positron emission
c. electron capture
d. Mn-59 is stable
I was wondering how it was a. and not the others through an explanation? Thanks!
This you tube has a rather good explanation.
https://www.youtube.com/watch?v=G_83ES6ceo4
N = 34 and Z = 25 and N/Z = about 1.36. For elements in the 20-40 Z you want N/Z to be 1.25 so we need to convert neutrons to protons which means emission of a beta particle.
The mode of decay for Mn-59 is beta decay.
In beta decay, a neutron in the nucleus of an atom is converted into a proton, and an electron (beta particle) is emitted from the nucleus. This process changes the atomic number of the nucleus, resulting in the formation of a new element.
Mn-59 has 25 protons and 34 neutrons. In beta decay, one of the neutrons in Mn-59 is converted into a proton, resulting in the formation of a new element with 26 protons. Therefore, the mode of decay for Mn-59 is beta decay (option a).
Option b, positron emission, is not applicable to Mn-59 because it involves the conversion of a proton into a neutron, which would decrease the atomic number of the nucleus.
Option c, electron capture, involves the capture of an electron by a proton in the nucleus, resulting in the conversion of a proton into a neutron. This process also decreases the atomic number of the nucleus, which is not observed in the decay of Mn-59.
Option d, Mn-59 is stable, is incorrect because Mn-59 is not a stable nuclide. It undergoes decay over time, and as mentioned earlier, it primarily undergoes beta decay.
To determine the mode of decay for Mn-59, we can look at the number of protons and neutrons in its nucleus.
Mn-59 has 25 protons and 34 neutrons. Ideally, stable isotopes have a balanced number of protons and neutrons. Thus, we can see that Mn-59 has an imbalance between the two.
Now, let's consider the options:
a. Beta decay: In beta decay, a neutron in the nucleus is converted into a proton, and a high-energy electron called a beta particle is emitted. This process helps to bring the neutron-to-proton ratio closer to stability. Since Mn-59 has an excess number of neutrons, it can undergo beta decay to convert one of its neutrons into a proton, resulting in a more stable nucleus.
b. Positron emission: Positron emission occurs when a proton in the nucleus is converted into a neutron, and a positron (a positively charged electron) is emitted. This process helps in cases where there is an excess of protons. However, since Mn-59 has an excess number of neutrons, positron emission is not the correct mode of decay.
c. Electron capture: Electron capture happens when an electron from the inner orbital is captured by a proton in the nucleus, forming a neutron and a neutrino. This process also helps in cases where there is an excess of protons. However, since Mn-59 has an excess number of neutrons, electron capture is not the correct mode of decay.
d. Mn-59 is stable: This statement is incorrect since we have already established that Mn-59 has an imbalance between the number of protons and neutrons.
Based on the information provided, the correct mode of decay for Mn-59 is beta decay (option a) since it helps adjust the neutron-to-proton ratio and move closer to a more stable configuration.