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2

I am addressing this part of the question: Also why do only neutrons show fission/fusion and why can't electrons preform fission/fusion? Nuclei with a large number of neutrons are unstable . It so happens for some of them that an extra neutron in a specific low energy range can be caught when impinging on that nucleus , but the resultant new isotope ...


2

There is a lighter nuclide which undergoes fission: $^8Be$. It fissions to two $^4He$ nuclei ($\alpha $ particles) with a lifetime on the order of $10^{-17}$ s. The binding energy per nucleon is much less for the beryllium than for the two $\alpha$s. It's important to note that $^8Be$ is an important link in the triple-alpha fusion process in older stars ...


3

The important argument for this discussion is the Bethe Weizs├Ącker formula, which describes the binding energy of nuclei. I will try to give a cursory overview of the most important aspects. Not only heavy elements show fission and fusion. All elements up to iron-56 (one of the nuclei with the highest binding energy per nucleon) can create energy in ...


8

The mass of a free neutron is 939.566 MeV/c$^2$ (almost 1 GeV/c$^2$, so that's probably where your instructor got the "1" value), and the mass of a free proton is 938.272 MeV/c$^2$. A free neutron will decay into a free proton, free electron ($\beta^-$), and an anti-neutrino, $\bar{\nu}$. The mass of the electron is 0.511 MeV/c$^2$, and of the ...


0

There is no conservation of mass. There is conservation of mass/energy. Proton mass does not equal neutron mass.


3

Deuterium reacts with low energy neutrons to form tritium, though the cross section is very low. Tritium beta decays to $^3$He with a half life of about 12 years, so the process results in very slow production of $^3$He. The trouble is that $^3$He also reacts with low energy neutrons, but it forms tritium and a free proton rather than $^4$He. So the ...


5

An atomic species defined by its number of protons (usually denoted $Z$) and its number of neutrons (usually denoted $N$) is called a nuclide. For atomic species the number of electrons is the same as the number of protons (i.e. $Z$). You are right to assume that the nuclide of a single nuclide solid will typically determine its melting point and hardness ...


2

It's not even that simple, as different crystal structures of a given molecule can have different melting points, e.g. Ice-V . I don't remember enough solid-state physics to state whether any elements form different crystal structures with different melting points, but certainly, for example, the hardness of carbon depends on whether it's diamond or ...


3

Atoms and molecules that have high boiling points and melting points have strong intermolecular bonds that resist form change. Therefore, to make a material win these properties, in general your you want long chained molecules.


1

That particular plot (source) seems to be a plot of the number of neutron captures as a function of energy. Each narrow peak in neutron energy corresponds to the energy of an excited state in the Th-233 or U-239 nucleus --- that is, the target nucleus with an extra neutron. The size of the capture cross section, plus the properties of the decay radiation ...


1

From an energy perspective, a free neutron sees a nucleus as a three-dimensional square well with a depth of a 5--10 MeV. The presence or absence of milli-eV thermal oscillations or eV-scale molecular bonds may change the details of the shape of that potential well, but in general the change is much less important than the uncertainty in the neutron's energy ...



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