Isotopes: Proton vs Neutron Counts

In summary, the stability of an isotope is determined by the number of protons it has compared to the number of neutrons. The only stable isotope is He-3, with more protons than neutrons.
  • #1
Colin Cheng
13
0
I'm in year 10 and I have been studying physics and chemistry. When I learned isotopes, I notice that for isotopes, the number of neutron is always higher than that of proton. Is it possible that there are isotopes that the number of neutron is lower than that of proton? If no, is that because repulsion will take place if the number of neutron is lower than that of proton thus making the nucleus easy to spilt up? If I said something wrong or non-sense, please forgive me.
 
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  • #2
Yes. H1 has one proton and zero neutrons. :smile:
 
  • #3
Also He3, two protons and one neutron. Notice that it is stable in contrast to H3, one proton and two neutrons.

There are others, but they tend to be unstable.
http://atom.kaeri.re.kr/ton/
 
  • #4
Colin Cheng said:
I'm in year 10 and I have been studying physics and chemistry. When I learned isotopes, I notice that for isotopes, the number of neutron is always higher than that of proton. Is it possible that there are isotopes that the number of neutron is lower than that of proton? If no, is that because repulsion will take place if the number of neutron is lower than that of proton thus making the nucleus easy to spilt up? If I said something wrong or non-sense, please forgive me.
One can look at nuclides (isotopes) and their properties here -
http://www.nndc.bnl.gov/chart/

He-3 is the only stable isotope with more protons than neutrons. Essentially, stability requires the same number or greater number of neutrons than protons, with some limits. When the number of protons exceeds the neutrons, then electron capture or positron emission generally is the decay mode.
 
  • #5
Astronuc said:
One can look at nuclides (isotopes) and their properties here -
http://www.nndc.bnl.gov/chart/

He-3 is the only stable isotope with more protons than neutrons.
And the other is proton.
Astronuc said:
Essentially, stability requires the same number or greater number of neutrons than protons, with some limits. When the number of protons exceeds the neutrons, then electron capture or positron emission generally is the decay mode.

Look at the simple cases of 1 excess protons:
Proton: Stable. Neutron undergoes beta decay, releasing 782 keV and half-life 10 minutes
He-3: Stable. Triton undergoes beta decay... but releases only 18 keV, with half-life 12 years. Another consequence of neutron having bigger binding energy in T that a proton has in He-3 is that He-3 easily captures slow neutrons, expelling a proton and releasing energy.
Li-5: no set of 5 nucleons is bound.
Be-7: bound but unstable. Unlike n (beta decay 782 keV) and t (beta decay 18 keV), Li-7 is stable to beta decay, instead Be-7 captures an electron releasing 862 keV, with half-life 53 days. Note that Be-7 cannot emit a positron, because electron capture releases just 862 keV, and creation of electron-positron pair would take 1022 keV
B-9: unbound (unlike Be-9, which is bound and stable)
C-11: would release 1982 keV on electron capture, therefore can also emit a positron with 960 keV left over, and does so, with half-live 20 minutes.
 

1. What is an isotope?

An isotope is a form of an element that has the same number of protons in its nucleus, but a different number of neutrons. This means that isotopes have the same atomic number, but a different atomic mass.

2. How are isotopes different from each other?

Isotopes differ from each other in terms of their atomic mass, which is determined by the number of neutrons in their nucleus. This can affect the stability and chemical properties of the element.

3. What is the difference between proton and neutron counts in isotopes?

Protons and neutrons are both subatomic particles found in the nucleus of an atom. Protons have a positive charge, while neutrons have no charge. In isotopes, the number of protons remains the same, but the number of neutrons can vary, resulting in different isotopes of the same element.

4. How do isotopes affect the behavior of an element?

The different neutron counts in isotopes can affect the stability and reactivity of an element. Isotopes with more neutrons tend to be less stable and can undergo radioactive decay, while isotopes with fewer neutrons may be more stable and less likely to undergo chemical reactions.

5. What are some practical applications of studying isotopes?

Studying isotopes can provide valuable information about the history and composition of different materials. It is also used in fields such as nuclear medicine, environmental science, and archaeology. Isotopes can also be used as tracers to track the movement of substances in chemical reactions and biological processes.

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