How could I tell if an element is stable or unstable? One of the examples is 89/42 Mo

The only rule I know entirely is that if the atomic number is greater then 83 then it is unstable.

Thanks

http://chemwiki.ucdavis.edu/Physical_Chemistry/Nuclear_Chemistry/Nuclear_Stability_and_Magic_Numbers

To determine if an element is stable or unstable, you can consider a few factors.

1. Atomic Number: As you mentioned, if the atomic number (number of protons) is greater than 83, the element is generally considered unstable. This is because elements with higher atomic numbers tend to have more protons than neutrons, leading to an imbalance in the nucleus and the potential for instability.

2. Neutron-to-Proton Ratio: The stability of an element can also be influenced by the neutron-to-proton ratio (N/Z ratio) in its nucleus. For lighter elements, a roughly equal number of protons and neutrons (N/Z ~ 1) often indicates stability. However, for heavier elements, a higher number of neutrons (N/Z > 1) may be required to stabilize the nucleus.

Let's specifically consider the example you mentioned, 89/42 Mo.

The atomic number of molybdenum is 42, which is less than 83, so it does not automatically qualify as unstable based on the first rule.

To determine if the isotopic form 89/42 Mo is stable, you would need to consider its neutron-to-proton ratio.

In this case, molybdenum has 47 neutrons (89 - 42 = 47). Since the N/Z ratio is approximately 47/42 (or 1.12), it falls within the range that is typically considered stable, especially for lighter elements.

Therefore, based on these factors, the isotopic form 89/42 Mo is likely stable.

To determine whether an element is stable or unstable, you can consider a few factors. One of the main factors is the atomic number of the element, which represents the number of protons in the nucleus.

As you mentioned, if the atomic number is greater than 83, the element is generally considered unstable. This is because elements with atomic numbers higher than 83 have an excessive number of protons, leading to an imbalance between the strong electromagnetic forces pushing the protons apart and the strong nuclear forces holding them together. As a result, these elements are radioactive and undergo spontaneous radioactive decay.

In the example you provided (89/42 Mo), the atomic number of 42 falls below 83, indicating that it is not inherently unstable based on this rule. However, determining the stability of an element requires more analysis.

Apart from the atomic number, you also need to consider the neutron-to-proton ratio. This ratio depends on the isotope of the element, which is determined by the number of neutrons in the nucleus. The stability of an element is influenced by having the right balance between neutrons and protons.

In general, stable isotopes tend to have a roughly equal number of neutrons and protons or have a slight excess of neutrons. However, the specific stability of isotopes can vary. Some elements have only stable isotopes, while others have both stable and unstable (radioactive) isotopes.

To determine the stability of a specific isotope, you need to consult the periodic table or other reliable sources. For example, for the isotope 89/42 Mo, you can check a periodic table or nuclear data tables to identify whether this isotope is stable or unstable.

In summary, while the rule you mentioned about atomic numbers above 83 indicating instability is true, the stability of an element or isotope is also affected by the ratio of neutrons to protons. Therefore, it is necessary to consider both the atomic number and the isotopic composition of the element to accurately determine its stability.