definition (1 Viewer)

[strawberry]

can someone gimme a definition of stable isotope??

thanx

 

[Huy]

first off,
for some elements, all isotopes are radioactive, while for others only *one* or *some* isotopes are radioactive.

we talk about radioactive isotopes or radioisotopes rather than radioactive-elements. but the radioactive emission itself comes from the nucleus of the isotope, so we talk about:

* unstable nuclei (ones that are radioactive), and
* stable nuclei (not radioactive)

isotopes of one element have the same atomic number Z (number of protons), but they have different mass numbers (A - the number of protons + neutrons in the nucleus of the species).

isotopes are generally named by their mass number, so you've got rubidium-85, rubidium-87, etc.

having said that,
when you're plotting the number of neutrons against the number of protons in the nucleus of isotopes that are stable, you will find that all the points lie in a narrow band -- the band (or zone) of stability.

you can see what i mean there, but some textbooks will have better explanations/figures.

the converse of a stable isotope are unstable ones,
they are unstable if:
* its atomic number is greater than 83, or
* if its ratio of neutrons to protons puts it OUTSIDE te zone of stability.

so to answer your question,
a stable isotope is not radioactive, and lies in the band of stability, when the neutrons to proton ratio is plotted.

 

[elizabethy]

a satble isotope is one where protons and neutrons are in a low energy level and the nucleus does not emit any kind of radiations