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The nucleus contains protons and neutrons, positive and neutral particles. The positive protons are trying to repel each other and the neutrons provide a 'buffering' that holds the nucleus together (called binding energy), some theories say this involves the continuous exchange of quarks, that allows the protons to stay close to each other in the nucleus. Larger nuclei have a different problem, the nucleus is large enough that different regions, like the extreme top and the extreme bottom repel and can cause the atom to expel particles. This is radioactive decay. One scientist (George Gamow?) came up with a theory of constantly moving nuclei that, instead of being a static spherical nucleus, would act like a liquid drop that is undulating and the constant movement and change of shape could cause deformation to a point that the repulsion of opposite sides of the nucleus would cause the decay.

Short answer -- all those positive protons in a large nucleus just don't 'like' being that close to each other.

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11y ago
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12y ago

If the outer shell of the nucleus is full of electrons then it is stable. In the first shell you are allowed 2 electrons after that you are allowed 8 electrons. If the out most shell does not have the full amount of electrons in it it is unstable.

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15y ago

An Unstable Isotope is a radioactive isotope. Unstable Isotopes emit radioactivity as they break down overtime.

Stable isotopes remain constant.

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Q: Why are some isotopes stable and others are not stable?
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Related questions

Why is it that some isotopes of an element are able to exist indefinitely?

Some isotypes are more stable than others. Decay occurs because of instability in isotopes, so stable isotopes do not undergo radioactive decay.

What is stable and unstable isotopes?

Stable isotopes are isotopes that do not undergo radioactive decay and have constant atomic mass. Unstable isotopes, also known as radioactive isotopes, decay over time by emitting radiation.

What are some of golds isotopes?

Gold has only one stable isotope, all others are radioactive.

Does argon have isotopes?

yes, all elements have isotopes. some stable, some radioactive.

Are iron elements stable?

Iron is an element, and there is only one element called iron (Fe). There are no iron element(s), but if you mean isotopes, then some iron isotopes are stable, and some aren't. No known element is stable in of it's isotopes.

Does radioactive isotopes have a stable nuclei?

Radioactive isotopes are not stable.

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Stable isotopes are used as tracers.

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copper has 2 stable isotopes

What isotopes are stable?

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Are most isotopes stable?

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What is the stable nucleus produced at the end of the decay steps in a uranium decay series?

Thorium, radium, radon, polonium, thallium, etc.

Tin has the most stable isotopes of any element How many stable isotopes does it have?

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