# Nuclear stability

## Nuclear stability

Nuclear stability means nucleus does not spontaneously emit any kind of radioactivity (radiation). On the other hand, if the nucleus is unstable (not stable), it has the tendency of emitting some kind of radiation, i.e., it is radioactive. Therefore the radioactivity is associated with unstable nucleus-Stable nucleus ----- non-radioactive

Unstable nucleus ----- radioactive

There is no any theory to explain the nuclear stability, but there are only general observations based on the available stable isotopes. It appears that neutron to proton (n/p) ratio is the dominant factor in nuclear stability. The nucleide having n to p ratio (i.e. n/p) is one are stable and if the n to p ratio deviates from one are unstable. This ratio is close to 1 for atoms of elements with low atomic number and increases as the atomic number increases. One of the simplest ways of predicting the nuclear stability is based on whether nucleus contains odd/even number of protons and neutrons-

1. Nuclides containing odd numbers of both protons and neutrons are the least stable means more radioactive.

2. Nuclides containing even numbers of both protons and neutrons are most stable means less radioactive.

3. Nuclides contain odd numbers of protons and even numbers of neutrons are less stable than nuclides containing even numbers of protons and odd numbers of neutrons.

In general, nuclear stability is greater for nuclides containing even numbers of protons and neutrons or both. The stability of nuclei of different mass number and the same mass number can be explained on the basis of binding energy per nucleon.

## Nuclear Binding Energy

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