**4. Nuclear stability**

when the number of neutrons (N) and protons (P) are approximately equal it's called stable nuclei. The ratio of N/P is equal one when the elements become heavier, the ratio of neutrons (N) to protons (P) for nuclear stability increases from 1to 1.5. meanwhile the nucleuses has too high (Neutron rich) stability

**Figure 1.** *Nuclear stability diagram.*

decreases at the line of stability See **Figure 1**.If the N/P ratio is too low for stability, the radioactive decay take places in a manner that will be reduce the number of protons and increase the number of neutrons by the net conversion of proton to neutron.
