Nuclear binding energy Only under conditions of extreme pressure and temperature (for example, within the core of a star), can such a process take place. There are around 94 naturally occurring elements on earth. The atoms of each element have a nucleus containing a specific number of protons (always the same number for a given element), and some number of neutrons, which is often roughly a similar number. Two atoms of the same element having different numbers of neutrons are known as isotopes of the element. Different isotopes may have different properties - for example one might be stable and another might be
Avoided crossing one set of parameters. If both of the atoms of a diatomic molecule is same, the symmetry suggests that different configurations keeping their mutual distance fixed will result into same electronic states. So it is the relative distance formula_73 which acts as a parameter for the two equations promising level crossing. Hence due to the avoided crossing theorem in general we can not have level crossings between two electronic states of same symmetry. But in polyatomic molecules the number of independent mutual distances of nuclei are more. For a N-atomic molecule the number of independent mutual separation is formula_74 (for