What characterizes an isomeric transition?

An isomeric transition is characterized by a change in energy state of a nucleus without any alteration in either the atomic number or mass number. This transition typically occurs when an excited nuclear state returns to a lower energy state, releasing energy in the form of gamma radiation.

In this process, the atomic number remains constant, as it is determined by the number of protons in the nucleus, and the mass number also stays the same, being the sum of protons and neutrons. The nucleus transitions from a higher energy isomer state to a more stable configuration, which is why "change in energy state" is crucial to understanding isomeric transitions.