Elements with the same number of protons and neutrons are considered what?

Elements with the same number of protons and neutrons are considered stable because these configurations generally correspond to a balanced nuclear structure. In a stable nucleus, the forces holding the protons and neutrons together (the strong nuclear force) are effectively counterbalancing the repulsive forces among the positively charged protons. When an atom has an equal number of protons and neutrons, it tends to have a strong enough binding energy that contributes to its stability, allowing it to exist without undergoing radioactive decay.

As a result, such elements are less likely to emit radiation and are usually found in nature without any significant changes over time, distinguishing them from unstable or radioactive isotopes which have an imbalance in their neutron-to-proton ratio leading to instability and decay. The idea of being "heavy" usually refers to nuclides with a larger number of nucleons overall, while "unstable" and "radioactive" are terms that imply an active decay process, neither of which is a characteristic of stable elements with equal numbers of protons and neutrons.