Which subatomic particle contributes to the nuclear mass and stability of an atom without carrying a charge?

Neutrons are the subatomic particles that contribute to both the nuclear mass and the stability of an atom while remaining electrically neutral, meaning they do not carry a charge. Their presence in the nucleus helps to bind protons together. Since protons are positively charged, they repel each other due to electromagnetic forces; however, neutrons, lacking charge, do not contribute to this repulsion. Instead, they add to the overall mass of the nucleus and play a critical role in stabilizing it.

Additionally, a stable nucleus typically contains a specific ratio of protons to neutrons; too few or too many neutrons can lead to instability, resulting in radioactive decay. Thus, neutrons are essential for the stability of many isotopes of elements, influencing their behavior in chemical reactions and physical processes. In contrast, electrons are involved in chemical bonding and reactions but do not contribute to nuclear mass. Protons do carry a positive charge and contribute to mass, but their presence alone would lead to nuclear instability without neutrons. Isotopes refer to variations of an element based on neutron count but do not specifically identify a type of particle.