Which subatomic particle is neutral and exists in the nucleus of an atom?

The neutron is the subatomic particle that is neutral, meaning it does not carry a positive or negative charge. Neutrons are found in the nucleus of an atom, along with protons, which are positively charged. The presence of neutrons in the nucleus contributes to the mass of an atom but does not affect its overall electrical charge.

The significance of neutrons lies in their role in stabilizing the nucleus; they help balance the repulsive forces between positively charged protons. This balance is essential for the stability of atoms, as an imbalance can lead to radioactive decay.

In contrast, protons are positively charged, electrons are negatively charged and orbit the nucleus, and positrons are the antiparticles of electrons, carrying a positive charge. Understanding the role of neutrons and their neutral charge is fundamental in nuclear physics and chemistry, particularly in the context of atomic structure and stability.