Where is most of an atoms mass locted?

In the nucleus because both protons and neutrons have mass and are located there.

Electrons have nearly no mass at all and are found outside of the nucleus.

Most of an atom's mass is located in its nucleus. The nucleus is composed of protons and neutrons, which are collectively known as nucleons. These subatomic particles are tightly packed together in the center of the atom. The protons have a positive charge, while the neutrons have no charge. Electrons, which are negatively charged, are found in the electron cloud surrounding the nucleus, but they have a much smaller mass compared to protons and neutrons. Therefore, when considering the mass of an atom, the bulk of it is concentrated within the nucleus.

To determine the location of most of an atom's mass, you need to understand the basic structure of an atom, consisting of protons, neutrons, and electrons. This knowledge can be gained through studying atomic theory or taking courses in chemistry or physics. Additionally, modern scientific tools like particle accelerators and detectors are used to probe atoms and provide experimental evidence for their structure. By analyzing the results of these experiments and understanding the principles of atomic theory, scientists have been able to determine the location of an atom's mass.