Final answer:
Electrons, the negatively charged subatomic particles, are located outside the nucleus of an atom. They occupy orbitals which represent regions of space most likely to be found in, opposed to fixed paths. Protons and neutrons make up the nucleus while most of the atom's space is occupied by the electron's movement.
Step-by-step explanation:
Located outside the nucleus of an atom are negatively charged subatomic particles known as electrons. The nucleus, a positively charged region, contains protons and neutrons that are packed tightly together. In contrast, the region outside the nucleus is primarily empty space where electrons move rapidly in areas called orbitals. These orbitals are not fixed paths like the orbits of planets around the sun, but rather regions of space where electrons are most likely to be found, as described by quantum mechanics.
The comparison of the size of the nucleus and the atom can be quite striking. If the nucleus were the size of a marble, the atom would be approximately the size of a soccer field. This underscores how electrons occupy a vast amount of space relative to the nucleus. In chemical reactions, the interaction of these electrons in their orbitals, including antibonding orbitals, plays a crucial role in the formation and breaking of chemical bonds.