What type of particles does the nucleus of an atom consist of?

The nucleus of an atom consists of protons and neutrons, which are collectively known as nucleons. Protons carry a positive charge, while neutrons are neutral. The presence of these particles within the nucleus is fundamental to the structure of an atom, as they contribute to the atom's mass and stability.

Electrons, while also part of an atom, are located outside the nucleus in various energy levels or shells and do not contribute to the nuclear structure itself. Thus, the correct answer reflects the distinction between the particles that compose the nucleus and those that orbit around it. By understanding that only protons and neutrons make up the nucleus, one gains insight into atomic structure, including the concept of atomic number, which is defined by the number of protons in the nucleus.