The nucleus of an atom contains which types of particles?

The nucleus of an atom is composed of protons and neutrons, collectively known as nucleons. Protons are positively charged particles, while neutrons are neutrally charged and do not have an electric charge. This combination of particles within the nucleus is crucial because they contribute significantly to the atomic mass and also play a key role in defining the identity of the element; the number of protons determines the type of element, while neutrons can vary in number to form different isotopes.

Electrons, on the other hand, are not found in the nucleus; they exist in a cloud surrounding the nucleus, moving in defined energy levels or orbitals. This distinction is important to understand atomic structure and behavior, particularly in chemical reactions and bonding. Therefore, the correct answer accurately reflects the makeup of the atomic nucleus, emphasizing the presence of only protons and neutrons.