Which of the following best describes the structure of an atom?

The structure of an atom is accurately described as having a nucleus that contains protons and neutrons, with electrons surrounding this nucleus. Protons are positively charged particles, while neutrons are neutral, and together they make up the atomic nucleus, which is where most of the atom's mass is concentrated. Electrons, which have a negative charge, exist in regions around the nucleus known as electron clouds or energy levels, balancing the positive charge of protons and allowing for chemical bonding with other atoms.

This description is fundamental to atomic theory and chemistry, illustrating how the organization of subatomic particles determines an atom's properties and behaviors. By focusing on the prominent roles of protons, neutrons, and electrons, this answer provides a comprehensive view of atomic structure, which is critical for understanding chemical reactions and interactions.