Which part of the atom contains protons and neutrons?

The nucleus of an atom is the central part where protons and neutrons are located. Protons are positively charged particles, while neutrons carry no charge. Together, they make up the bulk of the atom's mass and determine the atomic number and isotopes of an element.

The electron cloud, in contrast, is where the electrons are found, surrounding the nucleus and defining the size of the atom. The inner and outer shells refer specifically to the layers of electrons around the nucleus rather than the particles that make up the nucleus itself. The focus on the nucleus as the location for protons and neutrons is critical for understanding atomic structure and reactions, as well as how elements are classified in the periodic table.