Final answer:
The nucleus of an atom is approximately 100,000 times smaller in diameter than the electron cloud, with the former significantly denser and constituting most of the atom's mass, while the latter occupies the vast majority of the atom's volume.
Step-by-step explanation:
The diameter of the nucleus in an atom is about 100,000 times smaller than the diameter of the electron cloud. While the nucleus, which contains protons and neutrons, is incredibly dense and accounts for 99.97% of an atom's mass, it occupies a minute volume compared to the electron cloud, which encompasses most of the atom's volume. The nucleus is typically on the order of 10-15 meters in diameter, whereas the electron cloud, which defines the outer boundary of the atom, has a diameter on the order of 10-10 meters. A useful metaphor to understand their size difference would be to imagine the nucleus as the size of a blueberry and the atom as large as a football stadium.