Where in an atom is most of the mass concentrated, and where is most of the volume?

1. An atom contains a very small nucleus of protons and neutrons surrounded by a much larger volume containing electrons. 2. The nucleus contains the majority of an atom's mass because protons and neutrons are much heavier than electrons. 3. Electrons occupy almost all of an atom's volume. 4. So mass and volume live in different places, which is the whole point of the nuclear model. _Source: OpenStax Chemistry 2e (CC BY 4.0), Ch 2 'Atoms, Molecules, and Ions', sections 2.1-2.6_