When we consider the space between particles such as protons, neutrons, and electrons, it is important to note that the concept of "nothingness" or "emptiness" can be somewhat misleading in the context of quantum physics.
According to quantum field theory, the vacuum is not truly empty but rather a state filled with quantum fields and fluctuations. These fields permeate all of space and can have temporary fluctuations that give rise to the creation and annihilation of particle-antiparticle pairs.
In terms of the space between particles within an atom, such as the space between the atomic nucleus (composed of protons and neutrons) and the electrons, it is indeed relatively vast compared to the sizes of the particles themselves. However, this space is not devoid of anything. It is occupied by electron orbitals, which represent the probability distributions of finding electrons around the nucleus. These orbitals describe the regions where electrons are likely to be found, and they fill up space within the atom.
As for the space within quarks, it's important to note that quarks are elementary particles and do not have a known internal structure. They are considered point-like particles with no size or internal substructure. The concept of "empty space" within a quark doesn't apply in the same way as it does for composite particles like atoms.
In summary, while there may be relatively large spaces between particles in terms of their sizes, those spaces are not empty but filled with quantum fields, probability distributions, and potential fluctuations. The precise percentage of "nothingness" is not well-defined or quantifiable in this context. The nature of space and its constituents, as described by quantum field theory, is a complex and active area of research in theoretical physics.