Electrons, protons, and atoms have different sizes, and their scales can be described as follows:
Electron: An electron is a subatomic particle with a negative electric charge. Electrons are considered point-like particles in the sense that they are elementary particles with no known internal structure or size. In terms of their physical size, electrons are considered to be point particles, meaning they do not have a measurable size or extent.
Atom: Atoms are the basic building blocks of matter. They consist of a central nucleus, which contains protons and neutrons, surrounded by a cloud of electrons. The size of an atom can be described by its atomic radius, which represents the average distance between the nucleus and the outermost electron shell. Atomic radii vary depending on the element, but they are typically on the order of angstroms (10^(-10) meters). For example, the approximate atomic radius of a hydrogen atom is about 0.1 nanometers (1 angstrom).
Proton: Protons are subatomic particles found within the nucleus of an atom. They have a positive electric charge, equal in magnitude to that of an electron but opposite in sign. Protons have a finite size and are composed of even smaller particles called quarks. The size of a proton can be described in terms of its root-mean-square (rms) charge radius, which is a measure of the distribution of the charge within the proton. The currently accepted value for the proton's rms charge radius is approximately 0.88 femtometers (10^(-15) meters).
Comparing the sizes, the atomic radius of an atom is typically several orders of magnitude larger than the size of an electron, while the proton's size is on a similar scale as the atomic radius. However, it's important to note that the sizes mentioned here are averages or measures of distribution, and the actual particles involved have quantum mechanical properties that can be difficult to precisely define in terms of classical notions of size.