Are protons and neutrons smaller than electrons?
Electrons are actually much smaller than protons and neutrons.
Protons and neutrons have masses which are equal to 1 atomic mass unit. Technically they vary from each other slightly, but most classroom applications don't require you to use this information.
The mass of an electron is about 1/1800 the mass of a proton. This is why the mass of electrons is ignored when you are determining the mass of an atom.
Your question is interesting in that another interpretation is possible. The volume occupied by the nucleus (protons and neutrons) is much, much smaller than the volume occupied by the electron cloud which is made up of the electrons of an atom and mostly empty space (since electrons are so tiny). This means that protons are neutrons are packed together into a small space and that electrons are very spread out.