Historically the dining room is furnished with a rather large dining table and a number of dining chairs; the most common shape is generally rectangular with two armed end chairs and an even number of un-armed side chairs along the long sides.
Protons and neutrons do not have the same mass. Their masses are quite close, but they are noticeably different. For some purposes it is okay to equate the neutron and proton mass, but it's just an approximation.Also, neutrons decay into a proton, an electron and an antineutrino.rotons and neutrons do not have the same mass. Their masses are quite close, but they are noticeably different. For some purposes it is okay to equate the neutron and proton mass, but it's just an approximation.
Both protons and neutrons contain quarks. A proton comprises two up quarks and one down quark. A neutron contains two down quarks and one up quark. Quarks are pronounced 'corks' and are held together by gluons. Surrounding the nucleus, there are energy levels in which electrons orbit. Electrons have a negative charge. Of all the particles in an atom, only quarks and electrons are truly fundamental particles.