Electrons, protons, and neutrons are the three fundamental particles in an atom. Electron is a negatively charged particle, and according to Dalton's Atomic Theory, electrons are found outside the nucleus, and they orbit the nucleus. Protons, on the other hand, are positively charged particles found inside the nucleus of an atom together with neutrons. Protons consist of other simpler particles, while electrons do not consist of other simpler particles. Since both protons and neutrons have opposite charges, electrons will always revolve around the nucleus in a bid to get attracted to a proton.
And since the number of electrons in an atom is equal to the number of protons, therefore, we have a neutral atom. Electron is usually represented with the symbol e-, while a proton is represented with the symbol p+. The relative mass of an electron is 0.00055, whereas the relative mass of a proton is 1. The atomic number of an atom can be calculated by knowing the number of particles or protons in a molecule.