Sub-Atomic Particles: Protons, Neutrons, and Electrons

If Mrs. Frizzle planned to take her class on a Magic School Bus trip to explore the inside of an atom, students might ask if it was possible. Isn't an Aluminum atom just the smallest particle of solid aluminum metal possible? The simple answer is, "No" - and that's why a trip into an atom would not only be possible but a great learning experience.

All atoms are made up the same three types of much, much smaller sub-atomic particles:

protons, neutrons, and electrons. As indicated on the Periodic Table, the 92 different natural atoms just have different numbers of these super small particles of matter.

A Magic School Bus trip entitled, "A Journey to the Center of an Atom" would reveal three regions: 1) an outer 'cloud' of rapidly moving electrons, 2) mostly empty space, and 3) a tiny, super dense central core containing a specific number of mass particles (protons and neutrons) that determine the identity of each atom.

At this point you are hopefully wondering how scientists discovered the sub-atomic particles if they are way too small to be seen. Proving the existence of electrons(-) and protons(+) was made possible thanks to their "negative (-)" and "positive (+)" electrical charges. Neutrons having no electric charge, were much more difficult (but not impossible) to find.

And so, electrons and protons were discovered based on their behaviors in the presence of known electric charges. Electrons were repelled by a negative electric field and protons were discovered when the nuclei of atoms repelled small positively charged particles.