You may have built a scale model of a car, or a scale model of a town using Legos®.  If you tried to create a scale model of an atom, however, you would have a very difficult time!  Why?  The sizes of the particles in an atom are very different!  An electron is at least 10,000 times smaller than a proton.  Also, the entire atom is 10,000 times larger than the nucleus (remember that the atom is mostly empty space).

Imagine that you are creating a model of a hydrogen atom.  If you represent the proton with a basketball, the electron would be 10 miles away and about the size of the period at the end of a sentence!  If you created this model, you could fly a large jet through the atom and never hit the electron or the proton!

The red arrow is pointing to the period.

Think about this:

Electrons do not circle the nucleus in regular orbits like planets circle the sun. Electrons are randomly located around the nucleus, traveling in different directions, and impossible to locate at any definite time.