Ratty Grierson, age 12 of Montgomery, Ala., for his question:

How close are the particles in an atom?

Maybe someday, someone will invent a microscope powerful enough to reveal the inside workings of an atom. Until then, we must rely on the detective work done by the scientists to explain these minute particles of matter to us. Every tiny atom, they tell us, is composed of even smaller particles. Some of these particles have charges of positive electricity, some of negative electricity and others are electrically neutral.

The positive protons and the negative neutrons are bundled fairly close together in the center of the atom. They farm the bulk of the atom in a core or nucleus, Around this nucleus whirl the negative electrons    rather like planets of a solar system. They are far, far smaller than either protons or neutrons.

In a real monster solar system there is plenty of room for every¬thing. There is plenty of space between the sun and its planets and none of the planets crowd each other. The same holds true of the atom and the minute particles of which it is made. Most of an atom is dust empty space. As far as we can discover, the central nucleus inside an atom has about as much room as a fly has in a movie house.