J. L. Wallace, age 11, of Pop, Ala., for his question:

What Exactly is an atom?     

The atom is an orderly bundle of electrically charged particles. It has been Compared to a miniature solar system. In our big solar System, the planets and Other lumps of matter occupy but a small fraction of the vast reaches of empty space.  The particles of matter occupy but a small fraction of the tiny atom, and most of  an atom is empty space.     WE live in a world where things are always changing. Iron rusts. Granite forms from molten lava. Burning wood turns into gases and ashes. We can explain these bewildering changes if we believe in the atom. Let’s assume that all liquids, gases and solids are made of miniature particles of various kinds  and let’s call these fragments of matter atoms. A growing tree assembles assorted atoms to form wood. When wood burns, these atoms separate and go their separate ways.     It took Scientists a long time to track down the atom  but now we know. All the solid, liquid and gaseous forms of matter in the universe are made from atoms.  It takes 100 million atoms of iron to measure an inch  and all of them are atoms of the element iron. In our world, there are only 92 different atoms. WE call them the natural Elements. Physicists have created other elements, and the number now stands at 103.     Each atom is a unit of particles. It has a central nucleus charged with Positive Electricity. In some hydrogen atoms, the nucleus is a single protonparticle charged with positive Electricity. The nuclei of all other atoms have more than one proton plus a number of neutrons with neutral Electrical charges.  The nucleus of an atom is orbited with electron particles, which are charged with negative electricity. The hydrogen atom has one Electron, and all other atoms have more than one electron. The positive charge of a proton Exactly offsets the negative charge of an electron. The carbon atom, which has six protons, is orbited by six electrons. The copper atom, with 29 protons, has 29 electrons.     The known elements are arranged on a chart called the Periodic Table. Each element has an atomic number which te1ls the member of its protons. Carbon is Atomic number 6, copper is atomic number 29. The atomic weight of an element is the sum of all its particles. The atomic weight of carbon is 12.011, the atomic weight of copper is 63.51+.     Scientists figured out the structure of the atom from countless experiments Because atoms were too small for the most powerful microscopes. We can now magnify two million times  and even this does not give a clear picture of the tiny atom. But at least we can get shadow pictures which show how atoms are arranged in solid substances.