BASIC FACTS OF NUCLEAR PHYSICS

In recent years tremendous advances have been made in the development of various, branches of physics.

The most remarkable researchers of the twentieth century have substantiated two ideas about the nature of the matter which the Greek philosophers formulated twenty centuries ago. One is the theory that the many thousands of substances which exist in the world are formed out of a small number of simpler substances or elements (molecules). The other theory is that matter is constructed out of tiny particles or units, the so-called atoms of matter.

The modern scientist is convinced of the existence of molecules and atoms. Everything in and on the earth, the moon, the sun, and all other stars, is made of atoms. Billions of atoms together make everything that exists. Take a handful of air, and you will hold billions of atoms.

Look at your handful of atoms. You can't see a single one, no matter how hard you look, for every atom is too small to be seen even with a powerful microscope.

The atoms which form the molecules are, of course, smaller than the molecules, while the electrons of which the atoms are composed are yet smaller. From various experiments scientists concluded that the diameter of the average molecule is about one 125,000,000 of an inch. Since atoms compose molecules, they must be still smaller. If each atom in an orange measured one inch in diameter, the orange would be as large as the earth.

1. What are the advances of physics in our days?

2. What latest achievements in the field of physics have you heard about?

3. What ideas about the nature of the matter have the researchers of the 20^th century substantiated?

4. What do you know about the atomic theory of matter?

5. What do you know about the structure of the molecule?

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