When you increase the magnifying power of the microscope , you will see that the water molecule is made up of two tiny structures that are the same and a larger structure that is different from the two . These tiny structures are called " atoms . " The two tiny atoms which are the same are hydrogen atoms and the larger different one is an oxygen atom . When two atoms of hydrogen combine with one atom of oxygen , you have a molecule of water .
While water is made up of only two kinds of atoms - oxygen and hydrogen - the molecules of many materials are more complex in structure. Cellu- lose molecules, the basic molecules of which wood is made, consist of three different kinds of atoms - carbon, hydrogen and oxygen. All materials are made up of different combinations of atoms to form molecules of the materials. There are only about 100 different kinds of atoms and these are known as elements: oxygen, carbon, hydrogen, iron, gold, nitrogen are all elements. The human body with all its complex tissues, bones, teeth, etc. is made up of only 15 elements, and only six of these are found in reason-able quantities.
The Breakdown of the Atom Now that you know that all materials are made up of molecules which consist of various combinations of about only 100 different types of atoms, you will want to know what all this has to do with electricity. Increase the magnification of your imaginary super microscope still further and exam- ine one of the atoms you find in the water molecule.
Pick out the smallest atom you can see - the hydrogen atom - and examine it closely. HYDROGEN ATOM You see that the hydrogen atom is like a sun with one planet spinning around it. The planet is known as an " electron " and the sun is known as the " nucleus . " The electron has a negative charge of electricity and the nucleus has a positive charge of electricity . In an atom, the total number of negatively-charged electrons circulating. around the nucleus exactly equals the number of extra positive charges in the nucleus.
The positive charges are called "protons." Besides the pro-tons, the nucleus also contains electrically neutral particles called "neu-trons," which are made up of a proton and an electron bonded together. Atoms of different elements contain different numbers of neutrons within the nucleus, but the number of electrons spinning about the nucleus always equals the number of free protons within the nucleus. NEUTRONS 888 88800 ELECTRONS PROTONS The CARBON ATOM Electrons in the outer orbits of an atom are attracted to the nucleus by less force than electrons whose orbits are near the nucleus.
These outer electrons are called "free" electrons and may be easily forced from their orbits, while electrons in the inner orbits are called "bound" electrons since they cannot be forced out of their orbits easily. It is the motion of the free electrons that makes up an electric current.
What It In Now let's stop and review what you have found out about electricity and the electron theory . Then you will be ready to study where elec- tricity comes from .
1. MOLECULE - The combination of two or more atoms .
2. ATOM - The smallest physical particle into which an element can be divided .
3. NUCLEUS - The heavy positively - charged part of the atom which does not move .
4. NEUTRON - The heavy neutral particle in the nucleus consisting of a proton and an electron .
5. PROTON - The heavy positively - charged particle in the nucleus .
6. ELECTRON - The very small negatively- charged particle which is practically weightless and circles the nucleus .
7. BOUND ELECTRONS - Electrons in the inner orbits of an atom , which cannot easily be forced out of their orbits .
8. FREE ELECTRONS - Electrons in the outer orbits of an atom , which can easily be forced out of their orbits .
9. ELECTRICITY - The effect of electrons in moving from point to point , or the effect of too many ( excess ) or too few ( lack of ) electrons in a material .
10 The Six Sources of Electricity To produce electricity, some form of energy must be used to bring about " the action of electrons.
The six basic sources of energy which can be used are FRICTION, PRESSURE, HEAT, LIGHT, MAGNETISM and CHEM- ICAL ACTION. Before getting into the study of these sources, you will first find out about electric charges.
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