Page 29 - Teach Yourself Electricity and Electronics

Compounds 9

1-2 Electrons move around the nucleus of an atom at defined levels corresponding
to different energy states. This is a simplified drawing, depicting an electron
gaining energy.

A good example of an ionized substance is the atmosphere of the earth at high
altitudes. The ultraviolet radiation from the sun, as well as high-speed subatomic par-
ticles from space, result in the gases’ atoms being stripped of electrons. The ionized
gases tend to be found in layers at certain altitudes. These layers are responsible for
long-distance radio communications at some frequencies.
Ionized materials generally conduct electricity quite well, even if the substance is
normally not a good conductor. Ionized air makes it possible for a lightning stroke to
take place, for example. The ionization, caused by a powerful electric field, occurs along
a jagged, narrow channel, as you have surely seen. After the lightning flash, the nuclei
of the atoms quickly attract stray electrons back, and the air becomes electrically neu-
tral again.
An element might be both an ion and an isotope different from the usual isotope.
For example, an atom of carbon might have eight neutrons rather than the usual six,
thus being the isotope C14, and it might have been stripped of an electron, giving it a
positive unit electric charge and making it an ion.

Compounds

Different elements can join together to share electrons. When this happens, the result
is a chemical compound. One of the most common compounds is water, the result of
two hydrogen atoms joining with an atom of oxygen. There are literally thousands of dif-
ferent chemical compounds that occur in nature.