Page 30 - Bebop to The Boolean Boogie An Unconventional Guide to Electronics Fundamentals, Components, and Processes

Atoms, Molecules, and Crystals rn I1

When the two borrowed electrons are added to the original six in the oxygen
atom’s second shell, this shell appears to contain the eight electrons necessary to
fill it. Thus, all the atoms in the water molecule are satisfied with their lot and
the molecule is stable.
Structures other than molecules may be formed when atoms bond; for
example, crystals. Carbon, silicon, and germanium all belong to the same family
of elements; each has only four electrons in its outermost electron shell. Silicon
has 14 protons and 14 electrons; two electrons are required to fill the first
electron shell and eight to fill the second shell; thus, only four remain for the
third shell, which would ideally prefer eight. Under the appropriate conditions,
each silicon atom will form bonds with four other silicon atoms, resulting in a
three-dimensional silicon crystal6 (Figure 2-5).
The electrons used to form the bonds in crystalline structures such as silicon
are tightly bound to their respective atoms. Yet another structure is presented
by metals such as copper, silver, and gold. Metals have an amorphous crystalline
structure in which their shared electrons have relatively weak bonds and may
easily migrate from one atom to another.
Apart from the fact that atoms
are the basis of life, the universe,
and everything as we know it,
they are also fundamental to the
operation of the components used
in electronic designs. Electricity
may be considered to be vast herds
of electrons migrating from one I1
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place to another, while electronics I1
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II
is the science of controlling these
- - - - - - - - - - - - -
herds: starting them, stopping them, - - - - - - - - - - - - -
deciding where they can roam, and I1
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determining what they are going to I1
Figure 2-5. Simplified (two-dimensional)
do when they get there.
representation of the three-dimensional
structure of crystalline silicon

6 An equivalent structure formed from carbon atoms is known as diamond.