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All matter is made of small particles called
atoms. Atoms are far too small
to be seen with the naked eye or even with a microscope. In fact,
more than a trillion atoms could fit over the period at the end of a
sentence. There are
about 90 different kinds of atoms found in nature.
Matter made up of all one kind of atom is called an
element.
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Some Familiar
Elements and Their Symbols |
|
Element |
Symbol |
Element |
Symbol |
Element |
Symbol |
|
Hydrogen |
H |
Phosphorous |
P |
Chlorine |
Cl |
|
Oxygen |
O |
Sulfur |
S |
Sodium |
Na |
|
Carbon |
C
|
Magnesium |
Mg |
Gold |
Au |
|
Nitrogen |
N |
Silicon |
Si |
Tin |
Sn |
Clearly, however, there are more than 90 different kinds of matter in our
world. This is because atoms can combine
in
chemical reactions to
produce a myriad of new substances. For example, when one atom of sodium
(which by itself is a soft metal) and one atom of chlorine (which by
itself is a poison green gas) combine, the result is a compound called sodium chloride, more
commonly known as table salt.
A
compound is made up of
two or more elements that are chemically bonded.
|
 |
 |
 |
 |
 |
|
Na
sodium |
|
Cl
chlorine |
|
NaCl
table salt |
A
molecule is the
smallest particle of a compound that has all the properties of that
compound. We write the
molecular formula
of salt as NaCl
to indicate it has one atom of sodium and one atom of chlorine.
(Click here for more about writing molecular formulae.)
Since you may not wish to explore the complexities of chemical
bonding as part of your genealogical research, you might find it useful to
compare atoms to a variety of differently sized and shaped lego building
blocks which can be fitted together in a variety of ways to form a
multitude of different creations. Similarly, the
atoms of each element are distinguished by their
mass and by the number of connections they can make with other atoms.
There is virtually an infinite variety of compounds possible.
Some molecules are small, such as water, H2O,
which has only three atoms and table salt NaCl which has two. Others are
larger such as a molecule of table sugar, C12H22O11
(sucrose) which has 45 atoms. Still other molecules, such as proteins,
are gigantic, sometimes containing tens of thousands of atoms.
These
gigantic molecules are called macromolecules.
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