Chemistry Reference
In-Depth Information
Chemical Notation and Nomenclature
An internationally accepted
chemical notation
makes use of
symbols
to
represent elements and compounds, and advises on naming chemical
compounds. In this notation, the elements are represented by one or two
letters, many of which are drawn from the elements' Latin or Greek names.
The number of atoms of an element in a molecule is represented by a sub-
script written after the symbol; thus Au (the first two letters of
aurum
, the
Latin name for gold) represents an atom of gold; Cu (the first two letters
of
cuprum
, the Latin name for copper), an atom of copper; and C (the first
letter of carbon), an atom of carbon; O represents an atom of oxygen and
O
2
, a molecule of oxygen. The symbols listed below provide examples of
the presently accepted form of chemical notation:
Ag:
silver (
argentum
)
Au:
gold (
aurum
)
C:
carbon
Cu:
copper (
cuprum
)
Fe:
iron (
ferrum
)
Hg:
mercury (
hydrargyrium
)
K:
potassium (
kalium
)
N:
nitrogen
O:
oxygen
P:
phosphorus
Pb:
lead (
plumbum
)
S:
sulfur
Sb:
antimony (
stibium
)
Sn:
tin (
stannum
)
Zn:
zinc
The internationally accepted notation also establishes the method of
expressing, with symbols, the composition of chemical compounds. These
are expressed by chemical formulas consisting of the symbols of the com-
ponent elements and numbers representing the relative amount of each
elemental component in a molecule of a compound (Fox and Powell 2001).
For any particular compound, the number of atoms of each element in a
molecule of the compound is indicated by a subscript written after the
symbol of the element; no subscript appears when there is only one atom
of the element. Thus the formula of water, whose molecule consists of two
atoms of hydrogen and one of oxygen, is H
2
O, and that of carbon dioxide,
whose molecule includes one atom of carbon and two of oxygen, is CO
2
.
The formula of glucose, C
6
H
12
O
6
, means, therefore, that its molecule
is composed of 6 atoms of carbon, 12 of hydrogen, and 6 of oxygen
[since glucose belongs to the type of organic compounds known as the
