Atomic and Nuclear Physics
DOE-HDBK-1019/1-93
ATOMIC NATURE OF MATTER
Each type of atom that contains a unique combination of
Figure 2 Nomenclature for
Identifying Nuclides
protons and neutrons is called a nuclide.
Not all
combinations of numbers of protons and neutrons are
possible, but about 2500 specific nuclides with unique
combinations of neutrons and protons have been
identified. Each nuclide is denoted by the chemical
symbol of the element with the atomic number written as
a subscript and the mass number written as a superscript,
as shown in Figure 2. Because each element has a
unique name, chemical symbol, and atomic number, only
one of the three is necessary to identify the element. For
this reason nuclides can also be identified by either the
chemical name or the chemical symbol followed by the
mass number (for example, U-235 or uranium-235).
Another common format is to use the abbreviation of the
chemical element with the mass number superscripted (for example, 235U). In this handbook the
format used in the text will usually be the element's name followed by the mass number. In
equations and tables, the format in Figure 2 will usually be used.
Example:
State the name of the element and the number of protons, electrons, and neutrons in the
nuclides listed below.
1
1
H
10
5
B
14
7
N
11
4
4
8
Cd
23
9
9
4
Pu
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