Positive Ions Whose Charges Do Not Vary
103
electrically neutral; they are positively charged ions. At all times, the solutions
or crystals that contain ions are electrically neutral, because the total number of
negative charges gained by one group of atoms always exactly equals the total
number of positive charges created in the groups from which the electrons
came. Ions tend to stay in the vicinity of each other because of the attraction of
opposite electrical charges. Ions that contain more than one atom in stable
combinations often are called radicals. In addition to explaining the electrical
conductivity of water solutions, ions are important because a tremendous number of chemical reactions take place between them.
Inorganic compounds also may be classified as acids, bases, and salts. This
classification is particularly useful as a basis for naming the chemicals with
which we shall deal.
The names of the elements (and many of the symbols used to represent them)
are traditional, rather than part of a logical system. The electrical charges that
the ions usually carry can be reasoned out, but chemists do not work through
such reasoning every time they want to use the charges or talk about them; they
simply know them as characteristic properties.
Once you have learned the symbols for the elements, you will easily recognize and understand formulas. A formula is the shorthand notation used to
identify the composition of a molecule. It includes the symbol of each element
in the molecule, with numerical subscripts to show how many atoms of each
element are present if there are more than one. For example, the formula for
sulfuric acid, H 2 SO 4 , shows that this molecule has 2 hydrogen atoms, 1 sulfur
atom, and 4 oxygen atoms. Note that a molecular formula does not tell how the
atoms are bound together, only the kinds and numbers of atoms.
Listed in the paragraphs that follow are the names, symbols, and usual electrical charges for 30 common positive ions, and the names and formulas for 37
common acids that are frequently mentioned in this text. You should memorize
these so as to have them at instant recall; the use of flash cards or other
foreign-language learning aids is recommended (computer-generated drill programs also are helpful). Aside from the direct intrinsic value of these names and
formulas, you can reason out from them the names and formulas of almost 50
bases and over 1600 different salts, none of which should be memorized.
POSITIVE IONS WHOSE CHARGES DO NOT VARY
The ions listed in Table 8-1 carry exactly the same names as the elements from
which they are derived. For example, Na and Mg are sodium and magnesium
atoms, whereas Na
+ and Mg+ are sodium and magnesium ions. These elements
do not normally form ions that have charges other than those shown.*
* Some of the elements listed here do exhibit other charges under very unusual conditions, but
this occurs so infrequently that we need not worry about it here. The principal exception, H~, is
discussed on page 109.
103
electrically neutral; they are positively charged ions. At all times, the solutions
or crystals that contain ions are electrically neutral, because the total number of
negative charges gained by one group of atoms always exactly equals the total
number of positive charges created in the groups from which the electrons
came. Ions tend to stay in the vicinity of each other because of the attraction of
opposite electrical charges. Ions that contain more than one atom in stable
combinations often are called radicals. In addition to explaining the electrical
conductivity of water solutions, ions are important because a tremendous number of chemical reactions take place between them.
Inorganic compounds also may be classified as acids, bases, and salts. This
classification is particularly useful as a basis for naming the chemicals with
which we shall deal.
The names of the elements (and many of the symbols used to represent them)
are traditional, rather than part of a logical system. The electrical charges that
the ions usually carry can be reasoned out, but chemists do not work through
such reasoning every time they want to use the charges or talk about them; they
simply know them as characteristic properties.
Once you have learned the symbols for the elements, you will easily recognize and understand formulas. A formula is the shorthand notation used to
identify the composition of a molecule. It includes the symbol of each element
in the molecule, with numerical subscripts to show how many atoms of each
element are present if there are more than one. For example, the formula for
sulfuric acid, H 2 SO 4 , shows that this molecule has 2 hydrogen atoms, 1 sulfur
atom, and 4 oxygen atoms. Note that a molecular formula does not tell how the
atoms are bound together, only the kinds and numbers of atoms.
Listed in the paragraphs that follow are the names, symbols, and usual electrical charges for 30 common positive ions, and the names and formulas for 37
common acids that are frequently mentioned in this text. You should memorize
these so as to have them at instant recall; the use of flash cards or other
foreign-language learning aids is recommended (computer-generated drill programs also are helpful). Aside from the direct intrinsic value of these names and
formulas, you can reason out from them the names and formulas of almost 50
bases and over 1600 different salts, none of which should be memorized.
POSITIVE IONS WHOSE CHARGES DO NOT VARY
The ions listed in Table 8-1 carry exactly the same names as the elements from
which they are derived. For example, Na and Mg are sodium and magnesium
atoms, whereas Na
+ and Mg+ are sodium and magnesium ions. These elements
do not normally form ions that have charges other than those shown.*
* Some of the elements listed here do exhibit other charges under very unusual conditions, but
this occurs so infrequently that we need not worry about it here. The principal exception, H~, is
discussed on page 109.