General Remarks on the Chemistry of the Metals

Although the number of the metallic elements is much greater than that of the non-metals, the chemistry of them is much simpler and comparatively less diverse. This is due to the fact that by far the largest number and the most important of the compounds of the metals are of a saline character. Now, we have seen generally that the properties of the salts in aqueous solution are conditioned essentially by the properties of their ions. If, therefore, a metal, e.g. silver, forms only one kind of cation, the behaviour of all its salts in aqueous solution is known, if that of this particular cation is known; a knowledge of the anions, which have mostly been treated in the chemistry of the non-metals, is hereby supposed given.

So far, then, as the behaviour in aqueous solution is concerned, the chemistry of the metals is essentially given with the knowledge of the metal ions. In analytical chemistry we are concerned almost entirely with aqueous solutions, and to what we there learn it is generally sufficient to add a statement of the solubility relations of certain difficultly soluble salts, in order to obtain the foundation of analytical chemistry. For general chemistry, however, it is necessary to add a knowledge of the compounds in the solid state as well as of the non-saline or indifferent compounds which also exist in the case of the metals, whereby greater diversity is produced.

Some variety is, however, found among the ions themselves. Many metals form not only elementary ions with different properties, the differences between which are connected with different valency, but they are also capable of forming with other elements complex ions with special properties. New groups of substances are thereby formed, and in this direction inorganic chemistry is developing a very great diversity, which at the present time is by no means exhausted - in many cases, indeed, its outlines are scarcely known.

In general, every anion will be able to form a salt with every cation. By virtue of a general rule, most of the salts in dilute aqueous solution are extensively dissociated into their ions, so that the properties of these solutions differ but little from the sum of the properties of the ions. Where, therefore, specific properties, which do not correspond to this rule, are met with in salt solutions, it can be concluded with certainty that the dissociation of the salt present is small. From the comparatively great rarity of such exceptions, there follows, conversely, the great generality of the rule just stated.

In the following descriptions of the different metals, therefore, stress will be laid on the statement of the ions which can be formed from them, and the properties essential for their characterisation will be mentioned. In general, the methods employed for the detection and determination of the metals will be thereby given. To this there is added the chemistry of those solid compounds of the metals which are in any way important enough to find mention in this elementary work.