CHAPTER VALKALI AND ALKALINE EARTH METALSThese metals constitute the left-hand or A families in Groups I
and II of the periodic classification of the elements, as shown in
the table inside the back cover of the book.
The metals of these two families are studied together because
they are extremely active base-forming elements. On account
of their great activity they are never found uncombined in nature,
and it is only by the aid of the most powerful reducing agencies
(for example, by electrolysis of their molten salts) that the metals
themselves are extracted from their compounds.
The alkali metals are monovalent. Their hydroxides, MOH,
are extremely soluble and are highly ionized as bases; on account
of the corrosive properties of the latter they are known as the
caustic alkalies — hence the designation, alkali metals. The
compounds of the alkali metals are, with a very few exceptions,
soluble in water, and they are all strong electrolytes.
The radical ammonium, NH 4 , is classed with the alkali metals
on account of its ability to form the same kinds of compounds.
The alkaline earth metals are divalent; their hydroxides,
M(OH) 2 , are less soluble than those of the alkali metals, but are
nevertheless very strongly basic. The compounds of these metals
are not so generally soluble as those of the alkali metals, and in
particular the carbonates, sulphates, and phosphates are mostly
insoluble.
PREPARATION 15
SODIUM CARBONATE BY THE AMMONIA (SOLVAY) PROCESS, Na 8 CO 3
The raw materials from which the sodium carbonate of com-
merce is manufactured are common salt, NaCl, and limestone,
CaCO 3 , but these substances do not spontaneously react with
each other, rather a reaction would take place in the opposite
direction, as indicated by the arrow.
2NaCl + CaCO 3 *- CaCl 2 + Na 2 CO 3
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