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ALKALINE EARTHS

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Originally appearing in Volume V01, Page 685 of the 1911 Encyclopedia Britannica.
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ALKALINE EARTHS . The so-called alkaline See also:

earth-metals are the elements See also:beryllium, See also:magnesium, See also:calcium, See also:strontium and See also:barium. By the See also:early chemists, the See also:term earth was used to denote those non-metallic substances which were insoluble in See also:water and were unaffected by strong See also:heating; and as some of these substances (e.g. See also:lime) were found to be very similar in properties to those of the alkalis, they were called alkaline earths. The alkaline earths were assumed to be elements until 1807, when See also:Sir H. See also:Davy showed that they were oxides of various metals. The metals comprising this See also:group are never found in the uncombined See also:condition, but occur most often in the See also:form of See also:carbonates and sulphates; they form oxides of the type RO, and in the See also:case of calcium, strontium and barium, of the type R02. The oxides of type RO are soluble in water, the See also:solution possessing a strongly alkaline reaction and rapidly absorbing See also:carbon dioxide on exposure; they are basic in See also:character and dissolve readily in acids with the formation of the corresponding salts. As the atomic See also:weight of the See also:element increases, it is found that the solubility of the sulphates in water decreases. Beryllium to a certain extent stands alone in many of its chemical properties, resembling to some extent the See also:metal See also:aluminium. Beryllium and magnesium are permanent in dry See also:air; calcium, strontium and barium, however, oxidize rapidly on exposure. The salts of all the metals of this group usually crystallize well, the chlorides and nitrates dissolve readily in water, whilst the carbonates, See also:phosphates and sulphates a're either very sparingly soluble or are insoluble in water.

End of Article: ALKALINE EARTHS

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