radium

Definition

The chemical element (symbol Ra) with an atomic number of 88. It is a soft, shiny and silvery radioactive alkaline earth metal.

Etymology

Borrowed from French radium, from rad(ioactif) (“radioactive”) + -ium (suffix used to form the names of metallic elements).

Example Sentences

• "Madame [Marie] Curie, working with her distinguished husband, isolated and first traced to its true origin the source of the marvellous power which has thus commenced to revolutionise our philosophy of physics. This new element has appropriately been named "Radium;" but it has also been shown that there are many other, though less powerful, radio-active elements, details of which are recorded in the sequel. To be precise, radium, per se, has not yet been isolated as a metal, but only in the form of salts,—chlorides and bromides. [...] It is supposed that the molecules of radium (composed of similar atoms) during their decomposition into those of the gas helium, are also frittered down into heat and, in part, are liberated as radio-activity."
• "The persistence of radio-activity on glass vessels which have contained radium is remarkable. Filters, beakers, and dishes used in the laboratory for operations with radium, after having been washed in the usual way, remain radio-active: a piece of blende screen held inside the beaker or other vessel immediately glowing with the presence of radium."
• "The object of this work is to determine how the radiums D, E, and F are separated from the substance known as radio-lead by certain chemical reactions. Recrystallisation of the nitrate from a neutral solution gradually removes the radium-F (polonium), which remains in the mother liquor, but does not appreciably influence the amounts of radiums D and E in the crystals."

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