Natural Radioactivity -Definition and Discovery

NATURAL RADIOACTIVITY

·       Radioactivity is a spontaneous and self disintegrating activity exhibited by several elements having mass number greater than 206.

·       During the process, a complex type of radiation is emitted.

·       It is an irreversible process and is unaffected by physical or chemical conditions of the element. 

Discovery

·       Radioactivity was discovered accidentally by Henry Becquerel in 1896 during the study of fluorescence exhibited by double sulphate of uranium, activated by sunlight.

·       It was found that some sort of powerful radiations coming from the uranium salt affected the photographic plate wrapped in black paper.

·       Even when the photographic plate was kept in light tight box, it was affected.

·       Hence it followed that uranium salt gave out certain powerful radiations.

·       These radiations were first called Becquerel rays.

·       Later the name radioactivity was given to the phenomenon.

·       Further investigations were conducted by Pierre Curie and Madam Curie.

·       They have shown that radioactivity is a property of the atom of the element in the compound since the radiations are unaffected by the physical and chemical changes of the compound.

·       The most important discovery made by them is that of the new radioactive elements, radium and polonium.

NExT: Self Assessment MCQ

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