The element of symbols: symbols to know

Chemical symbols are shorten abbreviations of the names of the 109 known elements. The use of symbols for the chemical elements existed long before a systematic method was developed. the alchemist associated the symbols of the planets not only with the days of the week, but also with the seven metals known at the time: gold, silver, iron, mercury, tin, copper , and lead. By the beginning of the nineteenth century, there were about  26 known elements, but by the beginning of the twentieth century, therer were more than 81.

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