File:Periodic table discovery periods.png

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Summary

Description	English: Periodic Table, main "discovery periods"
Date	2004
Source	http://old.iupac.org/reports/periodic_table/index.html
Author	IUPAC

Legend:

Before 1800 (38 elements): discoveries during and before the age of enlightenment.
1800-1849 (+22 elements): science and industrial revolutions.
1850-1899 (+23 elements): the age of classifying elements recived the impulse of the spectrum analysis. Boisbaudran, Bunsen, Crookes, Kirchhoff, and others "hunting wikipedia:emission line signatures".
1900-1949 (+13 elements): impulse with the wikipedia:old quantum theory and wikipedia:quantum mechanics.
1950-present (+22 elements): "post atomic bomb" issues for atomic numbers 97 and above (colliders, bombardment techniques).

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Horizontal resolution	37.8 dpc
Vertical resolution	37.8 dpc
File change date and time	23:48, 2 April 2010
PNG file comment	Created with GIMP

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