File:Periodic table discovery periods.png

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Summary

DescriptionPeriodic table discovery periods.png	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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File history

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	Date/Time	Dimensions	User	Comment
current	05:47, 4 November 2012	687 × 502 (111 KB)	Double sharp	fix positioning of group 3 label
	03:01, 4 November 2012	687 × 502 (111 KB)	Double sharp	added 113–118
	08:13, 3 November 2012	687 × 502 (110 KB)	Double sharp	insert Cn. I'll add the others based on FAC comments
	23:50, 2 April 2010	687 × 502 (98 KB)	Krauss	cut the legend (that goes by text): see http://en.wikipedia.org/wiki/History_of_the_periodic_table
	23:15, 2 April 2010	687 × 554 (105 KB)	Krauss	{{Information \|Description={{en\|1=Periodic Table, main "discovery periods"}} \|Source=http://old.iupac.org/reports/periodic_table/index.html \|Author=IUPAC \|Date=2004 \|Permission= \|other_versions= }} it is for free usage! (and periodic table fig is public d