Editing 1939 in science (section)

==Chemistry==
* January 7 – French physicist [[Marguerite Perey]] identifies [[francium]], the [[Timeline of chemical element discoveries|last]] [[chemical element]] first discovered in nature, as a decay product of <sup>227</sup>Ac.<ref>{{cite web|url=http://elements.vanderkrogt.net/element.php?sym=fr|title=87 Francium|work=Elementymology & Elements Multidict|first=Peter|last=van der Krogt|accessdate=2019-01-07}}</ref>
* April 30 – [[Nylon]] fabric is first introduced to the general public at the [[1939 New York World's Fair|New York World's Fair]].
* July – [[Edward Adelbert Doisy]] of [[Saint Louis University]] publishes the chemical structure of [[vitamin K]].<ref>{{cite journal|last=MacCorquodale|first=D. W.|author2=Binkley, S. B.|author3=Thayer, S. A.|author4=Doisy, E. A.|year=1939|title=On the Constitution of Vitamin K<sub>1</sub>|journal=Journal of the American Chemical Society|volume=61|issue=7|pages=1928–1929|doi=10.1021/ja01876a510}}
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* [[Linus Pauling]] publishes ''The Nature of the Chemical Bond'', a compilation of a decade's work on [[chemical bonding]], explaining [[orbital hybridization|hybridization theory]], [[covalent bonding]] and [[ionic bonding]] as explained through electronegativity, and [[resonance (chemistry)|resonance]] as a means to explain, among other things, the structure of [[benzene]].<ref>{{cite web|title=Linus Pauling: The Nobel Prize in Chemistry 1954|work=Nobel Lectures, Chemistry 1942–1962|publisher=Elsevier|year=1964|url=http://nobelprize.org/nobel_prizes/chemistry/laureates/1954/pauling-bio.html|accessdate=2007-02-28}}</ref>