Editing Robert S. Mulliken (section)

==Later years==
In 1934, he derived a new scale for measuring the [[electronegativity]] of elements. This does not entirely correlate with the scale of [[Linus Pauling]], but is generally in close correspondence.

In [[World War II]], from 1942 to 1945, Mulliken directed the Information Office for the University of Chicago's [[Plutonium]] project. Afterward, he developed mathematical formulas to enable the progress of the molecular-orbital theory.

In 1952 he began to apply [[quantum mechanics]] to the analysis of the reaction between [[Lewis acids and bases|Lewis acid]] and [[Base (chemistry)|base]] [[molecule]]s. (See [[Acid-base reaction theories]].) In 1961, he became Distinguished Professor of Physics and Chemistry at [[Florida State University]], and continued in his studies of [[molecular structure]] and [[spectroscopy|spectra]], ranging from diatomic molecules to large complex aggregates. In 1981, Mulliken became a founding member of the [[World Cultural Council]].<ref>{{cite web | title = About Us | publisher = [[World Cultural Council]] | url = http://www.consejoculturalmundial.org/members/ | access-date = November 12, 2022}}</ref> In 1983, Mulliken received the Golden Plate Award of the [[Academy of Achievement|American Academy of Achievement]].<ref>{{cite web|title= Golden Plate Awardees of the American Academy of Achievement |website=www.achievement.org|publisher=[[American Academy of Achievement]]|url=https://achievement.org/our-history/golden-plate-awards/#science-exploration}}</ref> He retired in 1985. His wife died in 1975.

At the age of 90, Mulliken died of congestive heart failure at his daughter's home in [[Arlington County, Virginia]] on October 31, 1986. His body was returned to [[Chicago]] for burial.