Albert Louis Allred (born September 19, 1931) is an American chemist accomplished in the fields of inorganic chemistry and

electronegativity Electronegativity, symbolized as , is the tendency for an atom of a given chemical element to attract shared electrons (or electron density) when forming a chemical bond. An atom's electronegativity is affected by both its atomic number and the ...

. He was born in Mount Airy,

North Carolina North Carolina () is a state in the Southeastern region of the United States. The state is the 28th largest and 9th-most populous of the United States. It is bordered by Virginia to the north, the Atlantic Ocean to the east, Georgia and ...

, United States.

Education and career

Allred studied chemistry at the

University of North Carolina The University of North Carolina is the multi-campus public university system for the state of North Carolina. Overseeing the state's 16 public universities and the NC School of Science and Mathematics, it is commonly referred to as the UNC Sy ...

and earned a bachelor's degree in 1953. He studied at

Harvard University Harvard University is a private Ivy League research university in Cambridge, Massachusetts. Founded in 1636 as Harvard College and named for its first benefactor, the Puritan clergyman John Harvard, it is the oldest institution of high ...

and earned a master's degree in 1955, followed by a doctorate in 1957. In 1956 he was an instructor, 1958 assistant professor, and 1969 professor at the College of Arts and Sciences of

Northwestern University Northwestern University is a private research university in Evanston, Illinois. Founded in 1851, Northwestern is the oldest chartered university in Illinois and is ranked among the most prestigious academic institutions in the world. Charte ...

. From 1980 to 1986, he was chairman of the chemistry department. In 1992, he became acting vice president for research as well as dean of the graduate school. In 1987, he was a visiting scholar at

Cambridge University The University of Cambridge is a Public university, public collegiate university, collegiate research university in Cambridge, England. Founded in 1209 and granted a royal charter by Henry III of England, Henry III in 1231, Cambridge is the world' ...

, in 1965 Honorary Research Associate at University College London and in 1967 at the University of Rome. From 1963 to 1965, he was a Sloan Research Fellow. He has been a Fellow of the American Association for the Advancement of Science since 1981. Allred introduced the Allred-Rochow scale of electronegativity with

Eugene G. Rochow Eugene George Rochow (October 4, 1909 – March 21, 2002) was an American inorganic chemist. Rochow worked on organosilicon chemistry; in the 1940s, he described the direct process, also known as the Rochow process or Müller-Rochow process. Bo ...

in 1958. They predicted that electronegativity, should be related to the charge experienced by an electron on the "surface" of an atom. They calculated this formula for the electronegativity, '' χ'', where "

Z_

" is equal to the

effective nuclear charge In atomic physics, the effective nuclear charge is the actual amount of positive (nuclear) charge experienced by an electron in a multi-electron atom. The term "effective" is used because the shielding effect of negatively charged electrons prevent ...

and "

r_

" is the

covalent radius The covalent radius, ''r''cov, is a measure of the size of an atom that forms part of one covalent bond. It is usually measured either in picometres (pm) or angstroms (Å), with 1 Å = 100 pm. In principle, the sum of the two coval ...

. When the covalent radius is expressed in

picometers The picometre (international spelling as used by the International Bureau of Weights and Measures; SI symbol: pm) or picometer (American spelling) is a unit of length in the International System of Units (SI), equal to , or one trillionth of ...

: ::

\chi = 3590 + 0.744

. When expressed in

Angstroms The angstromEntry "angstrom" in the Oxford online dictionary. Retrieved on 2019-03-02 from https://en.oxforddictionaries.com/definition/angstrom.Entry "angstrom" in the Merriam-Webster online dictionary. Retrieved on 2019-03-02 from https://www.m ...

however, the value 3590, becomes .359. ::

\chi = .359 + 0.744

He also since has dealt with synthetic inorganic, organometallic chemistry, and electrochemistry.

References

{{DEFAULTSORT:Allred, Albert American chemists Scientists from North Carolina University of North Carolina alumni Harvard Graduate School of Arts and Sciences alumni Northwestern University faculty Living people 1931 births