Robert S. Mulliken
Encyclopedia
Robert Sanderson Mulliken (June 7, 1896 – October 31, 1986) was an American
physicist
and chemist
, primarily responsible for the early development of molecular orbital theory
, i.e. the elaboration of the molecular orbital
method of computing the structure of molecule
s. Dr. Mulliken received the Nobel Prize
for chemistry in 1966. He received the Priestley Medal
in 1983.
. His father, Samuel Parsons Mulliken, was a professor of organic chemistry
at the Massachusetts Institute of Technology
. As a child, Robert Mulliken learned the name and botanical
classification of plant
s and, in general, had an excellent, but selective, memory. For example, he learned German
well enough to skip the course in scientific German in college, but could not remember the name of his high school German teacher. He also made the acquaintance, while still a child, of the physical chemist Arthur Amos Noyes
.
Mulliken helped with some of the editorial work when his father wrote his four-volume text on organic compound identification, and thus became an expert on organic chemical nomenclature.
. Already as an undergraduate, he did his first publishable research: on the synthesis of organic chlorides. Because he was unsure of his future direction, he included some chemical engineering
courses in his curriculum and spent a summer touring chemical plants in Massachusetts
and Maine
. He received his B. S.
degree
in chemistry from MIT in 1917.
had just entered World War I
, and Mulliken took a position at American University
in Washington, D.C.
, making poison gas under James B. Conant. After nine months, he was drafted into the Army's Chemical Warfare Service, but continued on the same task. His laboratory techniques left much to be desired, and he was out of service for months with burns. Later he got a bad case of influenza, and was still in the hospital at war's end.
After the war, he took a job investigating the effects of zinc oxide
and carbon black
on rubber
, but quickly decided that this was not the kind of chemistry he wanted to pursue. So in 1919 he entered the Ph.D.
program at the University of Chicago
.
s of mercury
by evaporation
, and continued in his isotope separation by this method. While at Chicago
, he took a course under the Nobel Prize-winning physicist
Robert A. Millikan, which exposed him to the old quantum theory
. He also became interested in strange molecules after exposure to work by Hermann I. Schlesinger on diborane
.
At Chicago, he had received a grant from the National Research Council
(NRC) which had paid for much of his work on isotope separation. The NRC grant was extended in 1923 for two years so he could study isotope effects on band spectra of such diatomic molecules as boron nitride (BN) (comparing molecules with B10 and B11). He went to Harvard University
to learn spectrographic technique from Frederick A. Saunders and quantum theory from E. C. Kemble. At the time, he was able to associate with many future luminaries, including J. Robert Oppenheimer, John H. Van Vleck, and Harold C. Urey. He also met John C. Slater
, who had worked with Niels Bohr
.
In 1925 and 1927, Mulliken traveled to Europe, working with outstanding spectroscopists and quantum theorists such as Erwin Schrödinger
, Paul A. M. Dirac
, Werner Heisenberg
, Louis de Broglie, Max Born
, and Walther Bothe
(all of whom eventually received Nobel Prizes) and Friedrich Hund
, who was at the time Born's assistant. They all, as well as Wolfgang Pauli
, were developing the new quantum mechanics
that would eventually supersede the old quantum theory. Mulliken was particularly influenced by Hund, who had been working on quantum interpretation of band spectra of diatomic molecules, the same spectra which Mulliken had investigated at Harvard. In 1927 Mulliken worked with Hund and as a result developed his molecular orbital
theory, in which electrons are assigned to states that extend over an entire molecule. In consequence, molecular orbital theory was also referred to as the Hund-Mulliken theory.
department at New York University
(NYU). This was his first recognition as a physicist; though his work had been considered important by chemists, it clearly was on the borderline between the two sciences and both would claim him from this point on. Then he returned to the University of Chicago as an associate professor of physics, being promoted to full professor in 1931. He would ultimately hold a position jointly in both the physics and chemistry departments. At both NYU and Chicago, he continued to refine his molecular-orbital theory.
Up to this point, the primary way to calculate the electronic structure of molecules was based on a calculation by Walter Heitler
and Fritz London
on the hydrogen
molecule (H2) in 1927. With the conception of hybridized atomic orbitals by John C. Slater
and Linus Pauling
, which rationalized observed molecular geometries, the method was based on the premise that the bonds
in any molecule could be described in a manner similar to the bond in H2, namely, as overlapping atomic orbitals centered on the atoms involved. Since it corresponded to chemists' ideas of localized bonds between pairs of atoms, this method (called the Valence-Bond (VB) or Heitler-London-Slater-Pauling (HLSP) method), was very popular. However, particularly in attempting to calculate the properties of excited states (molecules that have been excited by some source of energy), the VB method does not always work well. With its description of the electron wave functions in molecules as delocalized molecular orbitals that possess the same symmetry as the molecule, Hund and Mulliken's molecular-orbital method, including contributions by John Lennard-Jones
, proved to be more flexible and applicable to a vast variety of types of molecules and molecular fragments, and has totally eclipsed the valence-bond method. As a result of this development, he received the Nobel Prize in Chemistry in 1966.
Mulliken became a member of the National Academy of Sciences
in 1936, the youngest member in the organization's history, at that time.
Mulliken population analysis is named after him, a method of assigning charges to atoms in a molecule.
professor at the University of Chicago. They had two daughters.
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
acid
and base
molecule
s. (See Acid-base reaction theories
.) He became Distinguished Professor of Physics and Chemistry in 1961 and continued in his studies of molecular structure
and spectra
, ranging from diatomic molecules to large complex aggregates. He retired in 1985.
He died of congestive heart failure at his daughter's home in Arlington, Virginia (across the Potomac River
from Washington, D.C.
) on October 31, 1986. His body was returned to Chicago
for burial.
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
physicist
Physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...
and chemist
Chemistry
Chemistry is the science of matter, especially its chemical reactions, but also its composition, structure and properties. Chemistry is concerned with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds....
, primarily responsible for the early development of molecular orbital theory
Molecular orbital theory
In chemistry, molecular orbital theory is a method for determining molecular structure in which electrons are not assigned to individual bonds between atoms, but are treated as moving under the influence of the nuclei in the whole molecule...
, i.e. the elaboration of the molecular orbital
Molecular orbital
In chemistry, a molecular orbital is a mathematical function describing the wave-like behavior of an electron in a molecule. This function can be used to calculate chemical and physical properties such as the probability of finding an electron in any specific region. The term "orbital" was first...
method of computing the structure of molecule
Molecule
A molecule is an electrically neutral group of at least two atoms held together by covalent chemical bonds. Molecules are distinguished from ions by their electrical charge...
s. Dr. Mulliken received the Nobel Prize
Nobel Prize
The Nobel Prizes are annual international awards bestowed by Scandinavian committees in recognition of cultural and scientific advances. The will of the Swedish chemist Alfred Nobel, the inventor of dynamite, established the prizes in 1895...
for chemistry in 1966. He received the Priestley Medal
Priestley Medal
The Priestley Medal is the highest honor conferred by the American Chemical Society and is awarded for distinguished service in the field of chemistry. Established in 1922, the award is named after Joseph Priestley, the discoverer of oxygen who immigrated to the United States of America in 1794...
in 1983.
Early years
Mulliken was born in Newburyport, MassachusettsNewburyport, Massachusetts
Newburyport is a small coastal city in Essex County, Massachusetts, United States, 35 miles northeast of Boston. The population was 21,189 at the 2000 census. A historic seaport with a vibrant tourism industry, Newburyport includes part of Plum Island...
. His father, Samuel Parsons Mulliken, was a professor of organic chemistry
Organic chemistry
Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, composition, reactions, and preparation of carbon-based compounds, hydrocarbons, and their derivatives...
at the Massachusetts Institute of Technology
Massachusetts Institute of Technology
The Massachusetts Institute of Technology is a private research university located in Cambridge, Massachusetts. MIT has five schools and one college, containing a total of 32 academic departments, with a strong emphasis on scientific and technological education and research.Founded in 1861 in...
. As a child, Robert Mulliken learned the name and botanical
Botany
Botany, plant science, or plant biology is a branch of biology that involves the scientific study of plant life. Traditionally, botany also included the study of fungi, algae and viruses...
classification of plant
Plant
Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...
s and, in general, had an excellent, but selective, memory. For example, he learned German
German language
German is a West Germanic language, related to and classified alongside English and Dutch. With an estimated 90 – 98 million native speakers, German is one of the world's major languages and is the most widely-spoken first language in the European Union....
well enough to skip the course in scientific German in college, but could not remember the name of his high school German teacher. He also made the acquaintance, while still a child, of the physical chemist Arthur Amos Noyes
Arthur Amos Noyes
Arthur Amos Noyes was a U.S. chemist and educator. He served as the acting president of MIT between 1907 and 1909. He received a PhD. in 1890 at Leipzig under the guidance of Wilhelm Ostwald. Roscoe Gilkey Dickinson was one of his famous students. Noyes served as Professor of Chemistry at the...
.
Mulliken helped with some of the editorial work when his father wrote his four-volume text on organic compound identification, and thus became an expert on organic chemical nomenclature.
Education
In high school in Newburyport, Mulliken followed a scientific curriculum. He graduated in 1913 and succeeded in getting a scholarship to MIT which had earlier been won by his father. Like his father, he majored in chemistryChemistry
Chemistry is the science of matter, especially its chemical reactions, but also its composition, structure and properties. Chemistry is concerned with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds....
. Already as an undergraduate, he did his first publishable research: on the synthesis of organic chlorides. Because he was unsure of his future direction, he included some chemical engineering
Chemical engineering
Chemical engineering is the branch of engineering that deals with physical science , and life sciences with mathematics and economics, to the process of converting raw materials or chemicals into more useful or valuable forms...
courses in his curriculum and spent a summer touring chemical plants in Massachusetts
Massachusetts
The Commonwealth of Massachusetts is a state in the New England region of the northeastern United States of America. It is bordered by Rhode Island and Connecticut to the south, New York to the west, and Vermont and New Hampshire to the north; at its east lies the Atlantic Ocean. As of the 2010...
and Maine
Maine
Maine is a state in the New England region of the northeastern United States, bordered by the Atlantic Ocean to the east and south, New Hampshire to the west, and the Canadian provinces of Quebec to the northwest and New Brunswick to the northeast. Maine is both the northernmost and easternmost...
. He received his B. S.
Bachelor of Science
A Bachelor of Science is an undergraduate academic degree awarded for completed courses that generally last three to five years .-Australia:In Australia, the BSc is a 3 year degree, offered from 1st year on...
degree
Academic degree
An academic degree is a position and title within a college or university that is usually awarded in recognition of the recipient having either satisfactorily completed a prescribed course of study or having conducted a scholarly endeavour deemed worthy of his or her admission to the degree...
in chemistry from MIT in 1917.
Early career
At this time, the United StatesUnited States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
had just entered World War I
World War I
World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...
, and Mulliken took a position at American University
American University
American University is a private, Methodist, liberal arts, and research university in Washington, D.C. The university was chartered by an Act of Congress on December 5, 1892 as "The American University", which was approved by President Benjamin Harrison on February 24, 1893...
in Washington, D.C.
Washington, D.C.
Washington, D.C., formally the District of Columbia and commonly referred to as Washington, "the District", or simply D.C., is the capital of the United States. On July 16, 1790, the United States Congress approved the creation of a permanent national capital as permitted by the U.S. Constitution....
, making poison gas under James B. Conant. After nine months, he was drafted into the Army's Chemical Warfare Service, but continued on the same task. His laboratory techniques left much to be desired, and he was out of service for months with burns. Later he got a bad case of influenza, and was still in the hospital at war's end.
After the war, he took a job investigating the effects of zinc oxide
Zinc oxide
Zinc oxide is an inorganic compound with the formula ZnO. It is a white powder that is insoluble in water. The powder is widely used as an additive into numerous materials and products including plastics, ceramics, glass, cement, rubber , lubricants, paints, ointments, adhesives, sealants,...
and carbon black
Carbon black
Carbon black is a material produced by the incomplete combustion of heavy petroleum products such as FCC tar, coal tar, ethylene cracking tar, and a small amount from vegetable oil. Carbon black is a form of amorphous carbon that has a high surface-area-to-volume ratio, although its...
on rubber
Rubber
Natural rubber, also called India rubber or caoutchouc, is an elastomer that was originally derived from latex, a milky colloid produced by some plants. The plants would be ‘tapped’, that is, an incision made into the bark of the tree and the sticky, milk colored latex sap collected and refined...
, but quickly decided that this was not the kind of chemistry he wanted to pursue. So in 1919 he entered the Ph.D.
Doctor of Philosophy
Doctor of Philosophy, abbreviated as Ph.D., PhD, D.Phil., or DPhil , in English-speaking countries, is a postgraduate academic degree awarded by universities...
program at the University of Chicago
University of Chicago
The University of Chicago is a private research university in Chicago, Illinois, USA. It was founded by the American Baptist Education Society with a donation from oil magnate and philanthropist John D. Rockefeller and incorporated in 1890...
.
Graduate and early postdoctoral education
He got his doctorate in 1921 based on research into the separation of isotopeIsotope
Isotopes are variants of atoms of a particular chemical element, which have differing numbers of neutrons. Atoms of a particular element by definition must contain the same number of protons but may have a distinct number of neutrons which differs from atom to atom, without changing the designation...
s of mercury
Mercury (element)
Mercury is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver or hydrargyrum...
by evaporation
Evaporation
Evaporation is a type of vaporization of a liquid that occurs only on the surface of a liquid. The other type of vaporization is boiling, which, instead, occurs on the entire mass of the liquid....
, and continued in his isotope separation by this method. While at Chicago
Chicago
Chicago is the largest city in the US state of Illinois. With nearly 2.7 million residents, it is the most populous city in the Midwestern United States and the third most populous in the US, after New York City and Los Angeles...
, he took a course under the Nobel Prize-winning physicist
Nobel Prize in Physics
The Nobel Prize in Physics is awarded once a year by the Royal Swedish Academy of Sciences. It is one of the five Nobel Prizes established by the will of Alfred Nobel in 1895 and awarded since 1901; the others are the Nobel Prize in Chemistry, Nobel Prize in Literature, Nobel Peace Prize, and...
Robert A. Millikan, which exposed him to the old quantum theory
Old quantum theory
The old quantum theory was a collection of results from the years 1900–1925 which predate modern quantum mechanics. The theory was never complete or self-consistent, but was a collection of heuristic prescriptions which are now understood to be the first quantum corrections to classical mechanics...
. He also became interested in strange molecules after exposure to work by Hermann I. Schlesinger on diborane
Diborane
Diborane is the chemical compound consisting of boron and hydrogen with the formula B2H6. It is a colorless gas at room temperature with a repulsively sweet odor. Diborane mixes well with air, easily forming explosive mixtures. Diborane will ignite spontaneously in moist air at room temperature...
.
At Chicago, he had received a grant from the National Research Council
United States National Research Council
The National Research Council of the USA is the working arm of the United States National Academies, carrying out most of the studies done in their names.The National Academies include:* National Academy of Sciences...
(NRC) which had paid for much of his work on isotope separation. The NRC grant was extended in 1923 for two years so he could study isotope effects on band spectra of such diatomic molecules as boron nitride (BN) (comparing molecules with B10 and B11). He went to Harvard University
Harvard University
Harvard University is a private Ivy League university located in Cambridge, Massachusetts, United States, established in 1636 by the Massachusetts legislature. Harvard is the oldest institution of higher learning in the United States and the first corporation chartered in the country...
to learn spectrographic technique from Frederick A. Saunders and quantum theory from E. C. Kemble. At the time, he was able to associate with many future luminaries, including J. Robert Oppenheimer, John H. Van Vleck, and Harold C. Urey. He also met John C. Slater
John C. Slater
John Clarke Slater was a noted American physicist who made major contributions to the theory of the electronic structure of atoms, molecules and solids. This work is of ongoing importance in chemistry, as well as in many areas of physics. He also made major contributions to microwave electronics....
, who had worked with Niels Bohr
Niels Bohr
Niels Henrik David Bohr was a Danish physicist who made foundational contributions to understanding atomic structure and quantum mechanics, for which he received the Nobel Prize in Physics in 1922. Bohr mentored and collaborated with many of the top physicists of the century at his institute in...
.
In 1925 and 1927, Mulliken traveled to Europe, working with outstanding spectroscopists and quantum theorists such as Erwin Schrödinger
Erwin Schrödinger
Erwin Rudolf Josef Alexander Schrödinger was an Austrian physicist and theoretical biologist who was one of the fathers of quantum mechanics, and is famed for a number of important contributions to physics, especially the Schrödinger equation, for which he received the Nobel Prize in Physics in 1933...
, Paul A. M. Dirac
Paul Dirac
Paul Adrien Maurice Dirac, OM, FRS was an English theoretical physicist who made fundamental contributions to the early development of both quantum mechanics and quantum electrodynamics...
, Werner Heisenberg
Werner Heisenberg
Werner Karl Heisenberg was a German theoretical physicist who made foundational contributions to quantum mechanics and is best known for asserting the uncertainty principle of quantum theory...
, Louis de Broglie, Max Born
Max Born
Max Born was a German-born physicist and mathematician who was instrumental in the development of quantum mechanics. He also made contributions to solid-state physics and optics and supervised the work of a number of notable physicists in the 1920s and 30s...
, and Walther Bothe
Walther Bothe
Walther Wilhelm Georg Bothe was a German nuclear physicist, who shared the Nobel Prize in Physics in 1954 with Max Born....
(all of whom eventually received Nobel Prizes) and Friedrich Hund
Friedrich Hund
Friedrich Hermann Hund was a German physicist from Karlsruhe known for his work on atoms and molecules.Hund worked at the Universities of Rostock, Leipzig, Jena, Frankfurt am Main, and Göttingen....
, who was at the time Born's assistant. They all, as well as Wolfgang Pauli
Wolfgang Pauli
Wolfgang Ernst Pauli was an Austrian theoretical physicist and one of the pioneers of quantum physics. In 1945, after being nominated by Albert Einstein, he received the Nobel Prize in Physics for his "decisive contribution through his discovery of a new law of Nature, the exclusion principle or...
, were developing the new quantum mechanics
Quantum mechanics
Quantum mechanics, also known as quantum physics or quantum theory, is a branch of physics providing a mathematical description of much of the dual particle-like and wave-like behavior and interactions of energy and matter. It departs from classical mechanics primarily at the atomic and subatomic...
that would eventually supersede the old quantum theory. Mulliken was particularly influenced by Hund, who had been working on quantum interpretation of band spectra of diatomic molecules, the same spectra which Mulliken had investigated at Harvard. In 1927 Mulliken worked with Hund and as a result developed his molecular orbital
Molecular orbital
In chemistry, a molecular orbital is a mathematical function describing the wave-like behavior of an electron in a molecule. This function can be used to calculate chemical and physical properties such as the probability of finding an electron in any specific region. The term "orbital" was first...
theory, in which electrons are assigned to states that extend over an entire molecule. In consequence, molecular orbital theory was also referred to as the Hund-Mulliken theory.
Early scientific career
From 1926 to 1928, he taught in the physicsPhysics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...
department at New York University
New York University
New York University is a private, nonsectarian research university based in New York City. NYU's main campus is situated in the Greenwich Village section of Manhattan...
(NYU). This was his first recognition as a physicist; though his work had been considered important by chemists, it clearly was on the borderline between the two sciences and both would claim him from this point on. Then he returned to the University of Chicago as an associate professor of physics, being promoted to full professor in 1931. He would ultimately hold a position jointly in both the physics and chemistry departments. At both NYU and Chicago, he continued to refine his molecular-orbital theory.
Up to this point, the primary way to calculate the electronic structure of molecules was based on a calculation by Walter Heitler
Walter Heitler
Walter Heinrich Heitler was a German physicist who made contributions to quantum electrodynamics and quantum field theory...
and Fritz London
Fritz London
Fritz Wolfgang London was a German theoretical physicist. His fundamental contributions to the theories of chemical bonding and of intermolecular forces are today considered classic and are discussed in standard textbooks of physical chemistry.With his brother Heinz, he made a significant...
on the hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
molecule (H2) in 1927. With the conception of hybridized atomic orbitals by John C. Slater
John C. Slater
John Clarke Slater was a noted American physicist who made major contributions to the theory of the electronic structure of atoms, molecules and solids. This work is of ongoing importance in chemistry, as well as in many areas of physics. He also made major contributions to microwave electronics....
and Linus Pauling
Linus Pauling
Linus Carl Pauling was an American chemist, biochemist, peace activist, author, and educator. He was one of the most influential chemists in history and ranks among the most important scientists of the 20th century...
, which rationalized observed molecular geometries, the method was based on the premise that the bonds
Chemical bond
A chemical bond is an attraction between atoms that allows the formation of chemical substances that contain two or more atoms. The bond is caused by the electromagnetic force attraction between opposite charges, either between electrons and nuclei, or as the result of a dipole attraction...
in any molecule could be described in a manner similar to the bond in H2, namely, as overlapping atomic orbitals centered on the atoms involved. Since it corresponded to chemists' ideas of localized bonds between pairs of atoms, this method (called the Valence-Bond (VB) or Heitler-London-Slater-Pauling (HLSP) method), was very popular. However, particularly in attempting to calculate the properties of excited states (molecules that have been excited by some source of energy), the VB method does not always work well. With its description of the electron wave functions in molecules as delocalized molecular orbitals that possess the same symmetry as the molecule, Hund and Mulliken's molecular-orbital method, including contributions by John Lennard-Jones
John Lennard-Jones
Sir John Edward Lennard-Jones KBE, FRS was a mathematician who was a professor of theoretical physics at Bristol University, and then of theoretical science at Cambridge University...
, proved to be more flexible and applicable to a vast variety of types of molecules and molecular fragments, and has totally eclipsed the valence-bond method. As a result of this development, he received the Nobel Prize in Chemistry in 1966.
Mulliken became a member of the National Academy of Sciences
United States National Academy of Sciences
The National Academy of Sciences is a corporation in the United States whose members serve pro bono as "advisers to the nation on science, engineering, and medicine." As a national academy, new members of the organization are elected annually by current members, based on their distinguished and...
in 1936, the youngest member in the organization's history, at that time.
Mulliken population analysis is named after him, a method of assigning charges to atoms in a molecule.
Family
On December 24, 1929, he married Mary Helen von Noé, daughter of a geologyGeology
Geology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates...
professor at the University of Chicago. They had two daughters.
Later years
In 1934, he derived a new scale for measuring the electronegativityElectronegativity
Electronegativity, symbol χ , is a chemical property that describes the tendency of an atom or a functional group to attract electrons towards itself. An atom's electronegativity is affected by both its atomic number and the distance that its valence electrons reside from the charged nucleus...
of elements. This does not entirely correlate with the scale of Linus Pauling
Linus Pauling
Linus Carl Pauling was an American chemist, biochemist, peace activist, author, and educator. He was one of the most influential chemists in history and ranks among the most important scientists of the 20th century...
, but is generally in close correspondence.
In World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
, from 1942 to 1945, Mulliken directed the Information Office for the University of Chicago's Plutonium
Plutonium
Plutonium is a transuranic radioactive chemical element with the chemical symbol Pu and atomic number 94. It is an actinide metal of silvery-gray appearance that tarnishes when exposed to air, forming a dull coating when oxidized. The element normally exhibits six allotropes and four oxidation...
project. Afterward, he developed mathematical formulas to enable the progress of the molecular-orbital theory.
In 1952 he began to apply quantum mechanics
Quantum mechanics
Quantum mechanics, also known as quantum physics or quantum theory, is a branch of physics providing a mathematical description of much of the dual particle-like and wave-like behavior and interactions of energy and matter. It departs from classical mechanics primarily at the atomic and subatomic...
to the analysis of the reaction between Lewis
Gilbert N. Lewis
Gilbert Newton Lewis was an American physical chemist known for the discovery of the covalent bond , his purification of heavy water, his reformulation of chemical thermodynamics in a mathematically rigorous manner accessible to ordinary chemists, his theory of Lewis acids and...
acid
Acid
An acid is a substance which reacts with a base. Commonly, acids can be identified as tasting sour, reacting with metals such as calcium, and bases like sodium carbonate. Aqueous acids have a pH of less than 7, where an acid of lower pH is typically stronger, and turn blue litmus paper red...
and base
Base (chemistry)
For the term in genetics, see base A base in chemistry is a substance that can accept hydrogen ions or more generally, donate electron pairs. A soluble base is referred to as an alkali if it contains and releases hydroxide ions quantitatively...
molecule
Molecule
A molecule is an electrically neutral group of at least two atoms held together by covalent chemical bonds. Molecules are distinguished from ions by their electrical charge...
s. (See Acid-base reaction theories
Acid-base reaction theories
An acid–base reaction is a chemical reaction that occurs between an acid and a base. Several concepts that provide alternative definitions for the reaction mechanisms involved and their application in solving related problems exist...
.) He became Distinguished Professor of Physics and Chemistry in 1961 and continued in his studies of molecular structure
Molecular structure
The molecular structure of a substance is described by the combination of nuclei and electrons that comprise its constitute molecules. This includes the molecular geometry , the electronic properties of the...
and spectra
Spectroscopy
Spectroscopy is the study of the interaction between matter and radiated energy. Historically, spectroscopy originated through the study of visible light dispersed according to its wavelength, e.g., by a prism. Later the concept was expanded greatly to comprise any interaction with radiative...
, ranging from diatomic molecules to large complex aggregates. He retired in 1985.
He died of congestive heart failure at his daughter's home in Arlington, Virginia (across the Potomac River
Potomac River
The Potomac River flows into the Chesapeake Bay, located along the mid-Atlantic coast of the United States. The river is approximately long, with a drainage area of about 14,700 square miles...
from Washington, D.C.
Washington, D.C.
Washington, D.C., formally the District of Columbia and commonly referred to as Washington, "the District", or simply D.C., is the capital of the United States. On July 16, 1790, the United States Congress approved the creation of a permanent national capital as permitted by the U.S. Constitution....
) on October 31, 1986. His body was returned to Chicago
Chicago
Chicago is the largest city in the US state of Illinois. With nearly 2.7 million residents, it is the most populous city in the Midwestern United States and the third most populous in the US, after New York City and Los Angeles...
for burial.
External links
- Key Participants: Robert Mulliken - Linus Pauling and the Nature of the Chemical Bond: A Documentary History