Linus Pauling

Linus Pauling
Born	Linus Carl Pauling February 28, 1901
Birthplace	Portland, Oregon, U.S.
Died	August 19, 1994 Big Sur, California, U.S.
Nationality	American
Occupation	Chemist, biochemist, peace activist, author
Known for	Chemical bond theory, orbital hybridisation, electronegativity scale, protein structure, nuclear disarmament advocacy
Education	Ph.D., California Institute of Technology
Spouse(s)	Ava Helen Pauling
Children	4
Awards	Nobel Prize in Chemistry (1954), Nobel Peace Prize (1962), National Medal of Science (1974)

Linus Carl Pauling (February 28, 1901 – August 19, 1994) was an American chemist, biochemist, and peace activist whose work fundamentally altered the understanding of the chemical bond and the structure of biological molecules. Born in Portland, Oregon, he rose from modest beginnings to become one of the most influential scientists of the twentieth century. Pauling was awarded the Nobel Prize in Chemistry in 1954 for his research into the nature of the chemical bond and its application to the elucidation of complex substances. Eight years later, he received the Nobel Peace Prize in 1962 for his sustained campaign against nuclear weapons testing, making him one of only a small number of individuals to have received more than one Nobel Prize and the only person in history to have been awarded two unshared Nobel Prizes in different fields. New Scientist named him one of the twenty greatest scientists of all time. Over the course of his career, Pauling published more than 1,200 papers and books, approximately 850 of which addressed scientific topics. He was one of the founders of the fields of quantum chemistry and molecular biology, and his later years were marked by advocacy for orthomolecular medicine and high-dose vitamin C supplementation, claims that did not gain acceptance in the mainstream scientific community.

Early Life

Linus Carl Pauling was born on February 28, 1901, in Portland, Oregon. His father, Herman Henry William Pauling, was a druggist of German descent, and his mother, Lucy Isabelle Darling, was from a family with roots in the region. Herman Pauling operated a pharmacy in various locations around Portland, and the family relocated several times during Linus's childhood. The elder Pauling recognized his son's intellectual curiosity early on, reportedly writing to a local newspaper to ask for reading suggestions for the precocious boy.

Herman Pauling died in 1910 when Linus was only nine years old, leaving the family in financial difficulty. Lucy Pauling struggled to support Linus and his two younger sisters, and the economic hardship of his youth left a lasting impression on the young man. Despite these challenges, Pauling showed an early aptitude for science. As a teenager, he was introduced to chemistry by a friend, Lloyd Jeffress, who had a small home chemistry set. The experience of observing chemical reactions captivated Pauling, and he began collecting chemicals and equipment to conduct his own experiments.

Pauling attended Washington High School in Portland but did not receive his high school diploma at the time of his departure, as he had not completed all the required courses. He instead enrolled at Oregon Agricultural College (now Oregon State University) in Corvallis, Oregon, in 1917, at the age of sixteen. Oregon Agricultural College later awarded him an honorary high school diploma retroactively, decades after he had won his Nobel Prizes.

During his time in Portland and the surrounding area, Pauling took on a variety of odd jobs to help support his family, including working as a delivery boy, a film projector operator, and in other manual labor positions. These early experiences shaped his self-reliance and determination to pursue a career in science despite the financial obstacles he faced.

Education

At Oregon Agricultural College, Pauling pursued studies in chemical engineering, a field that gave him a strong grounding in both chemistry and physics. During his final two years as an undergraduate, Pauling was employed as a full-time teaching assistant in quantitative analysis, an experience that deepened his understanding of chemical methods and also helped him fund his education. He received his Bachelor of Science degree in chemical engineering in 1922.

Pauling then enrolled in graduate studies at the California Institute of Technology (Caltech) in Pasadena, California, where he worked under the supervision of Roscoe Dickinson, who introduced him to the technique of X-ray crystallography. This method of determining the atomic structure of crystals would become one of Pauling's most important research tools throughout his career. Pauling completed his Ph.D. in chemistry with a minor in physics and mathematics in 1925, having already published several significant papers on crystal structures during his graduate studies.

Following his doctorate, Pauling received a Guggenheim Fellowship that allowed him to travel to Europe, where he studied with some of the leading physicists of the era, including Arnold Sommerfeld in Munich, Niels Bohr in Copenhagen, and Erwin Schrödinger in Zurich. These experiences with the founders of quantum mechanics profoundly shaped his approach to chemistry and gave him the theoretical framework he would apply to the study of chemical bonding.

Career

Chemical Bond Theory and Quantum Chemistry

Pauling returned to Caltech in 1927 as an assistant professor of theoretical chemistry and immediately began applying the new quantum mechanical theories to fundamental problems in chemistry. His central achievement during this period was the development of a comprehensive theory of the chemical bond that united quantum physics with classical chemistry.

One of Pauling's most significant contributions was the concept of orbital hybridisation, which explained how atomic orbitals combine and rearrange when atoms form chemical bonds. This theory provided a coherent explanation for molecular geometries that had previously been poorly understood, such as the tetrahedral arrangement of bonds in methane and the planar structure of ethylene.

Pauling also developed the concept of resonance (sometimes called mesomerism), which described molecules whose structure could not be adequately represented by a single Lewis structure but was instead an intermediate or blend of multiple contributing structures. This idea proved essential for understanding the bonding in molecules such as benzene and the carboxylate ion, and it became a foundational concept in organic chemistry.

Another landmark contribution was Pauling's development of the first quantitative electronegativity scale, which assigned numerical values representing the tendency of an atom to attract electrons in a chemical bond. The Pauling electronegativity scale, first published in 1932, remains one of the most commonly used electronegativity scales in chemistry. By providing a systematic way to predict the polarity and ionic character of chemical bonds, this scale transformed how chemists understood molecular properties.

These ideas were brought together in Pauling's seminal book, The Nature of the Chemical Bond and the Structure of Molecules and Crystals: An Introduction to Modern Structural Chemistry, first published in 1939. The book arose in part from a series of lectures Pauling delivered as part of the George Fisher Baker Lectureship at Cornell University, during which he organized and presented his accumulated research on chemical bonding. The Nature of the Chemical Bond became one of the most cited scientific books of the twentieth century and served as a foundational text for generations of chemists.

Pauling's work on chemical bonding extended to a wide range of substances, including metals, ionic crystals, and complex minerals. He used X-ray crystallography extensively to determine the structures of crystals and minerals, publishing numerous papers on the structures of silicates, sulfides, and other inorganic compounds. His set of rules for predicting and rationalizing the crystal structures of ionic compounds, known as Pauling's rules, remain an important tool in mineralogy and solid-state chemistry.

Molecular Biology and Protein Structure

Beginning in the late 1930s, Pauling increasingly turned his attention to biological molecules. He applied the same combination of X-ray crystallography, quantum chemical theory, and physical model building that had proven so successful in his studies of inorganic structures.

One of Pauling's most celebrated discoveries in this area came in 1951, when he and his colleagues Robert Corey and Herman Branson proposed two key structural motifs found in proteins: the alpha helix and the beta sheet. These structures, stabilized by hydrogen bonds between amino acid residues along the protein chain, proved to be fundamental elements of protein secondary structure. Pauling arrived at the alpha helix model through a combination of careful consideration of bond lengths and angles, known from his earlier work on small molecules, and the creative use of physical models. The discovery demonstrated that the three-dimensional shapes of proteins followed from basic chemical principles rather than being arbitrary.

Pauling also made important contributions to the understanding of hemoglobin and the molecular basis of disease. In 1949, he and his collaborators published a groundbreaking paper demonstrating that sickle-cell anemia was caused by a molecular abnormality in hemoglobin, establishing the concept of a "molecular disease." This was one of the first demonstrations that a specific human disease could be traced to a change in a single protein molecule, a finding that had profound implications for genetics and medicine.

Pauling's approach to biological macromolecules—combining X-ray data, model building, and chemical intuition—served as an inspiration for the scientists who subsequently determined the structure of DNA. James Watson, Francis Crick, Rosalind Franklin, and Maurice Wilkins drew on methods and insights that Pauling had pioneered. Pauling himself attempted to solve the structure of DNA and in 1953 proposed a triple-helix model, which proved incorrect. Watson and Crick, working at Cambridge University, soon afterward published their correct double-helix model. Despite missing the correct structure, Pauling's work on proteins and nucleic acids had laid much of the intellectual groundwork for the revolution in molecular biology that followed.

Peace Activism and Nuclear Disarmament

Pauling's political activism began in earnest after World War II, driven by deep concern over the proliferation and testing of nuclear weapons. Along with his wife, Ava Helen Pauling, who was a committed human rights activist, he became an outspoken advocate for nuclear disarmament and international peace.

In the 1950s, Pauling circulated a petition calling for an end to nuclear weapons testing. The petition, which eventually gathered signatures from more than 11,000 scientists from 49 countries, was presented to the United Nations in January 1958. Pauling argued that the radioactive fallout from atmospheric nuclear tests posed a significant threat to human health and to future generations.

His activism brought him into conflict with the United States government during the McCarthy era. Pauling's passport was temporarily revoked in 1952 by the State Department, which suspected him of communist sympathies, and he was called to testify before the Senate Internal Security Subcommittee. Pauling refused to provide the names of those who had helped him circulate the petition, despite the risk of contempt charges.

In 1963, the Partial Nuclear Test Ban Treaty was signed by the United States, the Soviet Union, and the United Kingdom, prohibiting nuclear weapons tests in the atmosphere, outer space, and underwater. On the very day the treaty went into effect—October 10, 1963—the Norwegian Nobel Committee announced that Pauling had been awarded the Nobel Peace Prize for 1962 (which had been reserved the previous year). In his Nobel lecture, delivered on December 11, 1963, Pauling expressed his belief that there would never again be a great world war, given the terrible destructive power of modern weapons, and called for continued efforts to achieve lasting peace through international cooperation.

Pauling's peace activism was controversial within parts of the American scientific establishment, and some colleagues felt that his political engagement detracted from his scientific work. Others, however, viewed his willingness to speak out on moral issues as a reflection of the responsibility that scientists bear for the consequences of their discoveries.

Orthomolecular Medicine and Vitamin C

In the latter decades of his career, Pauling became a prominent advocate for what he termed "orthomolecular medicine"—the idea that optimal health could be achieved by maintaining the right concentrations of substances normally present in the body. His most visible advocacy in this area concerned ascorbic acid, commonly known as Vitamin C, which he believed could prevent and treat a variety of ailments, from the common cold to cancer, when consumed in large doses.

Pauling published the book Vitamin C and the Common Cold in 1970, which became a bestseller and popularized the practice of taking megadoses of Vitamin C. He later collaborated with Ewan Cameron, a Scottish surgeon, on studies that claimed to show benefits of high-dose Vitamin C for cancer patients. However, controlled clinical trials conducted at the Mayo Clinic and other institutions did not replicate these results. The mainstream scientific and medical community did not embrace Pauling's claims regarding the therapeutic benefits of megadose vitamin supplementation, and the topic remained controversial throughout his lifetime and after.

Despite the lack of scientific consensus supporting his views on Vitamin C, Pauling's advocacy brought significant public attention to the role of nutrition in health and contributed to the widespread popularity of vitamin supplements in the United States and elsewhere.

Personal Life

Linus Pauling married Ava Helen Miller on June 17, 1923, while he was still a graduate student at Caltech. Ava Helen Pauling was a fellow Oregonian and became a significant figure in her own right as a human rights activist and advocate for peace. The couple had four children together. Their partnership was both personal and intellectual; Ava Helen's convictions about social justice and disarmament influenced Pauling's own engagement with political causes, and she played an active role in his peace campaigns.

The Paulings remained married for nearly 58 years, until Ava Helen's death on December 7, 1981. Linus Pauling died on August 19, 1994, at his ranch in Big Sur, California, at the age of 93, from prostate cancer.

Pauling maintained a lifelong connection to Oregon. His personal papers and much of his scientific archive are held at Oregon State University, his undergraduate alma mater, where the Linus Pauling Institute continues research in nutrition and health.

In 1969, artist Alice Neel painted a portrait of Pauling, which is held in the collection of the Smithsonian Institution's National Portrait Gallery.

Recognition

Pauling's scientific achievements and humanitarian contributions brought him an extraordinary range of honors over the course of his life. His two Nobel Prizes—the Nobel Prize in Chemistry in 1954 and the Nobel Peace Prize in 1962—placed him in an exclusive category. He remains the only individual to have been awarded two unshared Nobel Prizes, and he is one of only two individuals, along with Marie Curie, to have received Nobel Prizes in two different fields.

In 1974, Pauling received the National Medal of Science from the President of the United States, one of the highest honors bestowed upon American scientists. He was also elected a member of the National Academy of Sciences, the American Academy of Arts and Sciences, and the Royal Society of London, among other scientific organizations.

The American Chemical Society honors Pauling's legacy through the Linus Pauling Medal Award, given by the Portland, Puget Sound, and Oregon local sections of the society. The award recognizes outstanding achievement in chemistry and is one of the most prestigious regional awards in the field.

Oregon State University established the Linus Pauling Institute and maintains extensive archival collections of his papers, correspondence, and research notebooks, which serve as important resources for historians of science.

Legacy

Linus Pauling's contributions to chemistry and molecular biology transformed multiple branches of science. His theory of the chemical bond, including the concepts of hybridisation, resonance, and electronegativity, became standard components of chemistry curricula worldwide and remain central to the modern understanding of molecular structure. The Nature of the Chemical Bond influenced virtually every chemist who studied during the second half of the twentieth century.

In molecular biology, Pauling's elucidation of the alpha helix and beta sheet in protein structure, along with his identification of sickle-cell anemia as a molecular disease, laid foundations for the fields of structural biology and molecular medicine. His model-building approach to macromolecular structure directly inspired the methods used by Watson and Crick to determine the structure of DNA, a discovery that opened the era of modern genetics and biotechnology.

Pauling's peace activism, though controversial in its time, contributed to the international movement that resulted in the Partial Nuclear Test Ban Treaty of 1963, a landmark agreement in arms control. His willingness to risk his reputation and his freedom in the service of nuclear disarmament set an example for subsequent generations of scientist-activists.

His later advocacy for orthomolecular medicine and megadose Vitamin C therapy remains more contested. While his specific claims about the therapeutic value of high-dose vitamins have not been validated by controlled clinical studies, his broader emphasis on the importance of nutrition to health anticipated growing scientific interest in the biochemical basis of disease prevention.

Oregon Public Broadcasting described Pauling as "one of the greatest chemists of the 20th century," a characterization that reflects his standing in the history of science. The breadth of his accomplishments—spanning quantum chemistry, crystallography, molecular biology, and peace advocacy—is matched by few scientists in any era.