Harold Urey was an American physicist and chemist whose pioneering work on isotopes brought him to prominence. He led the 1934 discovery of deuterium, a heavy type of hydrogen, for which he was awarded the Nobel Prize in Chemistry. During World War II, he also played a crucial part in the development of the atomic bomb. Urey was born to a teacher in Walkerton, Indiana. Under the tutelage of Gilbert N. Lewis, he studied thermodynamics and earned his Ph.D. in 1923. After receiving his degree, he began his career as a research associate at Johns Hopkins University before becoming an assistant professor of chemistry at Columbia University. Urey discovered deuterium in 1931, at first referring to it as a heavier type of hydrogen. Following this, he became an internationally recognized expert in isotope separation. During World War II, Urey focused his efforts on the separation and enrichment of uranium by gaseous diffusion. After the war, Urey became a professor. At the conclusion of his career, he studied space science and was one of six scientists that examined Apollo 11’s space samples at the Lunar Receiving Laboratory.
Youth and Early Life
Harold Urey was born as Harold Clayton Urey on April 29, 1893, in Walkerton, Indiana to Samuel Clayton Urey and Cora Rebecca née Reinoehl. He was the eldest of the couple’s three children, with two younger siblings, a brother, and a sister. Urey’s father died when he was six years old.
Before enrolling in high school in Kendallville, Indiana, Urey had his elementary education at Amish Grade School. Earlham College awarded him with a teaching certificate.
Urey enrolled at the University of Montana in Missoula in 1914. Three years later, he obtained a Bachelor of Science in Zoology. The US entered World War I the same year. Urey worked for Barrett Chemical Company during World War II, producing TNT.
Harold Urey’s Career
After World War I, he accepted a position as a chemistry professor at the University of Montana. In 1921, he enrolled in a Ph.D. program in thermodynamics at the University of California, Berkeley. The methods he developed for determining thermodynamic parameters from spectroscopic data are now widely used.
After obtaining his Ph.D. in 1923, Urey was awarded a fellowship by the American-Scandinavian Foundation to study under the Danish physicist Niels Bohr at the Niels Bohr Institute in Copenhagen.
Upon his return to the United States, he was offered a fellowship at Harvard University and a research associate position at Johns Hopkins University. He chose option two.
He was named an assistant professor of chemistry at Columbia University in 1929. The next year, Urey collaborated with Arthur Ruark to publish Atoms, Quanta, and Molecules. It was one of the earliest written works on quantum mechanics and its application to atomic and molecular systems.
During the 1930s, the isotopes theory was created. Chemists from all around the world knew that an element might have atoms with the same number of protons but differing masses. While carbon, nitrogen, and oxygen isotopes had been found, the discovery of hydrogen isotopes remained a mystery. Therefore, Urey set out to discover the isotopes of hydrogen.
Urey conducted a series of experiments with colleague chemist Murphy that allowed him to compute the isotopes of hydrogen. He even traveled to the National Bureau of Standards’ cryogenics laboratory in Washington, D.C. to get liquid hydrogen for their tests.
Urey did experimental studies with the aid of Ferdinand Brickwedde and Murphy. He evaporated hydrogen many times. Finally, the group saw Balmer lines for ‘Heavy Hydrogen’ that was seven times more powerful than usual. The confirmation of their discovery of what is now known as deuterium came at that time.
In 1932, Urey, Murphy, and Brickwedde jointly published a paper announcing the discovery of deuterium. He was elevated to Professor at Columbia University in the same year. In addition, he established the Journal of Chemical Physics and served as its inaugural editor until 1940.
The Nobel Prize in Chemistry was awarded to Urey in 1934 for his discovery of heavy hydrogen. From 1940 to 1945, he served as Director of War Research for the Columbia University Atomic Bomb Project.
Urey’s research and the investigation did not end with deuterium. He continued to learn more about the carbon, nitrogen, hydrogen, oxygen, and sulfur isotopes. Continuously developing effective techniques for separating the rarer isotopes of all these elements, he made them readily available for laboratory research.
Prior to the outbreak of World War II, Urey had risen to prominence in the scientific community and was commonly regarded as the world’s foremost authority on isotope separation. Prior to it, he had only worked with lesser elements. In 1939, he released papers that provided insight into the centrifugal separation of heavier isotopes.
When Danish physicist Neil Bohr declared that uranium 235 had the potential to be fissile, his assertion was scrutinized. To dispel skeptics, Urey conducted exhaustive research on uranium. He applied all experimental methods, from gaseous diffusion to thermal diffusion, to determine the outcome.
In 1941, he participated in the uranium study performed by the Office of Scientific Research and Development. The next year, he and George B. Pegram traveled to England to pursue cooperation in the creation of the atomic bomb.
Urey was appointed director of Columbia’s wartime Substitute Alloy Materials Laboratory. In 1943, the Manhattan Project began to gain momentum. As anticipated, the massive and intricate operation was plagued by numerous complications. The creation of a good diffusion barrier for uranium hexafluoride was extraordinarily difficult. The gaseous diffusion approach was favored over centrifugation.
By the end of 1943, Urey supervised a workforce of 700 individuals. The gaseous diffusion method presented its own technical obstacles but was more promising than the alternatives. It was eventually developed successfully and became the only technique utilized in postwar years. The Director of the Manhattan Project, Major General Leslie R. Groves, Jr., awarded Urey the Medal for Merit for his contributions to the Manhattan Project.
After World War II, Urey became a Distinguished Service Professor of Chemistry at the University of Chicago’s Institute for Nuclear Studies. In 1952, he was appointed professor of chemistry at Ryerson.
In 1956 and 1957, he served as the George Eastman Visiting Professor at the University of Oxford. In 1958, he became Professor-at-Large at the University of California.
Post-war, Urey consistently opposed military control of nuclear energy. He supported the establishment of the Atomic Energy Commission. Urey also participated in anti-war lecture tours and became an active participant in congressional nuclear debates.
At the end of his life, Urey devoted himself to planetary science research activities. In his work, ‘The Planets: Their Origin and Development,’ he provided a comprehensive timeline of the origins of the Earth, Moon, meteorites, and solar system. In the Lunar Receiving Laboratory, he was one of the six scientists who examined the lunar samples brought by Apollo 11, which he did alongside five others.
Harold’s Major Opera
Harold Urey is well known as the world’s foremost authority in isotope separation. In the 1930s and 1940s, when he began working on isotope separation, he performed groundbreaking research. The discovery of deuterium, an isotope of hydrogen, was made possible by his meticulous experimental labor.
During World War II, he devoted himself to isotope separation and enrichment of uranium. Using the method of gaseous diffusion, he successfully created the same.
Awards & Achievements
Urey was awarded the Nobel Prize in Chemistry in 1934 for discovering deuterium. He also got the Willard Gibbs Medal from the American Chemical Society in the same year.
He was awarded the Davy Medal by the Royal Society of London in 1940. Three years later, he was honored with the Franklin Medal, and in 1946, he received the Medal of Merit for his contributions to the Manhattan Project.
Urey received three awards in 1954 and 1955: the Cordoza Award, the Honor Scroll Award from the American Institute of Chemists, and the Joseph Priestley Award.
Personal History and Legacy
Urey married Frieda in Lawrence, Kansas, in 1926. In 1927, Gertrude Bessie (Elizabeth) was born, followed by Frieda Rebecca in 1929, Mary Alice in 1934, and John Clayton Urey in 1939.
On January 5, 1981, he passed away in La Jolla, California. He was interred in the DeKalb County, Indiana Fairfield Cemetery.
A lunar impact crater and the asteroid 4716 bear his name.
Estimated Net Worth
Harold is one of the wealthiest and most prominent chemists. According to our research, Wikipedia, Forbes, and Business Insider, Harold Urey has an estimated net worth of $1.5 million.