Harold Urey

Harold Urey was a famous science teacher.

He found a special kind of hydrogen. Most hydrogen is very light. His new kind was heavier. This discovery won him a big prize.

He also studied how life might start. He thought certain gases and water could make life. He even looked at rocks from the moon. He loved to learn about space.

Harold Urey was a famous American chemist. He studied how tiny parts of matter work.

Urey is best known for finding a special kind of hydrogen. Most hydrogen is very light. Urey found a heavier version called deuterium. This discovery won him the Nobel Prize in Chemistry in 1934. He found it by carefully warming liquid hydrogen. This helped him separate the heavy atoms from the light ones.

Urey also wondered how life began on Earth. He thought the early air had certain gases. He thought these gases and water could make the building blocks of life. A student of his later proved this in a famous test. This was called the Miller–Urey experiment.

During World War II, Urey helped with a big project. He worked on ways to separate uranium. He led a group that used a way called gaseous diffusion. Later in life, he loved space science. He even studied rocks that came back from the Moon. He was so excited that he offered to go to the Moon himself!

Harold Clayton Urey was a famous American physical chemist. He spent his life studying how tiny parts of matter work.

Urey was born on April 29, 1893, in Walkerton, Indiana. His father was a teacher and a minister. Urey grew up in a religious family that did not support war. Because of this, he worked making TNT during World War I instead of being a soldier. He later earned a PhD at the University of California, Berkeley. There, he studied thermodynamics under a scientist named Gilbert N. Lewis.

Urey is most famous for finding a special kind of hydrogen. Scientists knew hydrogen was very light. Some thought there might be a heavier version, called an isotope. An isotope is a version of an atom that weighs a little more. In 1931, Urey and his partner George Murphy tried to find it. They used a machine called a spectrograph to look at light. They also warmed up liquid hydrogen to separate the atoms. By boiling the liquid, they could make a small amount of heavy hydrogen. They named this discovery deuterium. This work won Urey the Nobel Prize in Chemistry in 1934.

Urey also helped with important work during World War II. He was an expert at separating different isotopes. This was a hard job because the atoms are so similar. He worked on ways to enrich uranium for the Manhattan Project. He led a group at Columbia University to study gaseous diffusion. Gaseous diffusion is a way to separate atoms by letting gas pass through a barrier. This method worked well and was used after the war ended.

Urey wondered how the very first living things began on Earth. He thought the early air had gases like methane and ammonia. He believed these gases and water could create life. One of his students, Stanley L. Miller, tested this idea. This was known as the Miller–Urey experiment.

They used electric sparks to show how amino acids could form. Amino acids are the building blocks that make up life. This helped scientists understand how organic life might start from non-living matter.

In his later years, Urey became very interested in space. He helped start the science faculty at the University of California, San Diego. He even studied rocks that came back from the Moon. These samples arrived at the Lunar Receiving Laboratory from the Apollo 11 mission. Urey was so excited about space that he offered to go to the Moon. He told an astronaut that he would go even if he did not come back. His life showed how studying tiny atoms can help us understand the whole universe.

Harold Clayton Urey was a pioneering American physical chemist. He spent his career investigating the fundamental nature of atoms and molecules. His research focused heavily on isotopes, which are different versions of the same chemical element. These versions have the same number of protons but different numbers of neutrons. This difference gives them different masses. Urey's work helped scientists understand how these tiny variations affect the physical world. His discoveries shaped modern chemistry, nuclear science, and our understanding of how life began.

Urey was born on April 29, 1893, in Walkerton, Indiana. His father, Samuel, was a teacher and a minister. Because his family belonged to a religious sect that opposed war, Urey did not join the army during World War I. Instead, he supported the war effort by working as a chemist making TNT. He later earned his PhD at the University of California, Berkeley. There, he studied thermodynamics, the study of heat and energy, under Gilbert N. Lewis. After his studies, he traveled to Europe to meet famous scientists like Albert Einstein.

In the early 1930s, Urey focused on finding a specific type of hydrogen. Scientists like Raymond Birge and Donald Menzel had predicted a heavy isotope existed. They estimated that only one in 4,500 hydrogen atoms would be heavy. In 1931, Urey and George M. Murphy used a grating spectrograph to look for this atom. A spectrograph is a device that breaks light into a spectrum. They looked for a specific shift in the light lines. Because the heavy atoms were so rare, the signal was very faint.

To find more evidence, Urey used a process called distillation. He knew the heavy isotope would have a higher boiling point than regular hydrogen. He worked with Ferdinand Brickwedde at the National Bureau of Standards to boil liquid hydrogen. By carefully warming the liquid, they could concentrate the heavy atoms. They eventually found that the heavy hydrogen lines were seven times more intense in certain samples. In 1932, they published their discovery of deuterium, which is the name for this heavy hydrogen. This achievement earned Urey the Nobel Prize in Chemistry in 1934.

During World War II, Urey applied his expertise to the Manhattan Project. He was a world expert on isotope separation, which is the process of pulling specific isotopes apart. This was vital for uranium enrichment. Scientists needed to separate uranium-235 from other types of uranium to create nuclear energy. Urey coordinated research on several methods. One method was centrifugal separation, which uses spinning force. Another method was gaseous diffusion, which involves passing gas through a barrier. Urey led a group at Columbia University that successfully developed gaseous diffusion.

Urey also wondered how organic life might have started from non-living matter. He proposed that the early Earth's atmosphere contained ammonia, methane, and hydrogen. He believed these gases could react to form the building blocks of life. His student, Stanley L. Miller, tested this idea in a famous experiment.

The Miller–Urey experiment used electric sparks to simulate lightning in a mixture of these gases and water. The experiment successfully produced amino acids, which are the essential components of living cells. This provided a way to study the chemical origins of life.

In his later years, Urey turned his attention to space science. He helped found the science faculty at the University of California, San Diego. When the Apollo 11 mission returned from the Moon, Urey examined the lunar rock samples. He worked at the Lunar Receiving Laboratory to study these extraterrestrial materials. Urey was so passionate about space that he once told an astronaut he would volunteer for a one-way mission to the Moon. His life's work connected the smallest particles to the largest mysteries of the universe.