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Marguerite Perey

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Marguerite Catherine Perey was a pioneering French physicist. She specialized in radiochemistry, which is the study of radioactive elements. Her work led to the discovery of a new element in nature. This discovery changed how scientists understood the periodic table. Perey also broke significant barriers for women in the scientific community. She eventually became a leader in nuclear chemistry research.

In 1929, Perey began her career at the Radium Institute in Paris. She worked as a personal assistant and technician to Marie Curie. For ten years, Perey focused on the element actinium. She spent this decade sifting actinium out of uranium ore. This process allowed Curie to study how the element decayed. After Curie died, Perey was promoted to the role of radiochemist. She continued this important research alongside André-Louis Debierne.

In 1935, Perey began investigating a scientific mystery. She read a paper about beta particles emitted by actinium. These particles are a type of radiation emitted by certain atoms. Perey was skeptical of the reported energy levels. She theorized that actinium was decaying into a different element. This new element was what actually produced the observed radiation. She believed this unknown element was a "daughter atom" of actinium.

To test her theory, Perey isolated extremely pure actinium. She studied its radiation very closely and quickly. She detected a small amount of alpha radiation. An alpha particle consists of two protons and two neutrons. When an atom loses these particles, its identity changes. Actinium has 89 protons. By losing an alpha particle, it becomes element 87. This was the element Perey had predicted.

On January 9, 1939, the discovery was officially announced. Jean Baptiste Perrin presented the findings to the Académie des Sciences. He presented a note titled "On an element 87, derived from actinium." Perey did not announce it herself because she lacked a university degree. She named the new element francium to honor France. Francium is an alkali metal in Group 1 of the periodic table. It was the last element to be discovered in nature.

Francium is an incredibly rare substance. Only about 550 grams exist in the Earth's crust at any time. This makes it the second rarest element after astatine. Perey continued her education to advance her career. She earned a Doctorate of Physics from the Sorbonne in 1946. Later, she became the head of nuclear chemistry at the University of Strasbourg. She founded a laboratory that became the Laboratory of Nuclear Chemistry.

In 1962, Perey achieved a historic milestone. She was the first woman elected to the French Académie des Sciences. This was an honor that her mentor, Marie Curie, was never granted. Perey received many prestigious awards during her life. These included the Wilde Prize and the Le Conte Prize. She was also named an Officier of the Légion d'Honneur. Her legacy includes her work on safety for scientists.

Despite her many successes, Perey faced personal challenges. She hoped francium could help diagnose cancer in patients. However, she discovered that francium itself is carcinogenic. This means it can cause cancer. Perey developed bone cancer and died on May 13, 1975. She was 65 years old. Today, her laboratory notebooks and papers are kept in the archives at Strasbourg. Her life remains an inspiration for women in STEM.

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