Marie Curie: Scientific Determination

Written by Emir Taha Macit

Among the many revolutionaries in science and chemistry, few have shaken the world of science as powerfully as Marie Curie. After spending years in a miserable old warehouse working with dangerous chemicals at a time when her homeland was under strict Russian rule, she discovered the radioactive elements polonium and radium and coined the term radioactivity, along with her husband. Through unshakable will and strenuous labor, Marie Curie established herself as a true icon in the world of chemistry, rewriting its laws in both a scientific and societal sense.

She was born in Warsaw on November 7, 1867, under the name Marya Sklodowska. Poland, at the time, was ruled by the Russian Empire. This rule halted cultural progress for Poland and prevented higher education for women, along with many other things. The suppression greatly disturbed the young Marie, who had always considered her education and scientific studies crucial, leading her to move to Paris in pursuit of knowledge at the Sorbonne University. After years of surviving on bread and tea in her dorm, she met her lifelong husband and scientific partner, Pierre Curie. The two went on to turn an abandoned medical school shed into a laboratory, conducting experiments and studies together to earn their respective PhDs. This warehouse, which they transformed to give them more freedom than in college quarters, is where they would go on to make their famous discoveries.

In 1896, Henri Becquerel discovered what he called Uranic Rays, emissions from uranium (U, atomic number 92) salts that could expose photographic plates and ionize the air, stripping it of some of its electrons without requiring external energy. His experiment followed the discovery of X-rays by Wilhelm Conrad Roentgen, and was caused by his curiosity about their possible link to phosphorescence. After discovering the penetrative and darkening effects of uranium salts on photographic plates under even cloudy weather, Becquerel spread the news of his discovery and began further studies. When this news reached Marie, she became determined to expand upon it as a means of constructing her thesis.

She examined various uranium samples in different forms such as dissolved, crystallized, and powdered. Using the Curie piezoelectric electrometer, a special electrometer designed by Pierre and his brother Jacques that could precisely measure slight electrical charges by utilizing piezoelectric quartz and a quadrant electrometer, she was able to discover that the physical state of the matter did not affect the amount of ionization they induced; only the amount of uranium atoms in the sample did. This led to her discovery of atoms’ intrinsic properties of radioactivity- a term she coined- a discovery that went against widespread atomic theories at the time that suggested atoms were solid, unalterable, and required reactions with other atoms to generate energy.

Furthermore, Marie wished to test the radioactivity of other elements to determine if it was unique to uranium, analysing every element in the periodic table at the time to do so. In this stage of testing, she additionally discovered the radioactivity of Thorium (Th, atomic number 90). After going through the periodic table, she set her sights on testing various minerals containing and not containing U or Th to see if being in a natural mixture affected radioactivity. While the readings were expected for minerals such as common rocks and most others containing U or Th, she found anomalies in some of the results, notably pitchblende (U3O8) and torbernite (Cu(UO2)2(PO4)2 · 12H2O). Although they should have been less radioactive than pure uranium of their mass due to their impurity, torbernite was two times as radioactive, and pitchblende was four times as radioactive. This led Marie to hypothesize the possible existence of unknown elements in said minerals and to ask Pierre for help in proving her hypothesis.

They decided on a process to use throughout their experiments, which would last four grueling years, that involved crushing and dissolving tons of pitchblende residue, separating some non-radioactive elements through controlled solidification, and, respectively, fractional precipitation and fractional crystallization to remove minuscule amounts of the mysterious elements from the bismuth and barium. They named the element that clung to bismuth polonium after Marie’s oppressed homeland, and the one that stuck onto barium radium. While polonium had a short half-life of around 138 days that caused it to decay and prevent accumulation during the experiments, radium had a half-life of around 1600 years, providing the Curies with solid findings that glowed in their dark shed.

Their monumental discoveries led them to receive the 1903 Nobel Prize in Physics along with Henri Becquerel, and Marie to receive the 1911 Nobel Prize in Chemistry after further experiments provided additional proof. After Pierre passed away in 1906 from an accident involving a horse wagon, Marie continued their work despite the physical toll it was taking on her body. Prolonged radiation exposure led to her death in 1934 from aplastic anemia. Ultimately, her willpower to continue a study that has reshaped various understandings in science in miserable conditions has earned her the title of the only person to receive Nobel Prizes in two distinct scientific disciplines, and created a legacy that could not be overlooked.

References:

1. (n.d) MARIE CURIE. The Nobel Prize. https://www.nobelprize.org/stories/women-who-changed-science/marie-curie

2. Shanbhag, Nandan M et al. “Marie Curie (1867-1934): Twice Nobel Laureate and Her Enduring Legacy in Radiation Medicine.” Cureus vol. 16,8 e66703. 12 Aug. 2024, doi:10.7759/cureus.66703

3. (n.d.) Uranic Rays. Radioactivity. https://radioactivity.eu.com/articles/phenomenon/uranic_rays

4. Britannica Editors. (2019). pitchblende. Encyclopedia Britannica .https://www.britannica.com/science/pitchblende