On December 26, 1898, in Paris, chemists Marie Curie, Pierre Curie, and Gustave Bémont announced the discovery of two new radioactive elements: radium and polonium. Their findings revealed substances that were approximately 900 times more radioactive than uranium, marking a pivotal moment in the field of chemistry and medicine.
Curie, then a medical student at the Sorbonne, ventured into the study of radiation for her thesis. This decision came shortly after the groundbreaking discoveries of Wilhelm Röntgen in 1895, who unveiled X-rays, and Henri Becquerel in 1896, who found that uranium salts emitted radiation even in darkness. These discoveries paved the way for Curie’s explorations, allowing her to dive into experimental work without the burden of extensive prior literature.
In a cramped storeroom at the Paris Municipal School of Industrial Physics and Chemistry, Curie began her research. With the support of her husband, Pierre, who abandoned his own projects to assist her, they sought to understand the properties of uranium-rich minerals. The couple’s work would soon lead them to pitchblende, a mineral known for its uranium content.
Curie utilized a piezoelectric quartz electrometer, a device invented by her brother-in-law, Jacques Curie, to measure weak electrical currents generated by radioactivity. In her 1904 article for *Century Magazine*, she emphasized her approach: “Instead of making these bodies act upon photographic plates, I preferred to determine the intensity of their radiation by measuring the conductivity of the air exposed to the action of the rays.”
Despite challenges, including a damp working environment that affected her results, Curie discovered that certain minerals exhibited radioactivity far exceeding that of uranium. This led her to conclude that “the ore must contain a substance more radioactive than uranium and thorium,” as she later shared in a 1903 article.
The Curies, alongside Bémont, embarked on a methodical separation of pitchblende to isolate the radioactive elements. By analyzing light spectra, they were able to identify a mineral that was around sixty times more radioactive than uranium, which they named polonium. Shortly thereafter, on December 21, they identified radium, which was a staggering 900 times more radioactive.
The groundbreaking discoveries were presented at the French Academy of Sciences on December 26, 1898. Their work set the stage for future research in radiation and its medical applications, ultimately earning the Curies and Becquerel the Nobel Prize in Physics in 1903. Initially, Marie was overlooked for the award, but Pierre advocated for her inclusion, emphasizing her critical contributions.
In 1911, Curie received a second Nobel Prize, this time in chemistry, recognizing her extensive work on radium. Tragically, Pierre died in 1906, but Marie continued to advocate for the use of X-rays in medicine, including the development of mobile X-ray units for soldiers during World War I.
Her research on radium revealed its potential to target diseased cells more effectively than healthy ones, a principle that would later shape cancer treatment through radiotherapy. Despite the revolutionary impact of her work, both Curies suffered from radiation exposure, leading to health complications. Marie Curie ultimately died from aplastic anemia in 1934, a condition linked to radiation damage to bone marrow.
Today, the notebook Marie used to document her pioneering discoveries remains radioactive and is preserved in a lead-lined box, a testament to her groundbreaking contributions to science and medicine. Through her relentless pursuit of knowledge, Curie’s legacy continues to influence research and therapeutic practices worldwide.
