Maria Skłodowska-Curie (1867 - 1934)

While exploring a topic for her doctoral research, Maria Skłodowska-Curie became intrigued by Becquerel's studies, which showed that uranium ores emitted novel, then-unknown rays. Unlike ordinary light rays, these could penetrate black paper, discharge an electroscope, and were emitted by uranium salts even after months of storage in darkness. While scientific circles were captivated by the X-rays discovered in 1895, Becquerel's findings sparked little interest. Yet Maria decided to examine Becquerel's rays more thoroughly. In her research, she aimed to leverage the rays' unique ability to discharge an electroscope, though she instead used a precise electrometer to transform qualitative observations into exact quantitative measurements. Examining the rays from uranium and thorium (which exhibited similar properties), she observed another intriguing phenomenon. In minerals containing these elements, the radiation intensity was often far greater than their expected levels in the ores. After extensive trials, Skłodowska-Curie confirmed her results were repeatable— indicating that some unknown, highly radioactive substance must be present in these minerals.

Uranium minerals had been thoroughly studied previously. Skłodowska-Curie knew that any new, unidentified substance, potentially even a new element, would only exist in trace amounts within them. Thus, its activity had to be extraordinarily high. Thus began the painstaking task of hundredsof measurements and chemical experiments, requiring immense precision and accuracy. The Curies separated successive fractions to measure their radioactivity (a term they coined for this unknown property of certain substances). To aid in measurements, they utilized a novel technique in physicochemical analysis, incorporating the piezoelectric effect discovered by Jacques and Pierre Curie.

After several months, the Curies isolated a substance accompanying bismuth from pitchblende (a uranium-rich mineral extracted near Jáchymov in the Czech Republic), which exhibited distinctive chemical traits and was far more active than uranium. On July 18, 1898, the Curie couple announced the discovery of a new element, which they named POLONIUM in honor of Maria's homeland, as she hoped to draw global attention to Poland, divided among occupying powers. Though far from obtaining pure polonium, the researchers discovered another new element in pitchblende during their research. This element was named radium, and its existence was revealed to the world in December 1898. These discoveries were based solely on the radiation properties of these new elements, distinguishing them from bismuth and barium, with which they were mixed in trace amounts. Extracting them in a pure form required tons of radium-bearing material, arduous labor, and significant time. The Curies lacked the necessary funds, laboratory, and assistance for this grueling and physically exhausting work. They handled vast amounts of hydrochloric acid, foul- smelling hydrogen sulfide, ammonia, and other caustic substances. After four years of effort, on March 28, 1902, Maria was able to declare that she had obtained enough radium salt to determine its atomic weight, essential for proving radium as a new chemical element. The sample weighed slightly over 0.1 milligram but had enormous radiation strength. With her characteristic meticulousness and precision, Maria calculated radium's atomic mass several times, arriving at a final value of 225±1. She thus had the scientific proof needed for her discovery of a new element. However, it would be several more years before she succeeded in isolating pure metallic radium.

On June 12, 1903, Maria Skłodowska-Curie defended her doctoral dissertation titled Research on Radioactive Substances, presenting her findings on the newly discovered chemical elements, polonium and radium. These elements marked a significant scientific breakthrough and heralded the dawn of the atomic era. That same year, Maria, alongside her husband Pierre Curie and Henri Becquerel, received the Nobel Prize.

Radium in its pure form was still unknown. Although its salts had been obtained, no one had yet seen a milligram of pure radium. Despite health issues, Maria continued her research, and in 1910, she finally obtained metallic radium. After years of work, she beheld this extraordinary white metal, which emitted mysterious, unknown rays. In 1911, she was awarded her second Nobel Prize, this time in Chemistry, for her contributions to the advancement of chemistry, including the discovery of polonium and radium, the isolation of radium, and her studies of the nature and compounds of this remarkable element.

Biography

Maria Skłodowska-Curie was born on November 7, 1867, in Warsaw, the fifth child in the patriotic Skłodowski family of teachers. Even as a child, Mania (as she was affectionately known) showed an exceptional memory and a wide range of interests. At age eleven, she lost her mother. She completed her secondary education at a government high school in Warsaw at the age of 15, graduating with honors and a gold medal. Though she wished to continue her studies, financial difficulties compelled her to earn a living as a tutor, while she pursued her education independentlyin her spare time. In November 1891, at the age of 24, she traveled to Paris to begin studies at the Faculty of Science of the Sorbonne, as one of 23 women among 1,825 students.

Despite gaps in her preparation, she compensated with diligence and talent, earning a license in physics (licence ès sciences physiques) in 1893, ranking first, and another in mathematics (licence ès sciences mathématiques) in 1894, ranking second. During her vacation in Poland, she sought work in the physical laboratories of Jagiellonian University. Though Professor August Witkowski, then Dean of the Faculty of Philosophy, held her in high regard, he could not offer her even a modest position at the Chair of Physics. Lacking research opportunities in Poland, Skłodowska considered returning to France. When Pierre Curie proposed to her, she hesitated, unsure if she was making the right choice by living away from her homeland and family. Ultimately, in July 1895, Maria became Madame Curie, joining her husband in scientific research.

Pierre Curie focused on studying crystals, while Maria began researching the magnetic properties of steel, publishing her results in 1897. That same year, she gave birth to their daughter, Irène. Balancing scientific work with motherhood, the Curies agreed that she should not abandon her research. Choosing Becquerel’s rays—a little-known topic at the time—for her doctoral work led to her discovery of two new chemical elements, polonium and radium, for which she received two Nobel Prizes.

The lives of the Curies were devoted largely to work, though they attended meetings of the Physical Society and enjoyed family time at home or long bicycle excursions around Paris. Yet they spent most of their time in the laboratory. In the spring of 1906, tragedy struck: on April 19, Pierre Curie was killed by a horse-drawn carriage. This tragic event cast a shadow over Maria's life. Following the funeral, the government offered her a permanent pension, but she declined. She continued to work in the laboratory and prepared to take over Pierre’s lectures, determined to maintain his standards. On November 5, 1906, she became the first woman to give a lecture at the Sorbonne, marking her as the first female professor in the university’s history. Widowed and solitary at nearly forty, Maria found solace in her work. Two years after her husband’s death, she published his collected works. In 1910, she published her lectures, a comprehensive multi-hundred-page work on radioactivity, while also working to establish the laboratory she and Pierre had dreamed of.

In 1910, Skłodowska-Curie, like her husband before her, refused to accept the Legion of Honour despite ministerial insistence. Both were staunchly opposed to receiving any decorations or honorary positions, making an exception only for purely scientific distinctions. For the potential benefits to her laboratory stemming from election to the French Academy of Sciences, Marie reluctantly agreed to put forth her candidacy. However, she ultimately missed a few votes. She then resolved never to reapply, as she found the necessary personal lobbying distasteful.

Her life and work generally evoked deep admiration, though some harbored envy and resentment. In herself, scientific work primarily instilled a sense of humility. Her health, compromised by exposure to radioactive substances in the laboratory, was not in optimal condition. She suffered from kidney issues, radium-burned hands, and her eyesight was also deteriorating. Yet, work always took precedence for this resilient woman; medical treatments and surgeries could wait.

The scientific community awarded her numerous honors and doctorates. Nevertheless, accolades and titles were not what brought her joy. What pleased her greatly was witnessing the growth of the Radium Institute in Paris. War interrupted the work on its establishment. When it broke out, Marie Curie personally transported the radium from her laboratory to Bordeaux to ensure its safety. Uponreturning to Paris, she gathered any useful equipment she could find in labs and storerooms, then began organizing radiological stations staffed by volunteers she had trained. She organized approximately two hundred new or significantly improved radiological centers. In her own lab, she assembled and provided the army with twenty radiological vehicles.

In 1915, the scientist finally established the laboratory — the Radium Institute in a new building on Pierre Curie Street. Between trips to the war fronts, she transported laboratory equipment, accomplishing the work with only a handful of assistants. The new facility conducted radiological courses, where around 150 girls and women were trained over the subsequent years of the war. Unable to serve her true homeland, she served her adopted country as best she could.

After the Great War, the situation in Europe was challenging, and prospects for further research in radioactivity were not particularly promising. Although the radium industry was thriving, with radium commanding a high price, Marie and Pierre Curie had consciously chosen not to patent their discovery, and now she could not afford the radium needed for research. American friends came to her aid, offering her two grams of radium — one in 1921 for the Radium Institute in Paris, and then in 1929 for the Radium Institute in Warsaw, which she also helped establish. The issues concerning Poland remained close to her heart and a subject of constant concern.

Maria Skłodowska-Curie passed away on July 4, 1934, at the Sancellemoz sanatorium due to aplastic anemia. Two days later, without speeches or official delegations, she was laid to rest beside her husband in a family grave in Sceaux, near Paris. On April 20, 1995, the ashes of Maria and Pierre Curie were moved to the Pantheon in Paris, where they joined other esteemed figures honored for their contributions to France. Maria Skłodowska-Curie became the first non-French- born individual, and the first woman, to be thus honored for scientific achievements.

Today, radioactive substances are used in medicine, chemistry, physics, geophysics, and other branches of science and industry. The work of Maria Skłodowska-Curie has been a source of progress, particularly in radiotherapy (through the use of radium, and later artificial radioactive isotopes such as cobalt and iridium), as well as in many other fields. Professor Skłodowska-Curie's achievements in radioactivity marked a milestone in the advancement of science and civilization. It is impossible to list all the honors she received during her life and posthumously. Notably, however, in 2018, readers of the prestigious BBC History Magazine named Maria Skłodowska-Curie the woman who had the greatest impact on world history, and on November 11, 2018, the President of Poland posthumously awarded her the Order of the White Eagle for her contributions to Polish independence.

In conclusion, let us recall the words of Albert Einstein, spoken at a tribute to the scientist in New York in 1935: "When the life of such an extraordinary person as Madame Curie has ended, we should remember its significance for all humankind. The ethical values represented by prominent personalities in each generation have a deeper meaning for that generation and the entire course of history than merely their intellectual achievements."

Alicja Rafalska-Łasocha.