Marie Curie’s discovery and isolation of the radium with her husband Pierre Curie between 1898 and 1902 appears to be a very interesting story. “Marie Curie is, of all celebrated beings, the only one whom fame has not corrupted,” said Albert Einstein. Marie Carie Cancer Care, founded in 1948, further immortalized her name. The complex interaction she created between physics and chemistry alongside specific observations, skillful thinking, cutting-edge technology, brute force methods, extreme dedication, and luck factors led Marie Curie to be honored with two Nobel Prizes, the first in physics in 1903 and the second in chemistry in 1911.
Who was Marie Curie (Manya Sklodowska)?
Growing up in Warsaw has a huge share in its success. Warsaw, the birthplace of Manya Sklodowska (Marie Curie’s name before marriage), remained under the strict rule of Russia throughout her youth. Many members of the Sklodowska family embarked against the regime. Manya’s parents and teachers were prominent members of the unarmed, intellectual resistance. In her autobiography, Curie recalls that Russian instructors often treat Polish students as enemies.
The Polish patriotic fire that Manya acquired on this occasion was also the element that would define her whole career and instilled her character, consisting of determination to succeed, passion for knowledge, and moral beliefs. At the age of 10, her mother died of tuberculosis. “Thanks to her father she lived in an intellectual atmosphere of rare quality known to few girls of her age,” wrote Marie’s second daughter Eve Curie.
After graduating from school with a gold medal, Manya faced the lack of higher education options for women and the need to earn her living. Eventually, she accepted the job of the governess for 3.5 years. The money she earned was going to her older sister who studied medicine in Paris, and once her sister started to stand on her own feet, Manya followed her steps.
A quality and challenging education
In 1891, she became one of the 23 female students enrolled in the Sorbonne Faculty of Science, in France. But in her words about her student years, she never mentioned that her education took place in a male-dominated academic world. Also, Marie Curie never supported feminist initiatives that wanted her to exemplify herself to other women.
After three years of hard training, she passed the license es sciences exam in the first place and the license es mathematiques exam in the second place. One of the professors introduced her to Pierre Curie who was already respected by his work on pressure electricity–or piezoelectricity, the electrical charge collected in certain solids such as crystals, ceramics, and bones–and the effect of temperature on magnetism, hoping there might be opportunities for Marie to continue her research.
The similarity in her past experiences in Poland and France was striking. They got married in 1895 and started working together after their first child (who would later win the Nobel) Irene’s birth in 1897. In the later years, their handwritings in the laboratory notebooks follow each other. The couple did not only have a constant exchange of ideas between them but there was also an “energy exchange”, says Henri Poincare, “the definitive remedy for the temporary discourages that every researcher faces.”
Henri Becquerel and uranium radiation
Henri Becquerel discovered uranium radiation in Paris in 1896 as he examined Wilhelm Röntgen’s recent discovery of the radiant effects of on X-rays and certain substances. Becquerel took two thick black papers wrapped around the raw photographic plate, and placed on them some light-emitting minerals in a thin crystal layer, then left the plates in the bright sun for hours. He believed that both sunlight and fluorescence would not affect the plate due to paper, but any “invisible fluorescence” could be detected in the plate as dark spots.
Using the uranium salt, he discovered that the paper passed the glow from the mineral: Part of the photo plate was blurred with the dark silhouette of the mineral layer. Therefore, he assumed that sunlight stimulates the spread of invisible rays from uranium. But then the days when the weather was cloudy intervened. Becquerel, in disappointment, took some of the uranium plates he prepared and put them in his drawer in the laboratory.
Later, when he bathed these films, he was in great shock. Contrary to his guess, he did not find very weak shadows from the uranium layer, instead, “the silhouettes appeared too intense, I thought the event was going on in the dark at the moment,” writes Becquerel. He discovered Radioactivity (he would receive the Nobel Prize for Physics with the Curiosities in 1903 for his discovery), but he did not name this phenomenon, nor did he explain it.
Sophisticated testing process
The Curies decided to examine this new radiation phenomenon by subjecting various minerals to as sensitive tests as possible. Becquerel has shown that radioactivity not only affects photo plates but also discharging electrified bodies. To detect this type of ionizing radiation, Pierre designed an extremely sensitive current-measuring device: an electrometer combined with a piezoelectric quartz balance. The tool consisted of a capacitor (ionization chamber), an electrometer to measure the differences in electrical potential, and quartz crystals to produce piezoelectric (pressure electricity).
Piezoelectric crystals have the property of producing very small electrical polarization on the crystal surfaces under mechanical pressure. In this case, the pressure generated by small weights hanging under the crystal produced polarization. The powdered substance to be tested was spread in the form of a thin layer on the bottom tray of the condenser connected to one pole of the 100-volt accumulator. The upper tray was connected to one of the terminals of the electrometer and the other terminal to the top of the quartz crystal. (The bottom of the crystal was grounded to complete the electrical circuit, like the other pole of the accumulator).
While Marie Curie was performing the process, the slow increase in the electric charge in both trays as a result of ionization of the air in the condenser by the radiation of the substance was balanced with the increase in the electric charge produced by gradually adding weight to the quartz crystal. The balance point was determined by an electrometer. This was made of an aluminum sheet hanging on the conductive platinum wire with a small mirror underneath, rotating around its axis; The ray of light falling on the rotating mirror produced a light point on the graduated glass scale. When this point fell to the midpoint of the scale (considered zero), the electric charge of the top tray of the capacitor and the piezoelectric quartz crystals were exactly the same.
The trick was to keep the light spot in the center while the experiment was going on. Marie Curie must be standing still as much as possible while adding weights to the crystals with one hand, starting and stopping the stopwatch with the other hand, and constantly monitoring the light spot with her eyes. T time after the start of the experiment, the Q charge in the capacitor tray was equal to the charge in the crystal. The electric current caused by the radiation was equal to the electric charge per second at that point—ie. Q/T.
In April 1898, Marie Curie reported alone while working: “All the minerals which demonstrate activity contain active elements. Two minerals of uranium, pitchblende (a uranium oxide) and, chalcolite (uranyl copper phosphate) are much more active than uranium itself. This fact is most remarkable, and suggests that these minerals may contain an element much more active than uranium.” While a 52 millionth of a millionth of the chalcolithic amperes found in nature is producing current, 9 millionth of a millionth artificially produced chalcolite ampere is producing current.
Polonium, and radium
Of course, the second step was to try to isolate this unknown element. Although Pierre was a physicist rather than a chemist, he joined Marie full-time in her work. They had guessed that the isolation would take a few weeks. However, it took several years for them, especially Marie, to make it happen. Not only that, the isolation actually determined the flow of Marie’s whole life. With the help of a chemist colleague, the Curies developed a purification method and produced a 400-fold more active substance than uranium.
According to the result of the first chemical analysis and subsequent spectroscopic analysis, the presence of at least two new elements in the pitchblende ore was evident. In July 1898 they called the first element polonium and in December the second element radium. Their common article was titled “On a New Radioactive Substance Contained in Pitchblende”, it was the first scientific use of the term “radioactive“.
After purifying tons of pitchblende with heavy labor, the final product they obtained in 1902 was 0.1 grams—one-fifteenth of a small teaspoon—pure radium chloride. But this amount was enough for Marie to determine the atomic weight of the radium as 225 and to place radium under the barium in the periodic table of Mendeleyev in alkaline earth metals.
Working with chemist Andre Debierne, who discovered the element of actinium in pitchblende in 1899, he turned the radium into pure metal in 1910. Pure radium has become the standard for comparison of other radioactive materials, especially in beam therapy. Physical chemist and Nobel Prize winner Jean Perrin wrote in 1924: “It is not an exaggeration to say today that [isolation of the radium] is the cornerstone on which the entire edifice of radioactivity rests.”
How did Marie Curie die?
Pierre Curie’s death in 1906 as a result of a traffic accident in Paris was a painful blow that cast a shadow on Marie Curie’s life. But she never gave up his dedication to science. She was immediately appointed to replace Pierre as a professor and became the first woman to teach in Sorbonne, where she studied. In 1914, Radium Institute laboratories were completed at the University of Paris under the direction of Marie. It has become the universal center of nuclear physics and chemistry over time. Irene and Frederic Joliot-Curie made their artificial radioactivity discoveries here in 1934.
The applications of radioactivity in medicine were made Marie increasingly busy; During the First World War, she became the head of the French Radiology Service and even drove an ambulance carrying the x-ray machine to the frontlines. She died of leukemia in a sanatorium in Haute-Savoire, at a relatively early age of 67. Which was undoubtedly due to her exposition to high amounts of radioactive substances over the years.
Marie Curie quotes
- “Nothing in life is to be feared, it is only to be understood. Now is the time to understand more, so that we may fear less.”
- “All my life through, the new sights of Nature made me rejoice like a child.”
- “There are sadistic scientists who hurry to hunt down errors instead of establishing the truth.”
- “Life is not easy for any of us. But what of that? We must have perseverance and above all confidence in ourselves. We must believe that we are gifted for something and that this thing must be attained.”
- I am among those who think that science has great beauty.”