Abstract
Marie Curie was a physicist, chemist and pioneer in the study of radiation. She and her husband, Pierre, discovered the elements polonium and radium, for which they and Henri Becquerel were awarded the Nobel Prize in Physics in 1903. Marie received the Nobel Prize in Chemistry in 1911.
Born Maria Skłodowska in 1867 in Warsaw, Poland, she was the youngest of five children. After her mother died and her father could no longer support her, she became a governess, reading and studying in her own time to quench her thirst for knowledge.
Up to this point, her lack of money prevented her from attending higher education, but when her sister offered her lodgings in Paris with a view to going to university, she grasped the opportunity and moved to France in 1891. Marie entered Sorbonne University in Paris where she read physics and mathematics, discovering a deep passion for the subjects. It was in Paris, in 1894, that she met Pierre Curie – a scientist working in the city – whom she married a year later.
The Curies became research workers at the School of Chemistry and Physics in Paris, where they began their pioneering work into invisible rays given off by uranium – a new phenomenon which had recently been discovered by Professor Henri Becquerel. He had shown that the rays were able to pass through solid matter, fog and photographic film and caused air to conduct electricity. Marie also noticed that samples of a mineral called pitchblende, which contains uranium ore, were a great deal more radioactive than the pure element uranium.
Marie was convinced she had found a new chemical element, but other scientists doubted her results. Pierre and Marie set about working to search for the unknown element. They ground up samples of pitchblende, dissolved them in acid, and began to separate the different elements present. Eventually, they extracted a black powder 330 times more radioactive than uranium, which they called polonium.
Upon further investigation, the Curies found that the liquid left behind after they had extracted polonium was still extremely radioactive. They realised that pitchblende contained another new element, far more radioactive than polonium, but present in even smaller quantities. In 1898, the Curies published strong evidence supporting the existence of the new element – which they called radium – but they still had no sample of it. Pitchblende is an expensive mineral, because it contains valuable uranium, and Marie needed a lot of it. She got in touch with a factory in Austria that removed the uranium from pitchblende for industrial use and bought several tonnes of the material.
Marie set about processing the pitchblende to extract the tiny quantities of radium. This involved working on a much larger scale than before, with 20kg batches of the mineral – grinding, dissolving, filtering, precipitating, collecting, redissolving, crystallising and recrystallising. The work was heavy and physically demanding – and involved dangers the Curies did not appreciate. During this time, they began to feel sick and physically exhausted; today we can attribute their ill-health to the early symptoms of radiation sickness.
At the time they persevered in ignorance of the risks, often with raw and inflamed hands because they were continually handling highly radioactive material. In 1902, Marie eventually isolated radium as radium chloride, determining its atomic weight. The journey to the discovery had been long and arduous. In 1903, Marie and Pierre were awarded the Nobel Prize for Physics jointly with Henri Becquerel for their combined, though separate, work on radioactivity. In the same year, Marie passed her doctorate thesis in Physics.
In 1906, Marie's life was struck by tragedy when Pierre was killed in a street accident after being knocked down by a horse and cart. Her indomitable spirit, however, kept her working and she went on to succeed him in his Chair as Professor at the Sorbonne, as well as carrying on lecturing where he had left off. Her determination and remarkable endeavours led to a second Nobel Prize in 1911, this time in chemistry, for creating a means of measuring radioactivity.
During the First World War, Marie Curie worked to develop small, mobile X-ray units that could be used to diagnose injuries near the battlefront. As Director of the Red Cross Radiological Service, she toured Paris, asking for money, supplies and vehicles which could be converted. In October 1914, the first machines, known as "Petits Curies", were ready, and Marie set off to the front.
