Historical profile Elements of inspiration Unerring in her scientific enquiry and not afraid of hard work, Marie Curie set a shining example for generations of scientists. Bill Griffiths explores the life of a chemical heroine SCIENCE SOURCE / SCIENCE PHOTO LIBRARY LIBRARY PHOTO SCIENCE / SOURCE SCIENCE 42 | Chemistry World | January 2011 www.chemistryworld.org On 10 December 1911, Marie Curie only elements then known to or ammonia, having a water- In short was awarded the Nobel prize exhibit radioactivity. Her samples insoluble carbonate akin to BaCO3 in chemistry for ‘services to the were placed on a condenser plate It is 100 years since and a chloride slightly less soluble advancement of chemistry by the charged to 100 Volts and attached Marie Curie became the than BaCl2 which acted as a carrier discovery of the elements radium to one of Pierre’s electrometers, and first person ever to win for it. This they named radium, and polonium’. She was the first thereby she measured quantitatively two Nobel prizes publishing their results on Boxing female recipient of any Nobel prize their radioactivity. She found the Marie and her husband day 1898;2 French spectroscopist and the first person ever to be minerals pitchblende (UO2) and Pierre pioneered the Eugène-Anatole Demarçay found awarded two (she, Pierre Curie and chalcolite (Cu(UO2)2(PO4)2.12H2O) study of radiactivity a new atomic spectral line from Henri Becquerel had shared the to be more radioactive than pure and discovered two new the element, helping to confirm 1903 physics prize for their work on uranium, so reasoned that they must elements, radium and its status. Since it was much more radiation). Such was Marie’s impact contain other, stronger radioactive polonium radioactive than polonium the on the scientific world – and the constituents. On 12 April 1898 she The pair had to process Curies concentrated their efforts role of women within it – that one presented her findings, writing tonnes of minerals under on it. It was clear that much more of the four stated goals of the 2011 that ‘these minerals may contain an horrific conditions to pitchblende was needed to obtain international year of chemistry is to element which is much more active extract tiny amounts of significant quantities of radium, celebrate the centenary of her prize. than uranium’.1 She and Pierre radium and they eventually obtained some decided that she would concentrate Their daughter, Irène, 8000kg of waste ore from Austria. Early years on the chemical aspects of element also won a Nobel prize They worked for the next four years She was born Maria Salomea separation, while he would study in chemistry, and Marie under appalling conditions in a Sklodowska on 7 November 1867 in their radiation properties. is remembered in the leaking unventilated shed, freezing central Warsaw, Poland. Both her names of universities, in the winter and dreadfully hot by parents were teachers (her mother Polonium and radium institutes, charities and summer. Marie wrote: ‘I had to spend died when Maria was 10) and she was In April 1898, Marie dissolved the element curium a whole day mixing a boiling mass highly motivated and well educated. pitchblende in HCl and treated the with a heavy iron rod nearly as large Poland was then a subject state of solution with H2S; uranium and as myself. I would be broken with Russia and women were excluded thorium remained in solution, but fatigue at the day’s end’. Nevertheless from advanced study, so in 1891 she the precipitated sulfides remained she described life in ‘this miserable joined her sister Bronia in Paris, highly radioactive. After further shed’ as ‘the best and happiest years enrolling at the Paris Sorbonne manipulation this radioactive of our life’, and was much honoured University and taking her physics material was found to co-precipitate when Lord Kelvin and other famous and mathematics degrees with with bismuth. In July she and Pierre scientists visited her there. outstanding grades in 1893–4. She published a paper (coining the word They worked with 20kg batches of met Pierre Curie in the spring of 1894, ‘radio-active’ in its title), presented by pitchblende: grinding, dissolving and and they married in 1895 at a civil Becquerel to the Academy of Sciences refining them to small quantities of ceremony in Sceaux in the Parisian – founded in 1666, this institution was solutions. In 1902 they isolated 0.1g. suburbs. They were both rather as prestigious in France as the Royal of anhydrous RaCl2 after thousands shy and unworldly, caring little for Society in Britain. They suggested, of recrystallisations from the more- material things; their chief recreation for the first time, that radioactivity soluble BaCl2 in HCl, measuring the was cycling, but they shared too a was a phenomenon associated with atomic weight of radium as 225. deep appreciation of science and an the atom, and proposed that the In 1901 Pierre and Becquerel obsessive dedication to it. Their first new element, once its existence published a paper on the daughter Irène was born in 1897. was confirmed, should be called physiological effects of radioactivity, Pierre’s work on piezoelectricity, polonium.2 and Pierre showed, with medical crystal symmetry and magnetism at They realised that pitchblende The Curies isolated collaborators, that radiation from the Municipal School of Industrial must contain yet another highly traces of radium and radium (and subsequently from Physics and Chemistry (EPCI) in radioactive material, not precipitated polonium from tonnes of radon gas which it and other Paris is still fundamentally important, from its solutions by H2S, (NH4)2S pitchblende uranium ore radioactive elements emit) could especially the concepts of the destroy cancerous cells. Curie temperature (above which magnets lose their magnetism) and The physics Nobel prize the Curie law relating magnetism In June 1903 Pierre came to the UK and temperature. Marie published to give a discourse at London’s Royal her first paper in 1897 on the Institution. Many eminent scientists magnetisation of steels but looked were present including Sir William for a new research topic, which she Crookes, Sir Oliver Lodge, Lord found in radioactivity. A year after Kelvin and the physicist William Wilhelm Röntgen’s observation Ayrton. Ayrton’s wife Hilda, a of x-rays in 1895, Henri Becquerel remarkable scientist in her own right, discovered radioactivity of uranium and Marie became firm friends. from photographic plates which, Marie completed her doctoral when wrapped in black paper close to thesis in June 1903. Later the same uranium or its salts, showed images day Ernest Rutherford (himself to when developed. become a chemistry Nobel laureate Marie was allocated a damp in 1908) met the Curies for dinner; room of the EPCI for her doctoral Marie trusted him and they formed research, and showed that among a a lasting friendship. That evening, wide variety of inorganic materials, when Pierre showed him some uranium and thorium were the radium glowing blue in the dark, GRAY THEODORE www.chemistryworld.org Chemistry World | January 2011 | 43 Historical profile SCIENCE PHOTO LIBRARY PHOTO SCIENCE Rutherford noted that Pierre’s Academy of Sciences and in June he Outside of the laboratory, the cobbled Rue Dauphine he was fingertips were raw and inflamed, gave his Nobel lecture in Stockholm. Pierre and Marie were run over by a horse dray and instantly as indeed were Marie’s. Others In December 1905 their second keen cyclists killed. Marie was devastated. He was had observed that both Curies had daughter, Eve Denise, was born. buried in Sceaux and later Marie and burns, which must have arisen her children moved there. from their handling of radium. This Troubled times Marie was given Pierre’s Sorbonne and inhaling radon formed from On 19 April 1906, Marie left the Marie’s mobile x-ray vans chair, thereby becoming the first radium’s decay almost certainly Sorbonne to give the children their brought radiology to the female professor in France. That adversely affected their general lunch; Pierre walked in the rain to front lines in the first year Lord Kelvin wrote to The Times health. After the first world war in meet his publishers. When crossing world war newspaper suggesting that radium particular there were increasing was a compound of lead containing reports of illness and sometimes five helium atoms, but Rutherford deaths amongst those who had robustly disagreed, saying that worked with radium salts for cancer radium fulfilled every test required of therapy, as paints for luminous an element. Marie resolved to prove watches, and in quack ‘cures’ for a that this was so. In 1907 she made host of ailments. 0.4g of RaCl2 and re-determined In November 1903 the Curies and the atomic weight as 226.45. In 1910 Becquerel were awarded the physics she isolated radium as a shiny-white Nobel prize for their work on metal by electrolysing RaCl2 in radioactivity. Becquerel attended the mercury and distilling off the latter Stockholm ceremony, but neither of from the amalgam.3 the Curies went: Pierre was ill and Paul Langevin, a pioneer in overwhelmed with teaching duties magnetochemistry, one-time student and Marie was recovering from a of Pierre and long a friend of the miscarriage. It was a mixed blessing Curies, succeeded Pierre as professor – financially helpful (70 000 francs), of physics and chemistry at the EPCI. but it exposed them to international Although married with four children acclaim and scrutiny. Marie later he was separated and had a small wrote that ‘the overturn of our apartment near Marie’s laboratory voluntary isolation was a cause of where they sometimes met. In 1911 real suffering for us’. his study was burgled, letters from A professorship was created Marie stolen and published.