THE CONTRIBUTION OF JÖNS JACOB BERZELIUS TO MORDEN CHEMISTRY

MARIE CURIE:

Akpobome Oghenetega, group 14. Science adviser is Svetlana Kozub.

In 1895 Wilhelm Roentgen discovered the existence of X-rays, though the mechanism behind their production was not yet understood. In 1896 Henri Becquerel discovered that uranium salts emitted rays that resembled X-rays in their penetrating power. He demonstrated that this radiation, unlike phosphorescence, did not depend on an external source of energy but seemed to arise spontaneously from uranium itself. Marie decided to look into uranium rays as a possible field of research for a thesis.

She used an innovative technique to investigate samples. Fifteen years earlier, her husband and his brother had developed a version of the electrometer, a sensitive device for measuring electrical currents. Using Pierre's electrometer, she discovered that uranium rays caused the air around a sample to conduct electricity. Using this technique, her first result was the finding that the activity of the uranium compounds depended only on the quantity of uranium present. She hypothesized that the radiation was not the outcome of some interaction of molecules but must come from the atom itself. This hypothesis was an important step in disproving the ancient assumption that atoms were indivisible.

In 1897 her daughter Irène was born. To support her family, Curie began teaching at the École Normale Supérieureh. The Curies did not have a dedicated laboratory; most of their research was carried out in a converted shed next to the School of Physics and Chemistry. The shed, formerly a medical school dissecting room, was poorly ventilated and not even waterproof. They were unaware of the deleterious effects of radiation exposure attendant on their continued unprotected work with radioactive substances. The School did not sponsor her research, but she would receive subsidies from metallurgical and mining companies and from various organizations and governments.

Curie's systematic studies included two uranium minerals, pitchblende and torbernite. Her electrometer showed that pitchblende was four times as active as uranium itself, and chalcolite, twice as active.

MARIE CURIE

Lilly Awuah, group 21. Science adviser is Olga Levashova.

She was born Maria Salomea Skłodowska in Warsaw, in what was then the Kingdom of Poland, part of the Russian Empire. She studied at Warsaw's clandestine Floating University and began her practical scientific training in Warsaw. In 1891, aged 24, she followed her older sister Bronisława to study in Paris, where she earned her higher degrees and conducted her subsequent scientific work. She shared the 1903 Nobel Prize in Physics with her husband Pierre Curie and with physicist Henri Becquerel. She won the 1911 Nobel Prize in Chemistry.

Her achievements included a theory of radioactivity (a term that she coined), techniques for isolating radioactive isotopes, and the discovery of two elements, polonium and radium. Under her direction, the world's first studies were conducted into the treatment of neoplasms, using radioactive isotopes. She founded the Curie Institutes in Paris and in Warsaw, which remain major centres of medical research today. During World War I, she established the first military field radiological centres.

While a French citizen, Marie Skłodowska Curie never lost her sense of Polish identity. She taught her daughters the Polish language and took them on visits to Poland. She named the first chemical element that she discovered – polonium, which she first isolated in 1898 – after her native country.

Curie died in 1934 at the sanatorium of Sancellemoz (Haute-Savoie), France, due to aplastic anemia brought on by exposure to radiation – mainly, it seems, during her World War I service in mobile x-ray units created by her.

Marie Skłodowska-Curie (7 November 1867 – 4 July 1934) was a Polish and when she was ten years old, Maria began attending the boarding school of J. Sikorska; next she attended a gymnasium for girls, from which she graduated on 12 June 1883 with a gold medal. After a collapse, possibly due to depression, she spent the following year in the countryside with relatives of her father, and the next year with her father in Warsaw, where she did some tutoring. Unable to enroll in a regular institution of higher education because she was female, she and her sister Bronisława became involved with the clandestine Flying University, a Polish patriotic institution of higher learning that admitted women students.