1900-1915

Marie Curie **Discovery: 1903**
 * 1867-1934 **



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Marie Curie was born in Warsaw on November 7, 1867. She was educated by the local schools and by her father in science. She became involved in a student’s revolutionary organization and found it prudent to leave Warsaw. In 1891, she went to Paris to continue her studies at the Sorbonne where she obtained “Licentiateships” in Physics and Mathematical Sciences. After meeting Pierre Curie, who was a Professor in the School of Physics they got married a year later. In 1903, Marie Curie then became Head of the Physics Laboratory at the Sorbonne, and gained her Doctor of Science degree. But in 1906, the tragic death of Pierre Curie occurred and so she took his place as Professor of General Physics in the Faculty of Sciences, the first time a woman had held this position. She was also appointed Director of the Curie Laboratory in the Radium Institute of the University of Paris, founded in 1914. While working with her husband doing research in their very poor and difficult condition laboratory they researched radioactivity. Henri Becquerel inspired this couple due to his discovery of radioactivity in 1896. They discovered isolation of polonium, which was named after the country of Marie’s birth, and radium. Marie Curie developed the methods for separating radium’s from radioactivity residues in sufficient quantities to allow for its characterization and the careful study of its therapeutic properties. In 1929, President Hoover of the United States presented her with a wonderful gift of $50,000 which was donated by American friends of science, to purchase radium for use in the laboratory in Warsaw. She was very flattered by this and she was seen as a high esteem and admiration by scientists throughout the world. She was a member of the Conseil du Physique Solvay from 1911 until death and from 1922 she has been a member of the committee of Intellectual Cooperation of the League of Nations. In 1903, Marie and her husband was awarded half of the Nobel Prize for Physics for their study into the spontaneous radiation discovered by Becquerel, who was awarded the other half of the Prize. In 1911 she received another Nobel Prize for Chemistry for recognition of her work in radioactivity. She also received, jointly with her husband, the Davy Medal of the Royal Society in 1903 and, in 1921, President Harding of the United States, on behalf of the women of America, presented her with one gram of radium in recognition of her service to science. Curie died in Savoy, France, after a short illness, on July 4, 1934.

Marie Curie's poor condition laboratory: []

​ ​Robert Millikan 1868-1953 Discovery:1910 

[] Robert Millikan was born in 1868 in the town of Morrison Illonois, he got his mastership in physics in 1893 and became a professor at the University of Chicago in 1910 and remained there until 1921. Robert Millikan made numerous discorveries including some in the fields of electricity optics and molecular physics. Millikan put an end to all opposition to the atomic and kinetic theories of matter, and also in the early 1920's Millikan worked with the hot spark spectroscopy thus extending the ultraviolet spectrum downwards beyond what was commonly known Robert Millikan's greatest ealrier discovery involved the detection and masurement of the effect of an individual subatomic particle. He did this by using the experiment wich is known as the "oil drop experiment". In this experiment Millikan applied a charge to falling drops of oil and then he created an electric field between the plates thus creating a magnetic field and suspending the drops of oil (which were falling at terminal velocity due to air resistance) in mid-air. Robert Millikan died in 1953 in San Marino California, He was a member of many learned institutions in his country and abroad, and also held honary degrees in some 25 universities.

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Ernest Rutherford 1871-1937 Discovery:1911

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Ernest Ruherford was born in Brightwater, New Zealand. He was a chemist and a physicist who became known as the father of Nuclear Physics. Ernesst studied at Canterbery College, University of New Zealand, and also at the University of Cambridge in England. At one point Ernest held the record for the distance over which electromagnetic waves could be detected. Ernest Rutherford made very important discoveries in the field of radiation. He dicovered and named the three types of radiation alpha,beta, and gamma. Ernest also dicovered the half-life of radioactive materials. Rutherford's discoveries were pivotal in the progress of the Manhattan Project which was the developing of the Nuclear Bomb. Rutherford continued his research on the properties of the radium emanation and of the alpha rays and a method of detecting a single alpha particle and counting the number emitted from radium was devised. In 1910, his investigations into the scattering of alpha rays and the nature of the inner structure of the atom which caused such scattering led to the postulation of his concept of the "nucleus". According to Rutherford the entirty of the the positive charge of the atom was cncentrated at the centre of the atom. He found this out by using his gold foil experiment wwhich he fired radioactive ions at a piece of gold foil and watched them be deflected in different ways.

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Niel Bohr 1885-1965 Discovery:1913  []

Niels Bohr was born on October 7, 1885 and was educated, he worked and even died in Copenhagen, Denmark. While at University of Copenhagen, he studied physics. In 1911 he received his doctorate and then soon traveled to England to study and work under Ernest Rutherford. Bohr began to work on the problem of the atom’s structure. In 1913, Bohr published his theory about the atomic structure based on one of Rutherford’s earlier theories. Rutherford explained how the atom consisted of a positively charged nucleus, with negatively charged electrons in orbit around it. Bohr then took this discovery and expanded on it by proposing that electrons travel only in certain successively larger orbits. He suggested that the outer orbits could hold more electrons then the inner orbits and that the outer orbits determine the atom’s chemical properties. Bohr also discovered that the way atoms emit radiation is by having an electron jump from an outer orbit to an inner one, which would then cause it to emit light. Therefore, in 1913 he discovered how electrons are placed in orbit and how they produce light. In 1916, Bohr became a professor of physics at the University of Copenhagen, which is where he graduated from. Then in 1920, he was named director of the newly constructed Institute of Theoretical Physics at the university. Only two years later he won the Nobel Prize for physics! Bohr was a very warm and respectful man. Once Hitler came into power in Germany, Bohr was concerned for his colleagues and offered a place for many escaping Jewish scientist to live and work. Bohr changed Copenhagen into a refuge. Later Bohr and one out of six sons, named Aage went to the United States, where they both joined the government’s team of physicists working on the atomic bomb at Las Alamos. "An expert is a man who has made all the mistakes which can be made, in a very narrow field."

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Bohr's Model: ​