Pierre Curie carried a vial of radium in his coat pocket to demonstrate its greenish glow, a habit that caused him to become ill from radiation poisoning well before he was run over by a horse-drawn wagon and killed instantly in 1906. Starting with several tons of pitchblende, the Curies isolated two new radioactive elements after months of work: polonium, which was named for Marie’s native Poland, and radium, which was named for its intense radioactivity. She found that one particular uranium ore, pitchblende, was substantially more radioactive than most, which suggested that it contained one or more highly radioactive impurities. Evolution of atomic theories and applications of atomic energy. Changing Human Understanding of Matter-Timeline of Matter. Marie Curie coined the term radioactivity (from the Latin radius, meaning “ray”) to describe the emission of energy rays by matter. 7th Period Miracle Lerma & RayRay Medrano. Becquerel’s work was greatly extended by Marie Curie (1867–1934) and her husband, Pierre (1854–1906) all three shared the Nobel Prize in Physics in 1903. The second line of investigation began in 1896, when the French physicist Henri Becquerel (1852–1908) discovered that certain minerals, such as uranium salts, emitted a new form of energy. With this information and Thomson’s mass-to-charge ratio, Millikan determined the mass of an electron: Subsequently, the American scientist Robert Millikan (1868–1953) carried out a series of experiments using electrically charged oil droplets, which allowed him to calculate the charge on a single electron. Another set of electrode plates deflect the ray, with the ray bending towards the positive plate. Schematic of cathode ray tube with deflection. model suggested that most of the mass of the atom was inside of the nucleus, and that the rest of the atom was almost completley empty space. Image used with Permission (CC BY-SA-NC). publishes his atomic theory describing the atom as having a central positive nucleus (with a new particle he called the proton) surrounded by negative orbiting electrons. As the cathode rays travel toward the right, they are deflected toward the positive electrode (+), demonstrating that they are negatively charged. \): Deflection of Cathode Rays by an Electric Field.
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