Unfortunately, the Curies died young. Pierre Curie was killed in a street accident and Marie died of aplastic anemia, almost certainly a result of radiation exposure. Ernest Rutherford (1871-1937) Contributions: Ernest Rutherford is considered the father of nuclear physics. With his gold foil experiment he was able to unlock the mysteries of the atomic structure. He received the noble prize in chemistry in 1908. In 1909 at the University of Manchester, Rutherford was bombarding a piece of gold foil with Alpha particles. Rutherford noted that although most of the particles went straight through the foil, one in every eight thousand was deflected back. "It was as if you fired a fifteen inch naval shell at a piece of tissue paper and the shell came right back and hit you," Rutherford said. He concluded that though an atom consists of mostly empty space, most of its mass is concentrated in a very small positively charged region known as the nucleus, while electrons buzz around on the outside. Rutherford was also able to observe that radioactive elements underwent a process of decay over time which varied from element to element. With the intention of further advancing the study of x-rays, Becquerel intended to place the concealed photographic paper in the sunlight and observe what transpired. Unfortunately, he had to delay his experiment because the skies over Paris were overcast. He placed the wrapped plates into a dark desk drawer. After a few days Becquerel returned to his experiment unwrapping the photographic paper and developing it, expecting only a light imprint from the salts. Instead, the salts left very distinct outlines in the photographic paper suggesting that the salts, regardless of lacking an energy source, continually fluoresced. What Becquerel had discovered was radioactivity. Further investigation showed that the activity of uranium compounds depended upon the amount of uranium present and that radioactivity was not a result of the interactions between molecules, but rather came from the atom itself. Using Pitchblende and chalcolite Curie found that Thorium was radioactive as well. She later discovered two new radioactive elements: Radium and Polonium which took her several years since these elements are difficult to extract and extremely rare. Unfortunately, the Curies died young. Pierre Curie was killed in a street accident and Marie died of aplastic anemia, almost certainly a result of radiation exposure. Ernest Rutherford (1871-1937) Contributions: Ernest Rutherford is considered the father of nuclear physics. With his gold foil experiment he was able to unlock the mysteries of the atomic structure. He received the noble prize in chemistry in 1908. In 1909 at the University of Manchester, Rutherford was bombarding a piece of gold foil with Alpha particles. Rutherford noted that although most of the particles went straight through the foil, one in every eight thousand was deflected back. "It was as if you fired a fifteen inch naval shell at a piece of tissue paper and the shell came right back and hit you," Rutherford said. He concluded that though an atom consists of mostly empty space, most of its mass is concentrated in a very small positively charged region known as the nucleus, while electrons buzz around on the outside. Rutherford was also able to observe that radioactive elements underwent a process of decay over time which varied from element to element. In 1919, Rutherford used alpha particles to transmutate one element (Oxygen) into another element (Nitrogen). Papers at the timed called it "splitting the atom." What They Had Discovered: We now have the essentials to utilize radioactive elements. Roentgen gave us x-rays, Becquerel discovered radioactivity, the Curies were able to discover which elements were radioactive, and Rutherford brought about transmutation and the "splitting of the atom." All of these discoveries and curiosity came with a price. Time showed the damaging effects of radiation exposure and the incredible destruction that could be harnessed from these elements. Applications Radioactive isotopes are presently used in many aspects of human life today. Most people recognize radioactivity's contributions to industry, research and war, but it is even used within many peoples homes. Here are a few examples of how radioactive isotopes are utilized today. Even when regulated properly, the waste can cause contamination which lasts for many years and destroys natural resources. For more information and a specific example go to: www.world-nuclear.org/info/ch...byl/inf07.html Industry Gamma Sterilization Large scale gamma irradiation is used to sterilize disposable medical supplies such as syringes, gloves and other instruments that would be damaged by heat sterilization. Large scale gamma irradiation is also used for killing parasites found in wool, wood and other widely distributed products. In the 1960's the irradiation of meat was allowed by the US, and it is now a commonly used food sterilization method. Many more people died in the months following the bombing due to radiation poisoning, and years later, birth defects would prove the effects of radioactive bombardment upon DNA. A good resource on the industrial and medical uses of radioactive isotopes: www.world-nuclear.org/info/inf56.htm List of Radioactive Elements All of the naturally occuring radioactive elements are concentrated between atomic numbers 84 and 118 on the periodic table, though Tc and Pm are an exception. Also note that there is a break between 110 and 118 on the table, which are suspected radioactive elements that have yet to be discovered. 29 radioactive elements have been identified by scientists to date: Technetium (TC)- Transition metal Promethium (Pm)- Rare earth metal Polonium (Po)- Metalliod Astatine (At)- Halogen Radon (Rn)- Noble gas Francium (Fr)- Alkali Metal Radium (Ra)- Alkali Earth Metal Actinium (Ac)- Rare Earth metal Thorium