Rutherford, Ernest Radiations

Rutherford, Ernest. 1913. Radioactive Substances and Their Radiations. Cambridge Cambridge University Press. 

His work, called a classical example of the scientific method, was the second and last of his independent publications. Despite the pleadings of his colleagues, he enlisted in the British Army at the outbreak of World War I, and was killed in battle on August 10, 1915. see also Bohr, Niels Bragg, William Lawrence Lanthanides Radiation Rutherford, Ernest. 

The origin of the rays was initially a mystery, because the existence of the atomic nucleus was unknown at the time. However, in 1898, Ernest Rutherford took the first step to discover their origin when he identified three different types of radioactivity by observing the effect of electric fields on radioactive emissions (Fig. 17.4). Rutherford called the three types a (alpha), (3 (beta), and y (gamma) radiation. 

Ernest Rutherfords proposed atomic structure added to the problems posed to nineteenth century physics by the ultraviolet catastrophe and the photoelectric effect. Rutherfords atom had a negatively charged electron circling a positively charged nucleus. The physics of the day predicted that the atom would emit radiation, causing the electron to lose energy and spiral down into the nucleus. Theory predicted that Rutherfords atom could not exist. Clearly, science needed new ideas to explain these three anomalies. 

Sir Ernest Rutherford (1871-1937 Nobel Prize for chemistry 1908, which as a physicist he puzzled over) was a brilliant experimentalist endowed with an equal genius of being able to interpret the results. He recognized three types of radiation (alpha, beta, and gamma). He used scattering experiments with alpha radiation, which consists of helium nuclei, to prove that the atom is almost empty. The diameter of the atomic nucleus is about 10 000 times smaller than the atom itself. Furthermore, he proved that atoms are not indivisible and that in addition to protons, there must also be neutrons present in their nucleus. With Niels Bohr he developed the core-shell model of the atom. 

Scientists initially described radioactivity solely in terms of radiation. The idea of radioactive parf/c/esfirst appeared around the turn of the twentieth century. In 1909, Ernest Rutherford reported confidently that the alpha particle was, in fact, a helium nucleus, jHe, with a 2+ charge. Scientists still had not discovered the proton by this time, so the nature of the helium nucleus (or any other atomic nucleus) was still unknown. In 1919, the existence of the proton was confirmed experimentally by, appropriately enough, Rutherford himself. 

While he was investigating radioactive isotopes with Ernest Rutherford in 1913, George de Hevesy had an idea. Nuclear scientists were commonly forced to work with only tiny quantities of radioactive material, which would be very difficult to see using standard techniques of chemical analysis. But every single atom of a radioisotope advertised its presence when it decayed, since the radiation could be detected with a Geiger counter. So, if a... 

Scientists have known since 1896 that many nuclides are radioactive—that is, they spontaneously emit radiation. Early studies of radioactive nuclei, or radionuclides, by the New Zealand physicist Ernest Rutherford in 1897 showed that there are three common types of radiation with markedly different properties alpha (a), beta (f3), and gamma (y) radiation, named after the first three letters of the Greek alphabet. 

Ernest Rutherford classified this high energy radiation into three major types Alpha particles, Beta particles and Gamma rays. 

While Thomson and others were busy studying electrical phenomena, Henri Becquerel discovered a new phenomenon—radiation. (We will discuss radiation in more detail in Chapter 5.) The study of this new type of high-energy emission from materials was the principal focus of Ernest Rutherford. Rutherford s initial work discovered two new types of particles associated with the high-energy emissions, the alpha (a) particle and the beta ((3). These are now known to be a helium nucleus and an electron, respectively (more on this in Chapter 5). 

Historically, the discovery of radioactivity dates back to 1896 when the French scientist Henri Becquerel believed that the afterglow observed in cathode ray tubes might be associated with phosphorescence, later realizing that this phenomenon was instead due to radiation. At first, this radiation was assumed to be similar to X-rays, but further research by Becquerel and a number of other notable scientists (including Marie Curie and Ernest Rutherford) revealed that the nature of this radiation was more complex. Subsequently, it emerged that there were three principal forms of radioactivity that result from different types of radioactive (nuclear) decay. 

Ernest Rutherford s Work One form of radiation produced by uranium consists of alpha particles. Alpha particles are tiny particles moving at very high rates of speed. In 1907, English physicist Ernest Rutherford (1871-1937) showed that an alpha particle is nothing more than a helium atom without its electrons. As uranium atoms broke apart, then, they... 

Ernest Rutherford was one of the giants in the development of our understanding of atomic structure. While working with J. J. Thomson at Cambridge University, he discovered a and /3 radiation. He spent the years 1899-1907 at McGill University in Canada where he proved the nature of these two radiations, for which he received the Nobel Prize in chemistry in 1908. 

Medieval alchemists spent years trying to convert other metals into gold without success. Years of failure and the acceptance of Dalton s atomic theory early in the nineteenth century convinced scientists that one element could not be converted into another. Then, in 1896 Henri Becquerel discovered radioactive rays (natural radioactivity) coming from a uranium compound. Ernest Rutherford s study of these rays showed that atoms of one element may indeed be converted into atoms of other elements by spontaneous nuclear disintegrations. Many years later it was shown that nuclear reactions initiated by bombardment of nuclei with accelerated subatomic particles or other nuclei can also transform one element into another—accompanied by the release of radiation (induced radioactivity). 

Near the turn of the 20" century, French scientists discovered radioactivity, the emission of particles and/or radiation from atoms of certain elements. Just a few years later, in 1910, the New Zealand-born physicist Ernest Rutherford (1871-1937) used one type of radioactive particle in a series of experiments that solved this dilemma of atomic structure. 

In 1898, in Cambridge, England, a New Zealander, Ernest Rutherford, demonstrated that there were at least two different types of radiation with different penetrating power. He called these alpha and beta radiation. He subsequentiy worked at McGill University in Montreal, Canada, and found more radioactive elements different types of radium and thorium, and actinium. He proposed that these were links in chains of radioactive materials, called the transformation theory. Rutherford and his colleague, Frederic Soddy, described that the rate of decay of radioactive elements were characteristic of the element, and came to be known as half-life. Decay follows the law of probability. Over a given period of time, each atom has a certain probability of decaying, a process that results from the random movements of the subatomic components of the radioactive atoms. This was the first instance in physics of a truly unpredictable phenomenon. The decay of a radioactive atom was probabilistic. 

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