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Joseph John Thomson
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Joseph John "J.J." Thomson, (Mánchester, Inglaterra, 18 de diciembre de 1856 - Cambridge, Inglaterra, 30 de agosto de 1940) fue un científico británico, descubridor del electrón, de los isótopos e inventor del espectrómetro de masa. En 1906 fue galardonado con el Premio Nobel de Física.
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Trabajos sobre los rayos catódicos Tercer experimento En su tercer experimento (1897), Thomson determinó la relación entre la carga y la masa de los rayos catódicos, al medir cuánto se desvían por un campo magnético y la cantidad de energía que llevan. Encontró que la relación carga/masa era más de un millar de veces superior a la del ion Hidrógeno, lo que sugiere que las partículas son muy livianas o muy cargadas. Las conclusiones de Thomson fueron audaces: los rayos catódicos estaban hechos de partículas que llamó "corpúsculos", y estos corpúsculos procedían de dentro de los átomos de los electrodos, lo que significa que los átomos son, de hecho, divisibles. Thomson imaginó que el átomo se compone de estos corpúsculos en un mar lleno de carga positiva; a este modelo del átomo, atribuido a Thomson, se le llamó el modelo de pudín de pasas. En 1906 fue galardonado con el Premio Nobel de Física por su trabajo sobre la conducción de la electricidad a través de los gases. La imposibilidad de explicar que el átomo está formado por un núcleo compacto y una parte exterior denominada corteza implica que otros científicos como Ernest Rutherford o Niels Bohr continuasen con su investigación y establecieron otras teorías en las que los átomos tenían partes diferenciadas.
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Synopsis J.J. Thomson was born on December 18, 1856, in Cheetham Hill, England, and went on to attend Trinity College at Cambridge, where he would come to head the Cavendish Laboratory. His research in cathode rays led to the discovery of the electron, and he pursued further innovations in atomic structure exploration. Thomson won the 1906 Nobel Prize in Physics, among many accolades. He died on August 30, 1940.
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Early Life and Education Joseph John Thomson, who was always called J.J., was born in Cheetham Hill, England, near Manchester, in 1856. His father was a bookseller who planned for Thomson to be an engineer. When an apprenticeship at an engineering firm couldn't be found, Thomson was sent to bide his time at Owens College at the age of 14. In 1876, he received a small scholarship to attend Trinity College at Cambridge to study mathematics. Thomson worked in the Cavendish Laboratory after graduation, under the tutelage of Lord Rayleigh. He quickly earned a membership in the prestigious Royal Society and was appointed Rayleigh’s successor as the Cavendish Professor of Physics at the age of 28. He was both respected and well-liked, and students came from around the world to study with him.
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Antecedentes They were first observed in 1869 by German physicist Johann Wilhelm Hittorf, and were named in 1876 by Eugen Goldstein Kathodenstrahlen, or cathode rays. [1][2] In 1897, British physicist J. J. Thomson showed that cathode rays were composed of a previously unknown negatively charged particle, which was later named the electron. Cathode ray tubes (CRTs) use a focused beam of electrons deflected by electric or magnetic fields to create the image on a television screen.Johann Wilhelm HittorfEugen Goldstein [1][2]J. J. ThomsonCathode ray tubes
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J.J. Thomson's experiment and the charge-to-mass ratio of the electron The first is the experiment of Joseph John Thomson, who first demonstrated that atoms are actually composed of aggregates of charged particles. Prior to his work, it was believed that atoms were the fundamental building blocks of matter. The first evidence contrary to this notion came when people began studying the properties of atoms in large electric fields. If a gas sample is introduced into the region between two charged plates, a current flow can be observed, suggesting that the atoms have been broken down into charged constituents. The source of these charged particles is a heated cathode that, in fact, causes the atoms of the sample to ionize. These were known as cathode rays. In 1897, Thomson set out to prove that the cathode rays produced from the cathode were actually a stream of negatively charged particles called electrons. (See Figure 1.8 in the textbook for Thomson's experimental setup). From Maxwell's theory, he knew that charged particles could be deflected in a magnetic field. A schematic of the experimental setup is shown below:
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Research In 1894, Thomson began studying cathode rays, which are glowing beams of light that follow an electrical discharge in a high-vacuum tube. It was a popular research topic among physicists at the time because the nature of cathode rays was unclear. Thomson devised better equipment and methods than had been used before. When he passed the rays through the vacuum, he was able to measure the angle at which they were deflected and calculate the ratio of the electrical charge to the mass of the particles. He discovered that the ratio was the same regardless of what type of gas was used, which led him to conclude that the particles that made up the gases were universal. Thomson determined that all matter is made up of tiny particles that are much smaller than atoms. He originally called these particles 'corpuscles,' although they are now called electrons. This discovery upended the prevailing theory that the atom was the smallest fundamental unit. In 1906, Thomson began studying positively charged ions, or positive rays. This led to one of his other famous discoveries in 1912, when he channeled a stream of ionized neon through a magnetic and an electric field and used deflection techniques to measure the charge to mass ratio. In doing so, he discovered that neon was composed of two different kinds of atoms, and proved the existence of isotopes in a stable element. This was the first use of mass spectrometry.
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