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Historical development of atomic theory
Historical development of atomic theory
Development of atomic theory and contributors
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The Atomic Theory is a theory that explains what matter is made of. The Atomic theory states that matter can’t be divided as it is made up of minute particles called atoms that cannot be separated. The very word atom is derived from the Greek word Atmos which means indivisible.
Atomic theory timeline-
Year Person/People Event
442 BCE Democritrus and Leucippus These Greek philosophers came up with the idea that all matter is composed of indivisible elements.
1803 John Dalton British chemist and physicist John Dalton theorised that matter is composed of spherical atoms (that are in motion) of different weights and are combined in ratios by weight.
1896 Wilhelm Rontgen Discovered that certain chemicals glowed when exposed to cathode rays. These chemicals were special because they weren’t deflected by the magnetic field produced in the cathode ray tube (which was built by Sir William Crookes in 1870).
He Called these X-rays.
1896 Henri Becquerel Accidentally discovered spontaneous radioactivity.
1898 Pierre and Marie Curie Pierre and Marie hypothesised that radioactive particles cause atoms to break down, then release radiation that forms energy and subatomic particles.
1898 JJ Thomas Discovered the electron, using properties of cathode rays.
1900 Max Planck Introduced the quantum theory- stating that electromagnetic energy could only be released in quantized form.
His ‘quanta’ are now referred to by physicists as ‘photons.’
1905 Albert Einstein Created special and general theories of relativity and speculated upon the particle nature of light. This was the basis of understanding nuclear energy.
1908 Robert Millikan Measured the charge of an electron. The charge of one electron is known as the elementary charge.
1909 -- Ernest ...
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...ces are secondary sources, I had to be very careful that the websites that I chose contained reliable information and diagrams. I believe that I have been very careful with my sources and have chosen ones that are both accurate and informative and have helped me to develop my ideas about Marie Curie and the atomic theory in many ways.
Works Cited
http://www.softschools.com/timelines/atomic_theory_timeline/95/ http://www.nobelprize.org/nobel_prizes/themes/physics/curie/ http://www.buzzle.com/articles/accomplishments-of-marie-curie.html http://www.aip.org/history/exhibits/curie/resbr2.htm http://www.earthmagazine.org/article/benchmarks-henri-becquerel-discovers-radioactivity-february-26-1896 http://www.aps.org/publications/apsnews/200412/history.cfm http://www.nist.gov/pml/general/curie/1927.cfm
http://www.aip.org/history/curie/brief/03_radium/radium_2.html
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As a scientist, Millikan made numerous momentous discoveries, chiefly in the fields of electricity, optics, and molecular physics. His earliest major success was the accurate determination of the charge carried by an electron, using the elegant "falling-drop method"; he also proved that this quantity was a constant for all electrons (1910), thus demonstrating the atomic structure of electricity. Next, he verified experimentally Einstein's all-important photoelectric equation, and made the first direct photoelectric determination of Planck's constant h (1912-1915). In addition his studies of the Brownian movements in gases put an end to all opposition to the atomic and kinetic theories of matter.
Niels Bohr was a major contributor to modern physics. He won a Nobel Prize for his work on the atomic model. Also he came up with a way to furthermore define what a nucleus looks like, and also worked on the Quantum theory. He accomplished all of this while living in Copenhagen, Denmark and being a Jewish Chemist during World War II. Post-war he became a major contributor to his Open-World theory of helping Nations intelligence between each other about weapons of mass destruction.
An atom, by definition, is the smallest part of any substance. The atom has three main components that make it up: protons, neutrons, and electrons. Protons and neutrons are within the nucleus in the center of the atom. The electrons revolve around the nucleus in many orbitals. These orbitals consist of many different shapes, including circular, spiral, and many others.
Thus, Einstein was one of the fathers of the nuclear age. Einstein's famous equation, E equals m times c-squared (energy equals mass times the velocity of light squared), became a foundation stone in the development of nuclear energy. Einstein developed his theory through deep philosophical thought and through complex mathematical reasoning. The great scientist was once reported to have said that only a dozen people in the world could understand his theory. However, Einstein always denied this report. See Relativity.
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Her hypothesis was this: The emission of rays from Uranium compounds could be an atomic property of the element Uranium-something built into the very structure of the atoms. During Marie's time, the atom was thought to be the smallest particle in existence.... ... middle of paper ... ...
The inevitable discovery of atomic power started back in 1898. According to Fetter-Vorm, “The chemist Marie Curie and her husband, Pierre, discovered the elements polonium and radium, which both emitted a mysterious energy. They called this energy radioactivity”(4). By 1911 a British physicist discovered
The theory of quantum mechanics has divided the atom into a number of fundamental sub-atomic particles. Although the physicist has shown that the atom is not a solid indivisible object, he has not been able to find a particle which does possess those qualities. Talk of particles, though, is misleading because the word suggests a material object. This is not the intention for the use of the word in quantum physics. Quantum particles are, instead, representations of the actions and reactions of forces at the sub-atomic level. In fact, physicists are less concerned with the search for a material particle underlying all physical objects and more interested in explaining how nature works. Quantum theory is the means that enables the physicist to express those explanations in a scientific way.
This experiment was first done by J.J Thomson in 1897. The result from this was that he discovered that the atom was not a fundamental unit of matter and that it had charged constituents that could not be separated. Thomson investigated the nature of the cathode rays which then resulted in the conclusion that the cathode rays were negatively charged constituents of the atom; hence the discovery of the electron.
Scientists from earlier times helped influence the discoveries that lead to the development of atomic energy. In the late 1800’s, Dalton created the Atomic Theory which explains atoms, elements and compounds (Henderson 1). This was important to the study of and understanding of atoms to future scientists. The Atomic Theory was a list of scientific laws regarding atoms and their potential abilities. Roentagen, used Dalton’s findings and discovered x-rays which could pass through solid objects (Henderson 1). Although he did not discover radiation from the x-rays, he did help lay the foundations for electromagnetic waves. Shortly after Roentagen’s findings, J.J. Thompson discovered the electron which was responsible for defining the atom’s characteristics (Henderson 2). The electron helped scientists uncover why an atom responds to reactions the way it does and how it received its “personality”. Dalton’s, Roentagen’s and Thompson’s findings helped guide other scientists to discovering the uses of atomic energy and reactions. Such applications were discovered in the early 1900’s by using Einstein’s equation, which stated that if a chain reaction occurred, cheap, reliable energy could b...
Democritus was the leader of a group called Atomists. Although they were unable to prove that matter was made up of small particles, they were the first to come up with the idea. Democritus believed that atoms differed in size, shape, and movement but were all made of the same substances. Aristotle was the most important scientific philosopher in Greece. He believed that all matter on earth consisted of four pure substances or elements, which were earth, air, fire, and water. He also believed that the earth was the centre of the universe, and that anything beyond the earth consisted of a fifth pure substance called quintessence. Archimedes was an inventor and mathematician, who discovered several basic scientific principles and developed a number of measuring techniques. Ptolemy was an Egyptian astronomer. He developed a model for predicting the positions of the sun, moon, stars, and planets. Like Aristotle, he believed that the earth was the center of the universe. Between 400 AD. and 1000 AD.
Michael Faraday is a British physicist and chemist, best known for his discoveries of electromagnetic induction and of the laws of electrolysis. He was born in 1791 to a poor family in London, Michael Faraday was extremely curious, questioning everything. He felt an urgent need to know more. At age 13, he became an errand boy for a bookbinding shop in London. He read every book that he bound, and decided that one day he would write a book of his own. He became interested in the concept of energy, specifically force. Because of his early reading and experiments with the idea of force, he was able to make important discoveries in electricity later in life. He eventually became a chemist and physicist.