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R. J. John Dalton's Theory Of Atoms

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The Atomic Theory

The atom seems very simple and fundamental to most people but when you look into it further, it can get very complex and the history goes way back to 400 BCE. It all started when a man named John Dalton came up with the first atomic theory. Daltons theory consisted of 5 parts. He believed that all matter is composed of extremely small particles called atoms which cannot be subdivided, created, or destroyed, atoms of a given element are identical in their physical and chemical properties, atoms of different elements differ in their physical and chemical properties, atoms of different elements combine in simple, whole number ratios to form compounds, and in chemical reactions, atoms are combined, separated, or rearranged …show more content…

J.J. Thomson was one scientist who did this. He used a cathode ray to discover the existence of electrons in an atom. With this experiment, he was also able to conclude that electrons are negatively charged because the cathode ray came from a negative charge. Another scientist named Ernest Rutherford discovered the nucleus. He made a model of an atom that he called the plum-pudding model because that is what it resembled. Rutherford also did an experiment that was called the gold foil experiment. This proved that the nucleus of an atom has positive particles in it. He found this out because he directed a thin line of particles at the gold foil and some particles bounced off and were reflected. This also helped him hypothesize that the area outside of the nucleus is not just empty space, it is the electron cloud. Another thing that he was able to hypothesize was that the nucleus nearly makes up all of the mass of an atom. Rutherford was a very influential person to the discoveries of the atom. His gold foil experiment also led to finding protons. Protons are positively charged particles in the nucleus. The other particles that make up the nucleus are neutrons. Neutrons …show more content…

The quantum numbers are basically different orbitals that electrons can be found on. The different orbitals are s,p,d, and f. Each level can only hold a certain amount of of electrons until they move on to the next. The s orbital can hold 2 e-, the p orbital can hold 6 e-, the d orbital can hold 10 e-, and the f orbital can hold 14 e-. A way to find the quantum number of an element is to use the diagonal rule. Each element has different quantum

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Each supernatural, equine Periodic is described differently and no two are described the same way. Each Periodic is different just like each element of the periodic table is unique. Isdell uses physical characteristics of individual elements, such as color, mass and weight, as well as chemical characteristics of individual elements, such as boiling point and melting point, to describe the corresponding Periodic in the book. As Julie journeys through the Elemental Forest, she meets groups of Periodics. Typically these are Periodics that represent groups of elements that are similar but not the same.

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While others thought it was a waste of time he found “As we know today, when a beam of electrons strike an atom, the beam punches out the atom’s own electrons, leaving a hole, Electrons are attached to an atom’s nucleus because electrons and protons have opposite charges, and tearing electrons away from the nucleus is a violent deed” (Kean123). Mosely began to fine tune and hunt for the missing elements, creating the atomic number, determining

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Scientist continued to develop the world's knowledge of the atom. In 1896, Henri Becquerel accidentally discovered radioactivity(Doc.1). Furthermore, in 1911, Ernest Rutherford discovered atoms were made of smaller particles and that they had a positively charged nucleus(Doc.1). Throughout decades, scientist have honed ,developed, and continued in the study of the science of the

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An isotope is two or more different forms to write an element and an isotope has its own form, or symbol that it is written in. J. J Thomson discovered the electron and that they have a negative charge. Since electrons have a negative charge they attract to positive charges, protons. Thomson puts a high voltage to two electrodes sealed inside an evacuated tube, and an invisible ray emanates from the negative cathode. Another important discovery of the electron was done by Robert Millikan.

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In the early 1900’s, Robert Millikan started studying the charge of an atom. He wanted to know whether there was a smallest unit of electric charge and if so, what is this charge and what is its magnitude in Coulombs. In order to test this he took small oil droplets and put them through an atomizer which ionized the oil droplets. He then placed the oil droplets in a closed system between two oppositely charged plates with the negatively charged plate on top. In order to figure out the value of ‘e’ (elementary charge) he had to find the electric force of the fields.

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His vitreous fluid corresponds to what we now call positive charge, and the resinous fluid is now termed negative charge. Charge Carriers More than one hundred years after the work of Benjamin Franklin, the secrets of the atom itself began to be revealed. Moreover, in 1897, J.J. Thomson discovered the electron. Soon after, it was determined that these charged particles existed in all atoms and that a countercharge, carried by some other part of the atom, was necessary to make the overall charge of the atom neutral. In time, the proton was determined to carry this charge.

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The quantum numbers that are used to describe the properties of an electron in an atom are the principal quantum number (n), the angular momentum quantum number (l), the magnetic quantum number (m_l), and the spin quantum number (m_s). According to Pauli's exclusion principle, if two electrons occupy the same energy level in an atom, they must have different values for each of these quantum numbers. Pauli's exclusion principle has important consequences for the behavior of electrons in an atom. It determines the distribution of electrons in an atom and affects the chemical properties of an atom. It also explains the periodic table of the elements, which arranges the elements according to the number of electrons in their atoms.

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There have been many models constructed by scientists who have tried to figured out how an atom is made up and what exactly it is made up of but two of the best atomic models of the atom are Bohr’s atomic model and the Electron cloud model which were both made in the early 1900s . In 1913 the Danish physicist Niels Bohr had created Bohr’s atomic model showing the atom and how it was structured. Bohr’s atomic model was the first known model of an atom that incorporated the quantum theory and also was the predecessor for the wholly quantum- mechanical models that were constructed many years later. Before 1913 it was thought of that an atom had a nucleus with electrons orbiting around it in a circular motion, but this was not the case. It was

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Franklin discovered that an excess of electrical fluid was a positive charge, and a shortage of electrical fluid led to a negative charge. He was also the first to say an electrical charge cannot be created, it can only be collected. In 1751 Franklin published a book called Experiments and Observations on Electricity. This book was widely read in Britain and Europe. ( Benjamin Franklin Bio)

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J.J. Thomson was born December 18 1856 and died August 30 1940. He showed that cathode rays were made of an negatively charged particle and

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In the 1930’s, how was the atom described? In 1932, an english physicist, James Chadwick discovered and confirmed the existence of neutrons, and claimed that neutrons do not have any charge. In an Atomic nuclei, there are the positive charged protons and neutrons. How did having particle accelerators advance

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Rutherford decided that if Thomson was correct with his model, than the atoms mass was widespread through the atom, thus if Rutherford was to shoot high velocity alpha particles (Helium Nuclei) towards an atom, there would be a small amount of substance to deflect the alpha particles. So Rutherford enclosed a radioactive source capable of emitting alpha particles in a protective lead shield. The emitted radiation was focused using a slit in the lead shield. A thin layer of gold sheet was placed in front of the slit, and a zinc coated screen (zinc to render it fluorescent) serving as a counter to detect alpha particles. When each alpha particle hit the fluorescent screen, a burst of light would be produced (called scintillation) only visible through a microscope attached to the back of the screen.

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Fledgling physicist Lise Meitner was interested in radioactivity, and aided by chemist Otto Hahn, she was able to pursue radioactivity, despite being a woman. She discovered that the atom was an example of E = mc^2, and that the unstable nature of the nucleus was simply its mass turning into energy. However, because she was a Jew, she lost everything in the Holocaust. Hahn still carried through with their experiment. When he added neutrons to the uranium nucleus, it did not increase in size; instead, radium began to appear.

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He conduced a gas experiment in which he measured the amount of water vapour that air could absorb at different temperatures and discovered that rather than being a chemical solvent, it was made up of minute, singular particles that are in constant, random motion. He also researched the properties of compounds and found that compounds are combined full of particles that can be different but are not able to be subdivided. This proved that atoms then exist, and proves the theory that scientific conclusions can be justified so long as there is enough evidence to support

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