DEVELOPMENT OF THE ATOMIC THEORY Part A: HISTORY * 1869: Mendeleev formulated the Table of the Elements - listing them by their atomic weight and grouping them with similar characteristics. * 1897: JJ Thomson discovered electron and isotopes‚ and invented the mass spectrometer. * 1898: Marie Curie discovered and isolated radium‚ a new element which unprompted disintegrated into other elements. This proved that the atoms of one element at least were not indivisible. * 1911: Ernest
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proton and an electron? (1) They have the same masses and the same charges. (2) They have the same masses and different charges. (3) They have different masses and the same charges. (4) They have different masses and different charges. 3 The atomic mass of an element is the weighted average of the masses of (1) its two most abundant isotopes (3) all of its naturally occurring isotopes (2) its two least abundant isotopes (4) all of its radioactive isotopes 4 Which statement is true about
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6th 1945 the United States dropped an atomic bomb on Hiroshima‚ Japan. Three days later‚ they dropped a second one on another Japanese city‚ Nagasaki. Those two bombs were first and only atomic weapons ever used in actual combat. Until atomic bombs were reported in “The New York Times”‚ most American citizens had never heard of atomic bombs. Ordinary bombs had been an important part of World War II‚ and they brought much destruction to both sides. This atomic bomb‚ the equivalent of 20‚000 tons of
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Effects of the Atomic Bomb Ryan McNall Southern Vermont College In our vast history of events‚ we have learned a lot about radiation. One event in time that had a big effect on what we know about radiation was when the first atomic bomb was dropped on Hiroshima‚ Japan in 1945. This attack started the nuclear warfare age and gave the world an idea of what radiation can do to your body if it is used in the wrong ways. Before the attack on Japan‚ the United
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1. Atomic and Molecular Structure a. Students know how to relate the position of an element in the periodic table to its atomic number and atomic mass. The Periodic Table organizes elements by their atomic number - from hydrogen (1) to whatever is the highest one currently known (>105). It is arranged so that similiar members fall in a list such as Chlorine Bromine etc.. The average atomic weight is usually shown with each element‚ but due to isotopes (caused buy nuclear varations)
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Atomic Bomb Essay World War II started on September 3 1939‚ When Germany invaded Poland‚ two days later the war started when Britain and France declared war on Germany. But the United States did not get involved until December 7 1941 when Japan bombed a naval base called Pearl Harbor in Hawaii. In 1942 The Manhattan Project started in the United States. The project was to build nuclear weapons. It took three years to construct and test the weapons. The United States had to contact Japan and
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Atomic structure: scientists 1. Democritus: 1st person to think of atom (500 BCE)- philosopher Atom is the smallest piece of an element that has same properties as the element. 2. Lavisier: Law of conservation of mass/ matter • Mass can’t be created or destroy; same amount of stuff 3. Joseph Proust: Law of constant composition (law of definite Proportions) • A compound is always made of the same elements in the same ratio. 4. John Dalton: English school teacher who derived the atomic theory
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The Atomic Model has changed over time‚ as the years‚ decades‚ and centuries go by we get a better understanding of the atom and what it looks like. The Atomic Model has changed drastically based on the understanding we have on it‚ each new model has added more information to what we know about it‚ making it easier for scientists and the world to understand. The Atomic Model is a very important part of Science and Chemistry‚ it helps explain the structure and what is inside the atom‚ the particle
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a physics professor at Columbia University‚ suggests a clock could be made from a technique he developed in the 1930’s called atomic beam magnetic resonance. 1949 Using Rabi’s technique‚ NIST (then the National Bureau of Standards) announces the world’s first atomic clock using the ammonia molecule as the source of vibrations. 1952 NIST announces the first atomic clock using cesium atoms as the vibration source. This clock is named NBS-1. 1954 NBS-1 is moved to NIST’s new laboratories
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August 6‚ 1945‚ the United States shocked the world by dropping an atomic bomb over the city of Hiroshima‚ Japan. (www.grolier.com) Hiroshima was a major industrial city with an estimated population of almost 400‚000 people. A B-29 bomber was loaded with the Atomic Bomb and left the United States Pacific air base at 2:45 a.m. local time and dropped the bomb at 8:15 a.m. The bomb was detonated one minute after being dropped. The atomic bomb‚ nicknamed "Little Boy"‚ which was dropped on the Hiroshima
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