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Jan 1, 1000
Aristotle - 322 BC - all matter being made of the four elements: fire, water, earth, and air.
384 BC – 322 BC
Aristotle’s theory made a great generalization off all matter being made of the four elements: fire, water, earth, and air. He also believed that there were four qualities to these elements: dryness, hotness, coldness, and moistness. Based on these beliefs fire would hold the characteristics of being dry and hot, water is wet and cold, air is hot and wet, while the earth is dry and cold. As strange as this theory may seem now, it was used for nearly two thousand years before the -
Jan 1, 1005
Democritus - commonly recognized as the greatest upholder of Atomistic theory in the ancient world 370 BC
Democritus, born around 460 B.C.-370 B.C, in the small Greek city-state Abdera, is commonly recognized as the greatest upholder of Atomistic theory in the ancient world. Although these theories were prehistoric and incorrect, they were involved in the creation of modern atomic theory and the discovery of the atom. Democritus believed that all matter was composed of atoms, and each atom was separated by an amount of space. Democritus described atoms as solid, having no clear internal structure an -
Antoine Lavoiser - developed the Law of Conservation of Mass in 1789
"History of the Atom." Angelfire. N.p., n.d. Web. 13 Apr. 2013. http://www.angelfire.com/alt2/atom/sci2.html#24.
Antoine Lavosier (26 August 1743 – 8 May 1794) is known as the father of Modern Chemistry. Although many of his scientific breakthroughs proved to be crucially important in the discovery of the atom, Lavosier himself believed that the existence of atoms was scientifically impossible. He developed the Law of Conservation of Mass in 1789. This law described elements as pure substances -
John Dalton - that chemical reactions can be explained by the union and separation of atoms
Dalton, (6 September 1766-27 July 1844) was studying Meteorology when discovering his theory. On January 1, 1803, his theory was that evaporated water exists in the air as an individual gas. He performed many experiments regarding this theory. Some details of Dalton’s theory are known to be incorrect, but a core concept of his theory (that chemical reactions can be explained by the union and separation of atoms, and that these atoms have characteristic properties) is a principle of science today -
Henri Becqueral - In 1896, his previous work was overshadowed by his discovery of the phenomenon of natural radioactivity
"History of the Atom." Angelfire. N.p., n.d. Web. 13 Apr. 2013. http://www.angelfire.com/alt2/atom/sci2.html#24.
Henri Becquerel was born in France in the year 1852. Henri Becquerel had discovered radioactivity, later defined as the unplanned discharge of radiation by a certain material due to decomposition. For his discovery, which increased the understanding of X-rays almost immeasurably and opened up new possibilities for radioactive studies, Becquerel was awarded the Nobel Prize for Physi -
J. J. Thomson - whose accomplishments did more to shape the human understanding of the atom than anyone in history.
J. J. Thomson, an unassuming, mild-mannered English physicist, can possibly be described as a man whose accomplishments did more to shape the human understanding of the atom than any other in history. It was Thomson’s discoveries that finally shattered the preordained concept of the heavy, solid, absolutely indivisible atom and replaced it with the concept that the atom was in fact itself comprised of smaller particles, a concept that we still study to this day. We know them today as electrons. -
Max Planck - Planck had focused on the gaps that were still present in the understanding of the radioactive processes
"History of the Atom." Angelfire. N.p., n.d. Web. 13 Apr. 2013. http://www.angelfire.com/alt2/atom/sci2.html#24.
Max Planck was born in Kiel, Germany in 1858, the son of a prosperous law professor. By 1898, Planck had focused on the gaps that were still present in the understanding of the radioactive processes, particularly in the distribution of energy during such radioactive processes. In a series of papers published in 1900, Planck revealed that he had successfully uncovered the relationshi -
Marie Sklodowska & Pierre Curie - Define and create the term "Radioactivity"
"History of the Atom." Angelfire. N.p., n.d. Web. 13 Apr. 2013. http://www.angelfire.com/alt2/atom/sci2.html#24.
Maria Sklodowska, a mathematician and scientist born in Poland in 1867, along with her husband Pierre Curie, a French professor of physics, represent two of the greatest and best known scientific minds of the early 20th century. The Curies were the first to actually create the term “radioactivity,” and were the first to identify, isolate, and study the properties of two important ra -
Millikan used his famous oil-drop experiment
Robert A. Millikan was born in Illinois in 1868. Millikan became determined to follow a singular line of research; the discovery of the basic unit of the electric charge. In order to simplify this, Millikan used his famous oil-drop experiment, which was actually inspired by other similar experiments, which had been conducted earlier, although none had been nearly as successful as Millikan’s would prove to be.
Other scientists had tried to observe the effect of electric fields on large quantitie -
Ernest Rutherford - He discovered not only the positive charged particle that we know of as the proton, but also the fact that the atom actually possesses a nucleus
Ernest Rutherford, born August 30 1871-October 19 1937, in New Zealand, became known as the father of nuclear physics. He discovered not only the positive charged particle that we know of as the proton, but also the fact that the atom actually possesses a nucleus, a discovery practically overpowered previous concepts of the atoms, which had viewed the atom as solid and possessing no internal structures. We still use this today. He discovered this on 31st of October 1909 -
Moseley’s use of X-rays
. Moseley’s breakthroughs involved the use of X-rays; he used cathode rays to bombard elemental samples, and was then able to photograph the X-rays that resulted. This allowed Moseley to postulate that an atom could be identified by the charge on its nucleus; by observing that the paths of certain lines in the x-ray spectrum moved when the atomic number was increased, Moseley also discovered that the atomic number can be used to supply the number of protons within the nucleus of an atom. Moseley -
Niels Bohr - He also suggested that the outer orbits, including what we now know of as the “valance shell,” could hold more electrons than inner orbits, and thus determined many of the atom’s properties.
Bohr put detail upon this; he suggested that the electrons could travel only in consecutively expanding orbits. Bohr also discovered that the outer shells could hold more electrons than the inner ones. During World War II, Bohr helped scientists such as Enrico Fermi and J. Robert Oppenheimer, who were heavily involved with the secretive Manhattan Project. He died in his hometown of Copenhagen in 1962. This was discovered on the 15th of May 1913. -
Erwin Schrodinger - published works proposing that wave mechanics was the actual mathematical model of the atom
"History of the Atom." Angelfire. N.p., n.d. Web. 13 Apr. 2013. http://www.angelfire.com/alt2/atom/sci2.html#24.
Erwin Schrodinger (1887-1961) Vienna, Austra. All of Schrodinger’s research efforts came to a close in 1930, when he finally published works proposing that wave mechanics was the actual mathematical model of the atom; these works were heavily influenced by the work of Heisenberg and Einstein, and also dealt with the theory of relativity. -
James Chadwick - He shortly afterward joined the Manhattan Project in the United States that developed the two atomic bombs that were dropped on the Japanese Empire
20 October 1891 – 24 July 1974 in Bollington, Cheshire. On September 28, 1932, Chadwick discovered a previously unknown particle in the atomic nucleus. For Chadwick's discovery of the neutron, Chadwick’s discovery of the neutron made it possible to produce elements heavier than uranium in the laboratory, by the capture of slow neutrons followed by beta decay. He shortly afterward joined the Manhattan Project in the United States that developed the two atomic bombs that were dropped on the Japan -
Werner Heisenberg - include the foundation of quantum mechanics.
Werner Heisenberg
Werner Heisenberg was born in December, 1901, in Bavaria, which at the time was a German state. He showed an interest in the sciences from a young age, and entered into the University of Munich in 1920; while at Munich, he pursued a doctorate in physics, but soon found that he had almost no interest in experimental physics. Rather, Heisenberg’s interests lay primarily in theoretical physics, which he would study for
