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Aristotle believed that all matter was made of five main things; earth, air, fire, water, and Aether. Aether was what made up the galaxy, stars, and outer space. Aristotle was very personable and his theory was widely accepted for thousands of years.
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Proposed atomic theory:
*Everything is made of atoms
*Atoms of same element are the same and atoms of different atoms are different
*All atoms had different shapes which determined the element's characteristics
*Atoms could combine with other atoms -
Alchemists coined the term element and analyzed matter with special equipment as well as improved techniques of distillation/crystallization.
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Did extensive studies and experiments on static electricity. Made discoveries about electricity by observing lightning.
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He was the pioneer of bioelectromagnetics. He studied how electrical currents and electrons were used in the body, specifically in the nervous system. Conducted an experiment and found that a dead frog's leg would move when struck with electrons.
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Came up with the law of conservation of mass. Determined that the mass of the rectants and products would be equal in any chemical reaction.
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First scientist to state the theory of constant composition. Discovered that all chemical compounds will have the same composition of elements.
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He was the inventor of the first electrical battery and the discoverer of methane. His invention allowed scientists to produce steady flows of electric current for the first time.
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Proposed his atomic theory which has been modified slightly for use in present day.
*All matter is made of atoms
*All atoms of the same element have the same size and mass
*Atoms cannot be created, divided, or destroyed
*Atoms of different elements combine in whole number proportions
*In chemical reactions, atoms are rearranged -
Avogadro hypothesized that if the pressure and temperatures were the same, then equal volumes of gases would contain equal numbers of molecules. Also hypothesized that simple gases were not formed out of solitary atoms but were compound molecules.
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Used electrolysis to split molecules with electricity. He was the first person to associate electricity and atoms.
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Arranged elements by properties and developed the periodic law. Discovered that elements "were periodic functions of the their atomic weights".
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Crookes experimented with sending an electric current through a tube with electrodes at either end. The particles could penetrate though sheets of metal which led him to conclude that electrons were smaller than atoms and molecules.
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First person to make and detect EMR in the wavelength of X-rays. Invented the X-ray generator.
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Discovered radiocativity through the use of unexposed photo film and uranium. He discovered that uranium naturally emitted radioactive rays without having to sit in the sun at all which led to his conclusion that the uranium was emitting X-rays.
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Used experiments to determine the chage to mass ratio of an electron. Also developed the plum pudding model of an atom.
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Studied the elements uranium and thorium extensively because they were interested in their spontaneous decay which they named radioactivity. They also discovered the elements polonium and radium.
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Contributed information about the chemistry of radioactive atoms and also investigated the origin and nature of isotopes.
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Developed the equation E=mc2 Determined that the speed of light was always constant and that mass and kinetic energy were equal.
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Invented the Geiger counter to measure radiation. He was the first person to create a device that successfully measured individual alpha particles.
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Planck was able to determine the relationship between energy and the frequence of radiation. Used quantum theory and published two books about thermodynamics.
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Millikan performed the oil drop experiment where the oil droplet had a small charge and Millikan would measure how strong the electric field had to be to stop the drop from reaching the bottom. From this information, he determined the change of the electron.
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Coined the terms alpha and beta radiation. Found that radiation was emitted from uranium and thorium and directed the gold foil experiment.
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Bohr modified Rutherford's model because he believed that the electrons would travel in a fixed circle around the nucleus. Bohr also believed that the electrons could jump between orbitals.
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Suggested that electrons, like light, could travel in both particles and waves. His ideas explained the restricted orbitals that the electrons were known to travel in.
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Used mathematics to describe the movement of electrons in their orbitals. He also used quantum mechanics to contribute to the atomic theory.
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Concluded that electrons are in continuous clouds. He used wave mechanics as a mathematical model of he atom.
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Theoretical physicist who contributed to the developing quantum mechanics and quantum electrodynamics. Derived important mathematical equations that helped explain the atom.
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Conducted an experiment where he shot alpha particles at beryllium atoms and found that a beam was given off when this occured. He tested the beam with a magnet and found that it did not have a charge; this beam was made of neutrons.
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Lead a team of scientists who discovered nuclear fission of uranium when they performed an experiment and it absorbed an extra neutron.
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He synthesized, discovered, and investigated ten transuranium elements.
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Created the world's first nuclear reactor using gathered information about fission and fusion.
