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Matter could not be divided into smaller and smaller pieces forever, eventually the smallest possible piece would be obtained. This piece would be indivisible. He named the smallest piece of matter “atomos,” meaning “not to be cut.”
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Proposed a mechanical universe with small solid masses in motion.
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it contained a list of elements, or substances that could not be broken down further, which included oxygen, nitrogen, hydrogen, phosphorus, mercury, zinc, and sulfur. His list, however, also included light, and caloric, which he believed to be material substances.
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states that the mass of an isolated system (closed to all transfers of matter and energy) will remain constant over time.
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that elements combine at the atomic level in fixed ratios. This ratio would naturally differ in compounds due to the unique atomic weights of the elements being combined.
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"Experimental Essays" on the constitution of mixed gases; on the pressure of steam and other vapours at different temperatures, both in a vacuum and in air; on evaporation; and on the thermal expansion of gases. These four essays were published in the Memoirs
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Studied the effect of electricity on solutions, coined term "electrolysis" as a splitting of molecules with electricity, developed laws of electrolysis. Faraday himself was not a proponent of atomism.
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Built one of the first gas discharge tubes ("cathode ray tube").
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Arranged elements into 7 groups with similar properties. He discovered that the properties of elements "were periodic functions of the their atomic weights". This became known as the Periodic Law.
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Proposed electric and magnetic fields filled the void.
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Discovered cathode rays had the following properties: travel in straight lines from the cathode; cause glass to fluoresce; impart a negative charge to objects they strike; are deflected by electric fields and magnets to suggest a negative charge; cause pinwheels in their path to spin indicating they have mass.
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Used a CRT to study "canal rays" which had electrical and magnetic properties opposite of an electron.
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Proposed that electricity was made of discrete negative particles he called electrons ".
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Using a CRT he observed that nearby chemicals glowed. Further experiments found very penetrating rays coming from the CRT that were not deflected by a magnetic field. He named them "X-rays"
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While studying the effect of x-rays on photographic film, he discovered some chemicals spontaneously decompose and give off very pentrating rays.
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A cathode ray tube or CRT is a specialized vacuum tube in which images are produced when an electron beam strikes a phosphorescent surface.
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Thomson discovered this through his explorations on the properties of cathode rays. Thomson made his suggestion on 30 April 1897 following his discovery that Lenard rays could travel much further through air than expected for an atom-sized particle.
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Studied radiations emitted from uranium and thorium and named them alpha and beta.
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Studied uranium and thorium and called their spontaneous decay process "radioactivity". She and her husband Pierre also discovered the radioactive elements polonium and radium.
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Observed spontaneous disintegration of radioactive elements into variants he called "isotopes" or totally new elements, discovered "half-life", made initial calculations on energy released during decay.
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used the idea of quanta (discrete units of energy) to explain hot glowing matter.
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Postulated a "Saturnian" model of the atom with flat rings of electrons revolving around a positively charged particle.
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Imagine a plum pudding wherein the pudding itself is positively charged and the plums, dotting the dough, are the negatively charged electrons.
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Discovered that inert gases had a stable electron configuration which lead to their chemical inactivity.
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Published the famous equation E=mc 2
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Developed an electrical device to "click" when hit with alpha particles.
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This experiment involved the firing of radioactive particles through minutely thin metal foils (notably gold) and detecting them using screens coated with zinc sulfide (a scintillator).
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Oil drop experiment determined the charge (e=1.602 x 10 -19 coulomb) and the mass (m = 9.11 x 10 -28 gram) of an electron.
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A source which undergoes alpha decay is placed in a lead box with a small hole in it. Any of the alpha particles which hit the inside of the box are simply stopped by the box. Only those which pass through the opening are allowed to escape, and they follow a straight line to the gold foil.
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Using alpha particles as atomic bullets, probed the atoms in a piece of thin (0.00006 cm) gold foil . He established that the nucleus was: very dense,very small and positively charged. He also assumed that the electrons were located outside the nucleus.
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Using x-ray tubes, determined the charges on the nuclei of most atoms. He wrote"The atomic number of an element is equal to the number of protons in the nucleus". This work was used to reorganize the periodic table based upon atomic number instead of atomic mass.
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In the Bohr Model the neutrons and protons (symbolized by red and blue balls in the adjacent image) occupy a dense central region called the nucleus, and the electrons orbit the nucleus much like planets orbiting the Sun
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Discovered the existence of isotopes through the use of a mass spectrograph.
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The electron cloud model is an atom model wherein electrons are no longer depicted as particles moving around the nucleus in a fixed orbit. Instead, as a quantum mechanically-influenced model, we shouldn’t know exactly where they are, and hence describe their probable location around the nucleus only as an arbitrary
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Discovered the existence of isotopes through the use of a mass spectrograph.
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Electrons are defined as standing waves. The electron probability distribution gives the areas in which the probability of electron presence is high. The exact position of the electron is never known as stated by the Heisenberg uncertainty principle:
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Discovered that electrons had a dual nature-similar to both particles and waves. Particle/wave duality. Supported Einstein.
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Described atoms by means of formula connected to the frequencies of spectral lines. Proposed Principle of Indeterminancy - you can not know both the position and velocity of a particle.
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Built an early linear accelerator and bombarded lithium with protons to produce alpha particles
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Viewed electrons as continuous clouds and introduced "wave mechanics" as a mathematical model of the atom.
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Using alpha particles discovered a neutral atomic particle with a mass close to a proton. Thus was discovered the neutron.
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He was known for being a reliable philosopher. As a result, his ideas had a much greater impact on people. His ideas when it came to matter, however, were slightly different than his predecessor, Democritus. Aristotle believed all things were made of: matter and essence. Aristotle thought organisms of the same species were made of the same but different matter. Aristotle believed matter could be broken down into the four elements. His beliefs were accepted over democritus's.
