when was the atom discovered?
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The ancient Greeks thought of the idea of the atom - 5th century B.C. (about 2600 years ago), but they did not have the tools to test their theories this far back in time.\n\nBy the 19th century (the 1800's) technology had advanced greatly and many elements (group of similar atoms) had been discovered. Using the available elements scientist such as John Dalton and Amedeo Avogadro forced them to interact with one another. From these interactions they were able to prove the existence of the atom.\n\nTowards the end of the 19th century J.J. Thomson discovered that the atom was made up of smaller particles. Through experiments with the gas neon, Thomson discovered a negatively charged particle with a mass much smaller than the atom. This particle is known as the electron and is one of the constituent particles of the atom.\n\nAtoms are typically neutral (they do not have a charge). So when the electron (a negative particle) was discovered, scientist reasoned that there must be a positive charge somewhere in the atom to offset the negative charge. Electrons are also very light compared to the mass of an atom. Therefore, the missing positive particle had to be heavy to account for the missing mass of the atom.\n\nIn 1911 the scientist Ernest Rutherford found the missing particle.
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Discovery of the 10th planet!  Recent discovery.  Not much info. yet so no one can say if you are wrong on any point!
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The use of uranium, in its natural oxide form, dates back to at least AD 79, when it was used to add a yellow colour to ceramic glazes (yellow glass with 1% uranium oxide was found near Naples, Italy). When this was rediscovered, in the earlier part of the 19th century, the world’s only known source of uranium 'earths' were the old Hapsburg silver mines in Joachimsthal, Bohemia, and the local glassmaking industry kept a tight lid on the secret ingredient and its supply as long as it could.\n\nThe discovery of the element is credited to the German chemist Martin Heinrich Klaproth who in 1789 found uranium in a mineral called pitchblende. It was named after Uranus the planet , which had been discovered eight years earlier by William Herschel. It was first isolated as a metal in 1841 by Eugene-Melchior Peligot. In 1850 the first commercial use of Uranium in glass was developed by Lloyd & Summerfield of Birmingham, England. Uranium was found to be radioactive by French physicist Henri Becquerel in 1896, who first discovered the process of radioactivity with uranium minerals.
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His parents ...\n\nIf you are asking what Einstein discovered, Einstein's contributions to physics began in 1905 with three major results: the explanation of Brownian motion in terms of molecules; the explanation of the photoelectric effect in terms of the quantum; and the special theory of relativity that links time to space and energy to matter. From 1907 to 1915 Einstein developed general relativity, a theory of gravity more accurate than Newton's; it became the basis of theoretical cosmology. In failed efforts in the 1930s to refute the interpretation of quantum theory in terms of probability, Einstein contributed to the theoretical basis for what is sometimes called teleportation of photons (which Einstein called "spooky action at a distance"). His last major effort was an attempt to unify electromagnetism and gravity into a single unified field theory, still an active problem of physics.
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The atomic number is the number of protons.
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Pluto was discovered by the astronomer Clyde Tombaugh at the Lowell Observatory in Arizona on February 18, 1930 after an extensive search when he compared photographic plates taken on January 23 and 29. After the observatory obtained confirming photographs, the news of the discovery was telegraphed to the Harvard College Observatory on March 13, 1930. The planet was later found on photographs dating back to March 19, 1915. Tombaugh was searching for a "Planet X" to explain discrepancies in the predicted orbit of Neptune. It is now known these discrepancies were an artifact of the slightly incorrect value then assumed for the mass of Neptune.
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Probably gold was one of the first elements "discovered". However, copper as well has been known since prehistoric times. Iron has been known since prehistoric times, as has zinc, silver, tin, lead and mercury. Where these were discovered first, and by who, is not clear. However, there are clearly a lot of contenders for the "first element", if one wants to choose among these. \n\nIf one looks for more modern discoveries, then these are better documented (look at the attached reference). Some early contenders are listed below:\n\nCobalt was discovered by Swedish Chemist Georg Brandt in 1735. \n\nCavendish found hydrogen in 1766.  \n\nJoseph Black of Scotland found magnesium was a separate element in 1755. \n\nNickel was found by Swedish metallurgist Axel-Frederik Cronstedt in 1751. \n\nDaniel Rutherford discovered nitrogen in 1772. \n\nCarl-Wilhelm Scheele in 1771 discovered oxygen is an element in Sweden. \n\nGerman merchant and alchemist Hennig Brand found phosphorus in 1669.\n\nOf the modern elements,  phosphorus appears to be the first found, in Germany.
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Chlorine (Gr. χλωρος, greenish yellow) was discovered in 1774 by Swedish chemist Carl Wilhelm Scheele, who mistakenly thought it contained oxygen. Chlorine was given its name in 1810 by Sir Humphry Davy, who insisted that it was in fact an element.\n\nChlorine gas was first used as a weapon against human beings in WWI on April 22nd, 1915.
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Nucleic acids were discovered in 1869 by Johann Friedrich Miescher (1844-1895), who called the material 'nuclein' since it was found in the nucleus. It was later discovered that prokaryotic cells, which do not have a nucleus, also contain nucleic acids
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Not sure you can get an exact ranking, because three were researched simultaneously:\n\nHelium was discovered on Earth in 1895 by Scottish chemist Sir William Ramsay, though some credit the discovery of helium (in the sun's spectrum) to Janssen and Lockyear in 1868. Ramsay discovered most of the remaining noble gases--argon in 1894 (with Lord Rayleigh) and krypton, neon, and xenon in 1898 (with Morris M. Travers). Radon was discovered in 1898 by Fredrich Ernst Dorn.
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A molecule is made up of atoms.
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He discovered that atoms are not indivisible and are actually made up of smaller particles, electrons. When he first discovered electrons, he formed three hypotheses:\n\n1. Cathode rays are charged particles (which he called "corpuscles"). \n2. These corpuscles are constituents of the atom. \n3. These corpuscles are the only constituents of the atom. \n\nThere were minor changes made to his first and second hypotheses, but the third was completely wrong.\n\nNOTE: The table of contents to the first link is on the bottom left of the page.
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Gamma rays were discovered by the French chemist and physicist, Paul Ulrich Villard in 1900 while he was studying uranium. Working in the chemistry department of the École Normale in rue d'Ulm, Paris with self-constructed equipment, he found that the rays were not bent by a magnetic field.
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electrons were discovered by  william crooks by discharge tube experiment and named it electron by stoney and cathode rays by julius plucker .protons were discovered by  goldstein\n again by discharge experiment by placing the perforated cathode in the middle of discharge tube.\nproperties of electron:-\n1. made up of material particles\n2. carrying negative charge\n3. affect photographic plate\n4. follow the straight path\n5. e/m ratio is constant\nproperties of protons:-\n1.carry positive charge\n2. specific charge(9.58*10000c/gm)\n3. proton upon mass ratio is not constant
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This is a homework question & better not be one of my students! LOL\n\nThe answer is atom.\n\nClassic textbook question. For those of you who thought the question was confusing, take it up w/ the authors of high school textbooks. I will gladly back you up on it. LOL\n\n:)
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The nucleolus suborganelle was originally discovered in eels by the Italian scientist Felice Fontana in 1774. He was able to see the large, darkly stained nucleolus under a simple light microscope. However, its function wasn't discovered until two centuries later.
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Thallium (Greek θαλλός, thallos, meaning "a green shoot or twig") was discovered by Sir William Crookes in 1861 in England while he was making spectroscopic determinations for tellurium on residues from a sulfuric acid plant. The name comes from Thallium's bright green spectral emission lines. In 1862 Crookes and Claude-Auguste Lamy isolated the metal independently of each other.