원자론

박영동교수 원자설과그파급 Unobtainium - $20 million per kg 그리스철학과원자론 다양한세계를단일한원리로환원하는작업오감이포착한 보이는 세계의다양성과유동성을좀더확실하고변하지않는소수의원리를토대로해서설명 그러나원자론의제창자로알려진데모크리토스에대해비판적인태도를취했으며원자론을대신해서사성질설의입장을견지했던아리스토텔레스또한공유하고있던출발점 레우키포스 : 진공속에서무수한 원자 가운동하고있는데, 이것이모이면 물체 가되고흩어지면 물체 가사라지지만 원자 자체는작아서인간의눈에보이지않는다고생각진공과원자를나누고원자를모든현상의근저로설정 데모크리토스 : 원자들의형태와위치배열, 운동상태가다르기때문에, 이러한상이함이현상적측면에서는 다양성 으로표출된다 Atomos To Democritus, atoms were small, hard particles that were all made of the same material but were different shapes and sizes. Atoms were infinite in number, always moving and capable of joining together. 그리스원자론 오늘날의자연과학은현상을그하위레벨의물질단위와그것을담당하는운동법칙으로설명하려는경향이상당히강함. 예 : 생물학적인현상을아미노산이나단백질을하나의설명단위로설정하고, 이것의이합집산에의해설명이가능하다고생각한다. 화학현상에대해서는원자물리학적원리에따라설명할수있다고생각한다. 이와같은환원주의의원형중하나가레우키포스, 데모크리토스로대표되는그리스원자론이다. 원자론은물질의무한분할을논리적으로허용하지않기때문에, 당연히물질의 연속성 을부정 기계론적물질관 Lucretius (99BC-55BC) On the Nature of Things, (De Rerum Natura) "The universe, in its essential nature is composed of two things, namely matter and the void... All predictable things are either properties or accidents of matter and void "Two kinds of bodies are to be distinguished: there are primary elements of things, and objects compounded of primary elements [atoms]. The ultimate particles are solid and contain no void... They must of necessity be everlasting. Their bodies must consist of unchanging substance..." The atoms, though indivisible, have parts which cannot have an independent existence. In contrast to Heraclitus, fire is not the ultimate substance, nor are there just the four elements championed by Empedocles. etc. 그리스원자론쇠퇴의이유 그리스에서는 모든현상을진공속에존재하는물질입자의운동 으로환원하려한 기계론적 자연관을선호하지않음. 원자론의계보가, 시간이흐르면서점차부정적이미지를갖게된 쾌락주의 의원조에피쿠로스에게연결되고또에피쿠로스의충실한후계자루크레티우스에게이어진다는점 반대견해였던아리스토텔레스의물질관이아리스토텔레스철학체계자체의강력한침투력과더불어사상사의주류가되고, 이것이고대후반기부터융성하기시작한연금술과합치되기때문 원자론의움직임은점차수그러들었고, 비잔틴, 아라비아, 중세라틴세계까지도아리스토텔레스적인목적론적물질관에지배 1

그리스원자론의부활 르네상스시기에들어서면서점차아리스토텔레스의사상구조가흔들리기시작. 루크레티우스의저작인 만물의본성에대하여 등이인문주의자들사이에즐겨읽히면서, 그리스원자론에기반한사고가조금씩서구라틴세계에도침투하기시작. 데카르트 (1596~1650) 의좋은논적인가상디 (1592~1655) 에의해, 그리스원자론은유럽에서전면적으로부활 보일은디오게네스 ( 디오게네스라에르티오스, AD 3 세기 ) 의저명한저작 철학자열전 에서에피쿠로스부분을읽고처음으로원자론적발상을접했다고함. 보일은데카르트의 기계론 과갈릴레이 (1564~1642) 의 신과학 에강한매력을느꼈고, 연금술분야를새로운지식체계의중요한한분야로위치시키고자했음. 16C 와 17C 에일어난변화 16C 와 17C 사이에인간의세계관과사고방식에극적인변화 15C 이전유럽의지배적세계관 유기적세계관 16C 와 17C 에근본적인변화 - 기계론적세계관으로대치과학혁명 코페르니쿠스로부터시작 - 태양중심설주장 갈릴레오갈릴레이 - 코페르니쿠스의가설을유효한과학적이론으로정립. 실험적접근법과자연의수학적기술이라는선구자적견해는 17C 의지배적과학사상. 르네데카르트 (René Descartes) 베이컨 (Francis Bacon) 귀납적방법론을제시. 고대로부터과학의목표 : 자연질서를이해하고자연과의조화로운생활을영위하는지혜를만드는것. 베이컨이후과학의목표 : 자연을지배하고통제하는지식의획득. 오늘날의과학기술은반생태계적목적을위해사용되고있음. 과학혁명이진행됨에따라유기체적자연관이기계론적자연관으로대치되었고, 서구문명의발전에있어서중요성을띠게된이대치는뉴턴과데카르트에의해시작되고완성된것이다. 현대철학의창시자이자수학자 전통적인지식을전연수용하지않았으며새로운사상체계를수립 데카르트의방법론 철저한회의 : 의심할수있는모든것을의심하다가더이상의심할수없는것에도달. 나는생각한다, 고로나는존재한다! 분석적 : 사상과문제를각부분으로분해하는이분석적인추리방법은과학에대한데카르트의가장큰공헌일것입니다. 방법론의지나친강조가과학에서의환원주의적태도를팽배하게함. 데카르트적세계관 데카르트 : 정신과물질은분리되어있고근본적으로상이한것으로보았다 서구사상에심대한영향을끼침 데카르트에게있어물질은하나의기계 자연환경에대한인간의태도에강한영향을줌 과학의목적은자연의지배와조종이며과학적지식은우리로하여금자연의주인소유자가되게함 데카르트는물질의기계관을생물속에도확대시킴 식물, 동물이단순한기계로간주됨 위대한과학 모든자연현상을단한가지기계적원리체계로설명을시도함 이러한데카르트의기계론적생명관은생명과학의발전에결정적인영향을주었지만모든것을기계로보려해서현대의많은질병을이해할수없게방해함 2

피에르가상디 (1592-1655) Pierre Gassendi, a priest, philosopher, and scientist. Revived the atomic theory (1650) Atoms are primordial, impenetrable, simple, unchangeable, and indestructible bodies, and the smallest bodies that can exist. Atoms possess motion. Atoms and vacuum, the absolutely full and the absolutely empty, are the only true principles and there is no third principle possible. Atoms differ in size, shape and weight. Atoms form very small corpuscles, or molecules, which aggregate into larger and larger bodies The Sceptical Chymist (1661). 보일의원자론 물질입자들은우리가감지할수없을정도로작다. 이입자는그자체로완전히분할되지않는것이기때문에확실한형태를가질수밖에없으며, 따라서상당히견고하지않으면안된다. 상상의세계나전능한신의힘에의해서라면모를까, 그극미함과견고함때문에자연계에서이것을분할하는일은현실적으로일어나지않는다. 이런의미에서이것을 미니마 또는 프리마나투랄리아 라고부른다. 미니마가모여있는입자도다수존재하는데이런입자의크기역시상당히작다. 따라서미니마사이의흡착력이극히밀접하고강력하다. 이것이프리마나투릴리아등의작은조각으로분할되는일은, 자연계에서절대로일어날수없다고말할수는없지만, 실제로이러한결합이분할된다거나부서지는경우는드물다. Atomic Age 원자시대 질량보존의법칙 Antoine Lavoisier, Réflexions sur le phlogistique (1783), 일정성분비의법칙 A French chemist Joseph Louis Proust(1754-1826) Published, 1798-1806. 1828(by Berzelius). Non-stoichiometric compounds. 예 Fe 1-x O, x = 0.05 Pierre Berthollet(1748 ~ 1822) 3

배수비례의법칙 John Dalton, a British chemist and physicist, 1804. If two elements combine to form more than one compound, then the ratio of the weights of the second element(which combines with a FIXED weight of the first element) will be small whole numbers. 부피결합의법칙 A French chemist Joseph Gay-Lussac(1778-1850) Published 1808, accepted by Cannizzaro in 1860 gases under equal conditions of temperature and pressure react with one another in volume ratios of small whole numbers. For example carbon oxide: CO and CO 2, 100 grams of carbon may react with 133 grams of oxygen( to produce carbon monoxide), or with 266 grams of oxygen(to produce carbon dioxide). Dalton 의원자가설 Dalton 의원자가설 New System of Chemical Philosophy (1808) 1. Matter consists of indivisible atoms. 2. All of the atoms of a given chemical element are identical in mass and in all other properties. 3. Different chemical elements have different kinds of atoms; in particular, their atoms have different masses. 4. Atoms are indestructible and retain their identities in chemical reactions. 5. A compound forms from its elements through the combination of atoms of unlike elements in small whole-number ratios. He deduced that all elements are composed of atoms. Atoms are indivisible and indestructible particles. Atoms of the same element are exactly alike. Atoms of different elements are different. Compounds are formed by the joining of atoms of two or more elements. Dalton s symbols, 1808 Dalton 의원자질량 1808 4

Jon Jakob Berzelius, 1813: Letters for element symbols Name Symbol Name Symbol Name Symbol Name Symbol Oxygen O Tungsten Tn Palladium Pa Uranium U Avogadro 의가설 In 1811, by the Italian chemist Armedeo Avogadro(1776-1856) Sulphur S Antimony Sb Silver Ag Cerium Ce Phosphorus P Tellurium Te Mercury Hg Yttrium Y Muriatic radicle (chlorine) Fluoric radicle M Columbium (nioblium) Cl Copper Cu Glucinum (beryllium) F Titanium Ti Nickel Ni Aluminum Al Boron B Zirconium Zr Cobalt Co Magnesium Ms Gl equal volumes of gases under equal conditions of temperature and pressure contain equal numbers of molecules. Carbon C Silicium Si Bismuth Bi Strontium Sr Nitric radicle N Osmium Os Lead Pb Barytium Ba Hydrogen H Iridium I Tin Sn Calcium Ca Arsenic As Rhodium Rh Iron Fe Sodium So Molybdenum Mo Platinum Pt Zinc Zn Potassium Po Chromium Ch Gold Au Manganese Ma Avogadro's ideas were ignored until reintroduced by Cannizzaro in 1860 Karlsruhe Congress(1860 년 9 월 ) Thomson 의첫번째실험 Karlsruhe, Germany, first international conference of chemistry worldwide. On the meeting's last day reprints of Stanislao Cannizzaro's 1858 paper on atomic weights, in which he utilized earlier work by Amedeo Avogadro, were distributed. Cannizzaro's efforts exerted a heavy and, in some cases, an almost immediate influence on the delegates. Lothar Meyer later wrote that on reading Cannizzaro's paper, "The scales seemed to fall from my eyes. atomic weights of 1 was adopted as the weight of hydrogen (the base unit), with 6 for carbon and 8 for oxygen 유명한참석자 :( 박영동교수선정 ). Belgium. A. Kekulé; Germany. Lothar Meyer, R. Bunsen( 분광학, 분젠버너 ), E. Erlenmeyer( 엘렌마이어플라스크 ); Italy. Cannizzaro; Russia. Borodin( 화학자겸작곡가 ), Mendeleev; Switzerland. H. Schiff(Schiff base); electrometer measures the charge transferred to the cylinder. J.J. Thomson, "Cathode Rays," The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science, Fifth Series, October 1897. p. 295 Thomson 의두번째실험 Thomson 의세번째실험 e/m = -1.759 x 10 8 coulomb/g - 1897 calculate the ratio of the mass of a particle to its electric charge (m/e) J.J. Thomson, "Cathode Rays," The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science, Fifth Series, October 1897. p. 296 J.J. Thomson, "Cathode Rays," The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science, Fifth Series, October 1897. p. 301 5

J. J. Thomson(1856-1940) 원자이론의변천 Aristotlelian Model Thomson Model 1897 Greek Model 400 BC Democritus Boyle Model 1661 Dalton Model 1803 Rutherford Model 1911 BohrModel 1922 Nobel Prize for Physics (1906) 러더포드의금박실험 러더포드의금박실험 In 1908, the English physicist Ernest Rutherford was hard at work on an experiment that seemed to have little to do with unraveling the mysteries of the atomic structure. Most of the positively charged bullets passed right through the gold atoms in the sheet of gold foil without changing course at all. Some of the positively charged bullets, however, did bounce away from the gold sheet as if they had hit something solid. He knew that positive charges repel positive charges. (2000 atoms thick) 러더포드의금박실험 This could only mean that the gold atoms in the sheet were mostly open space. Atoms were not a pudding filled with a positively charged material. Rutherford concluded that an atom had a small, dense, positively charged center that repelled his positively charged bullets. He called the center of the atom the nucleus The nucleus is tiny compared to the atom as a whole. 6

Rutherford(1871-1937) 밀리칸의기름방울실험 Nobel Prize in Chemistry (1908) Rutherford reasoned that all of an atom s positively charged particles were contained in the nucleus. The negatively charged particles were scattered outside the nucleus around the atom s edge. Robert Millikan(1868-1953) and Harvey Fletcher in 1909 Millikan s result : 4.774(5) 10 10 statc = 1.5924(17) 10 19 C. accepted value as of 2008 : 1.602176487(40) 10 19 C). Nobel prize in physics in 1923. Dalton s Atom 의한계 Henri Becquerel (1852-1908) Radiation activity, 1896 Inner structure of atom electron confirmed by J.J. Thomson(1897) Noble Prize in Physics(1906) Inner Structure of atom nucleus by Rutherford, Geiger, Marsden(1909). Rutherford was awarded Nobel Prize in Chemistry in 1908 for radioactivity. Inner Structure of nucleus proton - by Rutherford (1917-20) Inner Structure of nucleus neutron - by Chadwick (1932) Nobel Prize in Physics(1935) Radioactivity unstable nucleus by Becquerel(1896) Nobel Prize in Physics(1903) Image of potassium uranyl sulfate, K 2 UO 2 (SO 4 ) 2. Uranyl nitrate, UO 2 (NO 3 ) 2. Normal light (top) UV light (bottom) Pierre Curie (1859-1906) Marie Curie (1867-1934) Radioactivity- 1898 Polonium - 1898 Radium - 1898 Glenn T. Seaborg (1912-1999) Extending the periodic table http://www.chymist.com/extending the Periodic Table.pdf pitchblende Marie Curie with inset photo of Pierre Curie Radium bromide 7

Rutherford s Revised Atomic Theory (1911) Result: Most of the positively charged particles went straight through the gold foil. Atomic Theory: Most of the matter of the atom is found in a very small part of the atom. This is called the nucleus of the atom. It is very tiny and extremely dense. Result: Some of the positively charged particles were deflected or even bounced back. Atomic Theory: Like charges repel so the nucleus must have a positive charge. If electrons have a negative charge they could not be in a positively charged nucleus. Electrons must surround the nucleus at a distance. Result: The diameter of the nucleus is 100,000 times smaller than the diameter of the entire gold atom. Atomic Theory: Atoms are mostly empty space with a tiny, massive nucleus at the center. 원자핵 100,000배원자 성인 원자의크기 100,000배 100,000배수퍼박테리아, 위키피디아 원자에서의원자핵 Bohr 의모델 In 1913, the Danish scientist Niels Bohr proposed an improvement. In his model, he placed each electron in a specific energy level. The diameter of a pinhead is 100,000 times smaller than the diameter of a stadium. Likewise the diameter of the nucleus of an atom is 100,000 times smaller than the diameter of an atom The Bohr 의원자모델 What did Bohr learn about electron movement? 현대의원자이론 Bohr proposed that electrons move in paths at certain distances around the nucleus. Electrons can jump from a path on one level to a path on another level. Electrons travel in regions called electron clouds You cannot predict exactly where an electron will be found 8

Wave Model What can a scanning tunneling electron microscope show us? These images do not show an actual picture of an atom. They show a colorenhanced image of the surface of a material at the atomic level. Si(111) 의 STM 영상 M.F. Crommie, C.P. Lutz, D.M. Eigler. Confinement of electrons to quantum corrals on a metal surface. Science 262, 218-220 (1993) Highly Resolved STM and Non-Contact AFM on Si(111) 7x7 with Omicron VT AFM and Matrix SPM Control System 그래핀의 TEM 영상 from <http://www.popsci.com/gadgets/ article/2010-01/graphenebreakthrough-could-usher-futureelectronics> Greek Dalton Thomson Indivisible Electron Nucleus Orbit X X Rutherford X X Bohr X X X X Electron Cloud Wave X X X 9

원자설에대한논쟁 Boltzmann(1844-1906) vs. many Dalton's atomic theory remained controversial throughout the 19th Century. Whilst the law of definite proportion were accepted, the hypothesis that this was due to atoms was not so widely accepted. For example in 1826 when Sir Humphry Davy presented Dalton the Royal Medal from the Royal Society, Davy said that the theory only became useful when the atomic conjecture was ignored. Sir Benjamin Collins Brodie in 1866 described atomic theory as a 'Thoroughly materialistic bit of joiners work'. Alexander Williamson used his Presidential address to the London Chemical Society in 1869 to defend the atomic theory against its critics and doubters. This in turn led to further meetings at which positivists again attacked the supposition that there were atoms. Ernst Mach also opposed the atomic theory. The matter was finally resolved in Dalton's favor by Einstein's work on Brownian motion in the early 20th Century. Boltzmann's formulation of a statistical interpretation of thermodynamics was attacked because of his use of the neverbefore-seen-or-measured microscopic atoms of molecules. Boltzmann's critics were : Max Planck, Ernst Zermelo, Ernst Mach, and Friedrich Wilhelm Ostwald Boltzmann had the audacity to suggest matter was made of atoms. 볼츠만의죽음은이들의공격과도연관될수있다. Boltzmann vs. many Ostwald and Boltzmann at the Lübeck Scientific Conference in 1895. "The fight between Boltzmann and Ostwald was like the fight of a bull with a supple fighter. But this time the bull overcame the torero in spite of all his art in fencing. The arguments of Boltzmann won. We younger mathematicians were all on Boltzmann's side" 원자가설과파인만 If, in some cataclysm, all of scientific knowledge were to be destroyed, and only one sentence passed on to the next generations of creatures, what statement would contain the most information in the fewest words? I believe it is the atomic hypothesis (or the atomic fact, or whatever you wish to call it) that all things are made of atoms - Richard Feynman, in his book of the Feynman Lectures on Physics, vol.1 (Coveney and Highfield 1991, 175). 10