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1 우주와생명제 3 강 원자론

2 INTRODUCTION 노벨물리학상수상강연 (1926) 물질의불연속적구조 Discontinuous Structure of Matter 장페랑 Jean Baptiste Perrin

3-1 20 세기이전의원자론 (Atomic Theory before 20th Century) 공기나물과같은유체는첫눈에는완벽하게균일한것처럼보인다 ; 우리는유리잔에물을더담을수도있고덜담을수도있어서, 유리잔에들어있는물의양은무한히작은양만큼씩다를수있다, 그러니까물은무한히나눌수있는것처럼보인다.

3 세기이전의원자론 (Atomic Theory before 20th Century) 공기나물과같은유체는첫눈에는완벽하게균일한것처럼보인다 ; 우리는유리잔에물을더담을수도있고덜담을수도있어서, 유리잔에들어있는물의양은무한히작은양만큼씩다를수있다, 그러니까물은무한히나눌수있는것처럼보인다. A fluid such as air or water seems to us at first glance to be perfectly homogeneous; we can put more or less water into this glass, and the experiment seems to suggest to us that the amount of water contained in it can vary by an infinitely small amount, which is the same as saying that water is indefinitely divisible.

4 세기이전의원자론 (Atomic Theory before 20th Century) ( 고대의 ) 원자론자에게는모든물질은빈공간사이에존재하는 아주작은입자들로이루어졌다 ; 그러나이런입자들자체, 즉 우주를구성하는파괴할수없는원자들의구조에대해서는 아무런가설도제시된바없었다. For the atomists, all matter consists of minute grains separated by empty gaps; not any hypothesis has been formulated for the structure of these grains themselves, atoms, which were considered as indestructible constituent element of the Universe.

3-1 20 세기이전의원자론 (Atomic Theory before 20th Century) 지난세기 (19세기) 말에일부과학자들은우리입장에서어떻게보이는지가우리에게최종적으로중요한것이기때문에우리가접근할수없는영역에무엇이존재하는지를따지는것은무의미하다고생각했다.

5 세기이전의원자론 (Atomic Theory before 20th Century) 지난세기 (19세기) 말에일부과학자들은우리입장에서어떻게보이는지가우리에게최종적으로중요한것이기때문에우리가접근할수없는영역에무엇이존재하는지를따지는것은무의미하다고생각했다. 에른스트마하 Ernst Mach At the end of the last century, certain scholars considered that since the appearances on our scale were finally the only important ones for us, there was no point in seeking what might exist in an inaccessible domain.

3-1 20 세기이전의원자론 (Atomic Theory before 20th Century) ( 현미경의발명에서볼수있듯이 ) 오늘접근할수없는것을내일접근할수도있고, 또아직은볼수없는것에대한일관성있는가정이볼수있는것에대한이해를증진시킬수도있다는것을생각할때나는이런관점을도무지이해하기어렵다.

6 세기이전의원자론 (Atomic Theory before 20th Century) ( 현미경의발명에서볼수있듯이 ) 오늘접근할수없는것을내일접근할수도있고, 또아직은볼수없는것에대한일관성있는가정이볼수있는것에대한이해를증진시킬수도있다는것을생각할때나는이런관점을도무지이해하기어렵다. I find it very difficult to understand this point of view since what is inaccessible today may become accessible tomorrow (as has happened by the invention of the microscope), and also because coherent assumptions on what is still invisible may increase our understanding of the visible. Unsigned Italian Compound Microscope (circa early 1700s)

3-1 20 세기이전의원자론 (Atomic Theory before 20th Century) 돌턴은어떤물질은모두똑같고반응과정에서조각으로나누어지지않는, 그래서원자라고불리는입자들의일정한조합에의해만들어진다고가정했다.

7 세기이전의원자론 (Atomic Theory before 20th Century) 돌턴은어떤물질은모두똑같고반응과정에서조각으로나누어지지않는, 그래서원자라고불리는입자들의일정한조합에의해만들어진다고가정했다. Dalton supposed that a substance is formed by a definite variety of particles which are all identical and which cannot be cut into pieces in the reactions, and which for this reason are called atoms.

3-1 20 세기이전의원자론 (Atomic Theory before 20th Century) 수많은화합물에대해결정될수있는구조식들은성공적으로그화합물의성질을예측할수있기때문에, 유기화학자들이얻은수십만개의구조식은하나하나가모두원자론의지지근거가된다고말할수있다.

8 세기이전의원자론 (Atomic Theory before 20th Century) 수많은화합물에대해결정될수있는구조식들은성공적으로그화합물의성질을예측할수있기때문에, 유기화학자들이얻은수십만개의구조식은하나하나가모두원자론의지지근거가된다고말할수있다. The structural formulae can be determined for an enormous number of compounds, and with such success in regard to forecasting the properties that it could be said that the hundreds of thousands of structural formulae set up by the organic chemists constitute just as many arguments in favor of the atomic theory.

9 3-2 아보가드로의원리 (Avogadro s Principle) 아보가드로의가설 : 다른기체물질들이같은온도와압력에서같은부피를 차지한다면그들은모두같은개수의분자를포함한다. Avogadro s postulate, or hypothesis: When gaseous masses, at the same temperature and pressure, occupy equal volumes, they all contain the same number of molecules. Ne N2 H20 NH3

10 3-2 아보가드로의원리 (Avogadro s Principle) 어떤물질의 1 그램분자량을이루는 분자의수 N 을아보가드로수라고 한다. The number N of the molecules constituting any gram-molecule is Avogadro s number = Carbon Atom Avogadro s Number 1 mole of Carbon

11 3-3 분자의운동 (Molecular Motion) 나는아마도아보가드로의가설이 ( 현미경등을통해서 ) 볼수있는알갱이로 이루어진안정된유탁액에도적용되고, 그래서브라운운동에의해교란되는 알갱이하나하나가벽에충돌할때하나의분자로작용할것이라고생각했다. I have thought that it was perhaps valid for stable emulsions with visible grains, in such manner that each of these grains which is agitated by the Brownian movement counts as a molecule when it collides with a wall.

12 3-3 분자의운동 (Molecular Motion) 나는 (1908년에) 정성적으로잘알려진사실, 즉평형상태에서는기체의수직기둥에서고도가높아질수록밀도가낮아진다는사실을유탁액에적용하였다. I extended (1908) to emulsions the fact that is qualitatively well known to you, that in a vertical column of a gas in equilibrium the density decreases as the altitude increases. 압력 고도

13 3-3 분자의운동 (Molecular Motion) 커다란수직펌프에서평형상태에있는수평방향의얇은공기층은바닥면에서의압력에해당하는압력을아래에서위로가하는피스톤과윗면에서의압력에해당하는압력을위에서아래로가하는피스톤사이에갇혀있다면평형상태를유지할것이고, Each horizontal slice of a gas in equilibrium in a large vertical pump would remain in equilibrium if it were imprisoned between two rigid pistons and these pistons would exert respectively the pressures existing at the lower face and at the upper face of the slice;

14 3-3 분자의운동 (Molecular Motion) 결과적으로단위면적당이두 압력의차이는공기층의무게가 된다. with the result that, per unit surface, the difference of these pressures is equal to the weight of the gas supported. P 2 P 1 - P 2 = 공기층의무게 / 면적 P 1

15 3-3 분자의운동 (Molecular Motion) 분자의개수 n 이주어진온도에서압력 p 에비례하기때문에, 주어진 기체의균일한온도의기둥에대해서는고도의차이가 dh 로같으면압력의 상대적감소 dp/p, 또는분자수의상대적감소 dn/n 는고도에상관없이 같은값을가진다. As the abundance n of molecules is proportional to the pressure p at each given temperature, we see that for a column of a given gas and of uniform temperature, the relative reduction of the pressure dp/p, or also the relative reduction of the abundance dn/n which can be said to measure the rarefaction, always has the same value for the same difference in level dh, whatever this level may be.

16 3-3 분자의운동 (Molecular Motion) 산소의경우에는 0 도에서매 5 킬로미터마다두배씩희박해진다. 수소의경우에는희박정도가두배되려면산소보다 16 배, 그러니까 80 킬로미터를올라가야한다. In oxygen at 0 o the rarefaction will be doubled for each rise of 5 kilometers. It is necessary to rise 16 times higher in hydrogen than in oxygen, i.e. 80 kilometers, for the rarefaction to be doubled. 분자량 = m 분자량 = 2m

$I treated in my most careful fractionation one kilogram of gamboge and obtained after several months of daily$

17 3-4 아보가드로수 (Avogadro's Number) 나의가장정밀한실험에서나는 1 킬로그램의 갬부지 ( 자황 ) 수지를처리해서몇달동안하루 종일작업하여몇백밀리그램의지름이 약 0.75 마이크로미터로균일한구형알갱이들을 얻었는데, 이크기는내가원했던적당한크기였다. I treated in my most careful fractionation one kilogram of gamboge and obtained after several months of daily operations a fraction containing several decigrams of grains with a diameter of approximately three-quarters of a thousandth of a millimeter which was appreciably equal to what I had wanted to obtain.

슬라이드커버유리유탁액현미경 To study the equilibrium distribution of the emulsion

18 3-4 아보가드로수 (Avogadro's Number) 중력하에서유탁액의평형분포를조사하기위해서현미경으로관찰할수있도록장치된잘막힌유리판사이에유탁액한방울을집어넣었다. 슬라이드커버유리유탁액현미경 To study the equilibrium distribution of the emulsion under the action of gravity, we imprisoned a drop of the emulsion in a wellclosed dish arranged for microscopic observation.

19 3-4 아보가드로수 (Avogadro's Number) 처음에는알갱이들이골고루분포되어있지만점차아래쪽에모이면서, 온도가내려가고올라감에따라가라앉고팽창하면서최종분포에도달한다. The distribution of the grains is at first uniform, but it is found that the grains accumulate progressively in the lower layers until a limiting distribution is reached with reversible settling or expansion depending on whether the temperature is lowered or raised.

20 3-4 아보가드로수 (Avogadro's Number) 유탁액이희박해지는정도는높이로부터금방구할수있고, 미니대기와의유사성은매우놀라운데인스턴트사진을찍으면정밀한측정이가능하다. 완벽한성공이다. The rarefaction of the emulsion is obtained immediately from the height, and the resemblance to a miniature atmosphere is extremely striking, precise measurements being possible from instantaneous photographs. The success is complete.

21 3-4 아보가드로수 (Avogadro's Number) 1911 Solvay Conference 앞줄왼쪽에서 6 번째가페랑

3-4 아보가드로수 (Avogadro's Number) 나의가장정밀한측정에서는 6 마이크론높아질때마다절반으로희박해졌는데이때 ( 아보가드로수 ) N 이 68 x 10 22 로얻어졌다.

22 3-4 아보가드로수 (Avogadro's Number) 나의가장정밀한측정에서는 6 마이크론높아질때마다절반으로희박해졌는데이때 ( 아보가드로수 ) N 이 68 x 로얻어졌다. My most careful measurements made with an emulsion the rarefaction of which doubled with each rise of 6 microns, gave a value for N of 68 x

23 Review To make Homo sapiens You need ten thousand moles Of atoms Of hydrogen And oxygen As well as carbon, nitrogen And phosphorus.

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untitled Chapter 5 Gases 3 5.1 2 NaN 3 (s) 2Na(s) + 3N 2 (g) Air bag 45.5L sodium azide?,,? 3 5.2 ? 1.,,, 2. P, V, n, T ( ) 3. 3 5.3 5.1,, = 1L = 10 3 cm 3 = 10-3 m 3 m=m n ( ) T k = t c + 273.15 : psi, mmhg, atm(