The Atomic Nature of Matter

Discussion

atoms do exist

What belongs in this section? Just chemistry? Or chemistry and physics?

We need to have the talk.

ἄ τομος, a tomos, uncuttable

Democritus, Dalton, Mendeleev, Avogadro, Priestly?, Boltzmann, Laue, STM/AFM images

The idea of atoms is very old. (Well, maybe just old.) The evidence for atoms is not that old, however.

Water would not move from place to place if it were not that it seeks the lowest level and by a natural consequence it never can return to a height like that of the place where it first on issuing from the mountain came to light. And that portion of the sea which, in your vain imagining, you say was so high that it flowed over the summits of the high mountains, for so many centuries would be swallowed up and poured out again through the issue from these mountains. You can well imagine that all the time that Tigris and Euphrates have flowed from the summits of the mountains of Armenia, it must be believed that all the water of the ocean has passed very many times through these mouths. And do you not believe that the Nile must have sent more water into the sea than at present exists of all the element of water? Undoubtedly, yes. And if all this water had fallen away from this body of the earth, this terrestrial machine would long since have been without water. Whence we may conclude that the water goes from the rivers to the sea, and from the sea to the rivers, thus constantly circulating and returning, and that all the sea and the rivers have passed through the mouth of the Nile an infinite number of times.

Leonardo da Vinci, ca. 1500s

 

Everything goes somewhere. Nothing disappears

Beakman.

 

A physicist is the atoms' way of thinking about atoms.

Anonymous

 

Like Avogadro's name, this quote is too long.

M. Gay-Lussac has shown in an interesting Memoir that gases always unite in a very simple proportion by volume, and that when the result of the union is a gas, its volume also is very simply related to those of its components. But the quantitative proportions of substances in compounds seem only to depend on the relative number of molecules which combine, and on the number of composite molecules which result. It must then be admitted that very simple relations also exist between the volumes of gaseous substances and the numbers of simple or compound molecules which form them. The first hypothesis to present itself in this connection, and apparently even the only admissible one, is the supposition that the number of integral molecules in any gases is always the same for equal volumes, or always proportional to the volumes. Indeed, if we were to suppose that the number of molecules contained in a given volume were different for different gases, it would scarcely be possible to conceive that the law regulating the distance of molecules could give in all cases relations so simple as those which the facts just detailed compel us to acknowledge between the volume and the number of molecules. On the other hand, it is very well conceivable that the molecules of gases being at such a distance that their mutual attraction cannot be exercised, their varying attraction for caloric may be limited to condensing a greater or smaller quantity around them, without the atmosphere formed by this fluid having any greater extent in the one case than in the other, and, consequently, without the distance between the molecules varying; or, in other words, without the number of molecules contained in a given volume being different. Dalton, it is true, has proposed a hypothesis directly opposed to this, namely, that the quantity of caloric is always the same for the molecules of all bodies whatsoever in the gaseous state, and that the greater or less attraction for caloric only results in producing a greater or less condensation of this quantity around the molecules, and thus varying the distance between the molecules themselves. But in our present ignorance of the manner in which this attraction for the molecules for caloric is exerted, there is nothing to decide us a priori in favour of the one of these hypotheses rather than the other; and we should rather be inclined to adopt a neutral hypothesis, which would make the distance between the molecules and the quantities of caloric vary according to unknown laws, were it not that the hypothesis we have just proposed is based on that simplicity of relation between the volumes of gases on combination, which would appear to be otherwise inexplicable.

Setting out from this hypothesis, it is apparent that we have the means of determining very easily the relative masses of the molecules of substances obtainable in the gaseous state, and the relative number of these molecules in compounds; for the ratios of the masses of the molecules are then the same as those of the densities of the different gases at equal temperature and pressure, and the relative number of molecules in a compound is given at once by the ratio of the volumes of the gases that form it. For example, since the numbers 1.10359 and 0.07321 express the densities of the two gases oxygen and hydrogen compared to that of atmospheric air as unity, and the ratio of the two numbers consequently represents the ratio between the masses of equal volumes of these two gases, it will also represent on our hypothesis the ratio of the masses of their molecules. Thus the mass of the molecule of oxygen will be about 15 times that of the molecule of hydrogen, or more exactly, as 15.074 to 1. In the same way the mass of the molecule of nitrogen will be to that of hydrogen as 0.96913 to 0.07321, that is, as 13, or more exactly 13.238, to 1. On the other hand, since we know that the ratio of the volumes of hydrogen and oxygen in the formation of water is 2 to 1, it follows that water results from the union of each molecule of oxygen with two molecules of hydrogen. Similarly, according to the proportions by volume established by M. Gay-Lussac for the elements of ammonia, nitrous oxide, nitrous gas, and nitric acid, ammonia will result from the union of one molecule of nitrogen with three of hydrogen, nitrous oxide from one molecule of oxygen with two of nitrogen, nitrous gas from one molecule of nitrogen with one of oxygen, and nitric acid from one of nitrogen with two of oxygen.

Lorenzo Romano Amadeo Carlo Avogadro, 1811

1
H
1.0079
           
2
He
4.0026
3
Li
6.941
4
Be
9.0122
         
5
B
10.811
6
C
12.011
7
N
14.007
8
O
15.999
9
F
18.998
10
Ne
20.180
11
Na
22.990
12
Mg
24.305
         
13
Al
26.982
14
Si
28.086
15
P
30.974
16
S
32.066
17
Cl
35.453
18
Ar
39.948
19
K
39.098
20
Ca
40.078
21
Sc
44.956
22
Ti
47.867
23
V
50.942
24
Cr
51.996
25
Mn
54.938
26
Fe
55.845
27
Co
58.933
28
Ni
58.693
29
Cu
63.546
30
Zn
65.39
31
Ga
69.723
32
Ge
72.61
33
As
74.922
34
Se
78.96
35
Br
79.904
36
Kr
83.80
37
Rb
85.468
38
Sr
87.62
39
Y
88.906
40
Zr
91.224
41
Nb
92.906
42
Mo
95.94
43
Tc
(98)
44
Ru
101.07
45
Rh
102.91
46
Pd
106.42
47
Ag
107.87
48
Cd
112.41
49
In
114.82
50
Sn
118.71
51
Sb
121.76
52
Te
127.60
53
I
126.90
54
Xe
131.29
55
Cs
132.91
56
Ba
137.33
71
Lu
174.97
72
Hf
178.49
73
Ta
180.95
74
W
183.84
75
Re
186.21
76
Os
190.23
77
Ir
192.22
78
Pt
195.08
79
Au
196.97
80
Hg
200.59
81
Tl
204.38
82
Pb
207.2
83
Bi
208.98
84
Po
(209)
85
At
(210)
86
Rn
(222)
87
Fr
(223)
88
Ra
(226)
103
Lr
(262)
104
Rf
(261)
105
Db
(262)
106
Sg
(263)
107
Bh
(264)
108
Hs
(265)
109
Mt
(268)
110
Ds
(281)
111
Rg
(272)
112
Cn
(277)
113
Uut
(284)
114
Fl
(289)
115
Uup
(288)
116
Lv
(292)
117
Uus
(293)
118
Uuo
(294)
119
Uue
(???)
120
Ubn
(???)
           
   
57
La
138.91
58
Ce
140.12
59
Pr
140.91
60
Nd
144.24
61
Pm
(145)
62
Sm
150.36
63
Eu
151.96
64
Gd
157.25
65
Tb
158.93
66
Dy
162.50
67
Ho
164.93
68
Er
167.26
69
Tm
168.93
70
Yb
173.04
   
   
89
Ac
(227)
90
Th
232.04
91
Pa
231.04
92
U
238.03
93
Np
(237)
94
Pu
(244)
95
Am
(243)
96
Cm
(247)
97
Bk
(247)
98
Cf
(251)
99
Es
(252)
100
Fm
(257)
101
Md
(258)
102
No
(259)
   
121
Ubu
(???)
122
Ubb
(???)
123
Ubt
(???)
124
Ubq
(???)
125
Ubp
(???)
126
Ubh
(???)
127
Ubs
(???)
128
Ubo
(???)
129
Ube
(???)
130
Utn
(???)
131
Utu
(???)
132
Utb
(???)
133
Utt
(???)
134
Utq
(???)
135
Utp
(???)
136
Uth
(???)
137
Fy
(???)
138
Uto
(???)
symbol name   symbol name   symbol name
Ac Actinium   H Hydrogen   Ra Radium
Ag Silver   He Helium   Rb Rubidium
Al Aluminum   Hf Hafnium   Re Rhenium
Am Americium   Hg Mercury   Rf Rutherfordium
Ar Argon   Ho Holmium   Rg Roentgenium
As Arsenic   Hs Hassium   Rh Rhodium
At Astatine   I Iodine   Rn Radon
Au Gold   In Indium   Ru Ruthenium
B Boron   Ir Iridium   S Sulfur
Ba Barium   K Potassium   Sb Antimony
Be Beryllium   Kr Krypton   Sc Scandium
Bh Bohrium   La Lanthanum   Se Selenium
Bi Bismuth   Li Lithium   Sg Seaborgium
Bk Berkelium   Lr Lawrencium   Si Silicon
Br Bromine   Lu Lutetium   Sm Samarium
C Carbon   Lv Livermorium   Sn Tin
Ca Calcium   Md Mendelevium   Sr Strontium
Cd Cadmium   Mg Magnesium   Ta Tantalum
Ce Cerium   Mn Manganese   Tb Terbium
Cf Californium   Mo Molybdenum   Tc Technetium
Cl Chlorine   Mt Meitnerium   Te Tellurium
Cm Curium   N Nitrogen   Th Thorium
Cn Copernicium   Na Sodium   Ti Titanium
Co Cobalt   Nb Niobium   Tl Thallium
Cr Chromium   Nd Neodymium   Tm Thulium
Cs Cesium   Ne Neon   Uuo Ununoctium
Cu Copper   Ni Nickel   Uup Ununpentium
Ds Darmstadtium   No Nobelium   Uus Ununseptium
Db Dubnium   Np Neptunium   Uut Ununtrium
Dy Dysprosium   O Oxygen   U Uranium
Er Erbium   Os Osmium   V Vanadium
Es Einsteinium   P Phosphorus   W Tungsten
Eu Europium   Pa Protactinium   Xe Xenon
F Fluorine   Pb Lead   Y Yttrium
Fe Iron   Pd Palladium   Yb Ytterbium
Fm Fermium   Pm Promethium   Zn Zinc
Fr Francium   Po Polonium   Zr Zirconium
Fl Flerovium   Pr Praseodymium      
Fy Feynmanium   Pt Platinum      
Ga Gallium   Pu Plutonium      
Gd Gadolinium  
Ge Germanium  
Symbols of the elements