Lecture 66 min.
Chemistry
D.I. Mendeleev: "The immediate subject of chemistry is the study of homogeneous
substances, from the combination of which all the bodies of the world are composed, their transformations into one another, and
the phenomena accompanying such transformations."
A set of definitions from the Chemical Encyclopedia:
(For earlier definitions see Supplement 1)
Substance is a kind of matter that has rest mass. It consists of
elementary particles: electrons, protons, neutrons, mesons, and others. Chemistry studies
mainly substance organized into atoms, molecules, ions, and radicals. Such
substances are customarily divided into simple and complex (chemical compounds).
Simple substances are formed by atoms of one chemical element and therefore
are the form of its existence in the free state, e.g. sulfur, iron, ozone,
diamond. Complex substances are formed by different elements and may have a composition that is
constant (stoichiometric compounds, or daltonides) or varies within
certain limits (nonstoichiometric compounds, or berthollides).
Atom (from Greek atomos – indivisible) is the smallest particle of a chemical element,
the carrier of its properties. To each chemical element corresponds a set of
certain atoms.
Chemical elements are sets of atoms with a definite nuclear charge Z.
D.I. Mendeleev defined chemical elements thus: "the material parts of simple or complex bodies
which impart to them a certain set of physical and chemical properties."
The forms of existence of chemical elements in the free state are simple substances.
Molecule (New Latin molecula, diminutive of Latin moles – mass) is a microparticle
formed from two or more atoms and capable of independent
existence. It has a constant composition (qualitative and quantitative) of the atomic nuclei entering
into it and a fixed number of electrons, and possesses a set of
properties that make it possible to distinguish one molecule from others, including from molecules of the same
composition.
Ions (from Greek ion – going) are monatomic or polyatomic particles
carrying an electric charge. Positive ions are called cations (from Greek
kation, literally – going down), negative ones – anions (from Greek anion, literally
going up). In the free state they exist in the gas phase (in plasma).
Valence (from Latin valentia – strength) is the ability of an atom to attach or
replace a certain number of other atoms or atomic groups with the formation of
a chemical bond. The quantitative measure of the valence of an atom of element E is the number of
hydrogen or oxygen atoms (these elements are conventionally considered to be mono- and
divalent, respectively) that E attaches, forming a hydride EHx or an oxide EnOm.
2
The valence of an element can also be determined from other atoms of known
valence. …
Within the framework of the electronic theory of chemical bonding, the valence of an atom is determined by
the number of its unpaired electrons in the ground or excited state,
participating in the formation of shared electron pairs with electrons of other atoms.
In chemistry the concept of "valence" is just as relative as "energy" is in physics.
Let us try to estimate the energy of a glass of water standing on a table. This is, first of all, the
potential energy of 180 g of water (for simplicity, 10 mol). But it is also the possible energy
that would be released from the protons of water during nucleosynthesis:
4 1H → 4He + 26.7 MeV
1 eV = 96.48 kJ/mol; 1 MeV = 96480000 kJ/mol
Chemical reactions (from Latin re- – a prefix meaning reverse action, and
actio – action) are transformations of some substances (starting compounds) into others
(reaction products) with the nuclei of the atoms remaining unchanged.
The starting substances are sometimes called reagents, but more often (especially in
organic chemistry) the term "reagent" is used for one, the most
active starting compound, which determines the direction of the chemical reaction.
The chemical reaction equation – model and reality
Chemical reactions by no means always strictly correspond to carefully
balanced equations. Rather the opposite – in most cases the equation reflects
either the main process or the most desirable one.
For example, the reactions of dissolution of many metals in
nitric acid cannot be described by a single equation – the formation of NO2, NO,
N2O, N2, NH4NO3 proceeds simultaneously.
In some chemistry textbooks and manuals one can find the equation of
the combustion of black (smoky) powder – the most ancient military explosive
substance:
2 KNO3 + S + 3 C = K2S + 3 CO2 + N2
The left-hand side of the equation approximately reflects the composition of real powders. However, the right-hand
side does not agree with experimental data. In the combustion products of black
powder at least 8 solid and 6 gaseous substances have been found. The authors of a book
aimed at practitioners propose an equation that is more
consistent with reality but does not meet the accepted rules of notation (free
carbon and sulfur on the left and on the right):
74 KNO3 + 96 C + 30 S + 16 H2O = 35 N2 + 56 CO2 + 14 CO + 3 CH4 + 2 H2S + 4 H2 +
+ 19 K2CO3 + 7 K2SO4 + 8 K2S2O3 + 2 K2S + 2 KSCN + (NH4)2CO3 + C + S
The presence of water on the left is not surprising, since in the brown charcoal used in the
production of black powder the carbon content usually does not exceed 75%; such
charcoal contains fragments of cellulose molecules. Moreover, as early as the 19th century a considerable
dependence of the composition of the combustion products of
black powder on pressure was discovered and investigated – consequently, the equation depends on the conditions
under which the reaction is carried out.
In general, the tradition of reducing chemical processes precisely to equations rather than to
schemes of chemical reactions (schoolchildren and university applicants suffer most from this)
corresponds only to the chemistry of compounds of constant composition
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(daltonides). The overwhelming majority of chemical reactions cannot be described
by equations 100%, so they are usually divided into main and side reactions.
This applies especially to organic chemistry.
Size effects. Nanochemistry
Internet lectures on nanotechnology: The Nanoworld in Which We Live, April 13, 2006
http://www.gazeta.ru/science/2006/04/13_a_586116.shtml
Technological prerequisites for the emergence of the "nanosciences."
In 1959 the first planar transistor appeared. In 1965 integrated circuits
consisting of 50-60 transistors were already being produced. Forty years ago Gordon Moore, co-founder of
Intel, suggested that the speed of computers and the
number of elements on a chip that provides it would double every 18 months without
a significant change in price. According to his forecast, this trend was supposed to
last for 10 years, and in 1975 everyone discovered that the forecast was coming true.
The atomic-molecular and electronic structure of chemical particles and substances is
a classical problem of chemical physics.
Because of size effects, the chemistry of small particles is singled out – clusters
containing from a few atoms or molecules to several tens. Example:
the ionization potentials of the water molecule, its dimer, and ice are, respectively, 12.6;
11.1, and 8.8 eV. Such special properties of small water associates undoubtedly have
great importance in living objects – in intracellular processes. The ionization
potential of Nan clusters decreases slowly with increasing n, and this decrease
is accompanied by oscillations; the even members of the series have a higher potential than
the odd ones, but even for the Na14 cluster the ionization potential is one and a half times greater than the work
function of the electron for metallic sodium [7, p. 1601].
If a particle of a substance has dimensions smaller than
1000 nm (i.e. less than 10-6 m) in at least one of the three dimensions, the fraction of surface
atoms or molecules in it increases substantially compared with atoms (molecules) in the bulk; in this case
one speaks of nanoparticles. It is known from the school physics course that surface
atoms (molecules) possess some excess energy compared with
larger, which gives rise to surface tension and the capillary effect. In
metal nanoparticles the mean free path of the electron is limited compared
with that in ordinary ("compact") metal. As a result, in materials made up
of nanoparticles the mechanical, electrical, magnetic and optical properties
cease to be constants – they depend on the size and shape of the particles. The dimensions
of features in modern microprocessors have already come close to 1000 nm (1 micron), and
designers have to investigate anew all the properties of the materials (metals,
semiconductors, insulators) used in microelectronics [8,9].
Chemical evolution of matter
The origin of the chemical elements and of planet Earth.
Chemistry as it is studied at school and in general university
courses is an exclusively terrestrial science. On the surface of the Sun it makes no sense to speak of
chemistry, because there are no molecules. Under the conditions of cosmic vacuum and low
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temperatures, and deep inside the Earth, many reactions also differ greatly from those that occur in
laboratories under "standard conditions".
In modern science the origin of matter is usually explained within the framework of
the "Big Bang" theory.
Until the middle of the 20th century, scientists regarded eternal matter in an eternal
Universe as a whole. Now it is assumed, and not only in the Bible, that the Universe had a beginning.
The modern picture of the Universe began to emerge only in 1924.
The American astronomer Edwin Hubble (1889-1953) calculated the distances to 9 different
galaxies by extrapolating the luminosity of known nearby stars to much more distant ones
(more precisely, he found variable stars in distant galaxies – Cepheids, for
which the dependence of luminosity on pulsation period is known) [10]. First he
determined the size of the Andromeda nebula and the distance to it (about 2 million light
years). As a result of spectral studies of starlight, in 1929 Hubble found
that the magnitude of the red shift of the spectra (toward longer wavelengths) increases
with the distance from us to stars and galaxies. That is, the farther away a galaxy is, the faster
it recedes from us! A similar phenomenon is modeled by the behavior of points on the surface of
an inflating balloon. In this way the expansion of the Universe was discovered.
Hubble himself could not immediately grasp that he had "crushed" the unchanging Universe.
As late as 1934 he tried to postulate a physical process, as yet unknown,
that would explain the apparent scattering of the galaxies. The first to realize that Hubble's results were
proof of a beginning was the abbé Georges Lemaître (1894-1966) in 1927,
who obtained from Einstein's cosmological equations a formula for the rate of
expansion of the Universe. [11]
However, the expansion of the Universe was predicted theoretically in 1922 by Alexander Alexan-
drovich Friedmann (1888-1925) on the basis of the general theory of relativity. Einstein
himself at first rejected Friedmann's results as "purely speculative" and
accepted them only in the 1930s. Hubble's discovery confirmed Friedmann's model. Friedmann's
theory made it possible to construct three models:
1) Big Bang ⇒ Big Crunch (expansion – contraction);
2) Big Bang ⇒ expansion with a speed decreasing to a constant value;
3) Big Bang ⇒ expansion with a constantly decreasing speed.
To choose the model precisely, one must know very accurately the present rate of expansion and
the average density of the Universe. The uncertainty in the measurement of distances and,
accordingly, of the rate of expansion is about 5%; the average density is determined
much less accurately (there is no guarantee that all forms of matter to which mass can be
ascribed are known). The average density of the observable
Universe determined to date is about 100 times lower than is required for the pulsating model (1).
The alternative to the absence of mass for a possible later contraction of the Universe is
a violation of the law of universal gravitation at large distances. But it is much easier
psychologically to assume a mass not yet found than a violation of a law that is so obvious in
the solar system. It is quite possible to allow for a model intermediate
between Friedmann's model (1) and models (2,3) – gradually damped pulsations. However,
even in the case of a single expansion one should expect small stars (of the Sun's type)
to burn out only after 10^14 years, which is 1000 times greater than the age of the Universe. The time ranges
for the other models are even larger.
Consequently, our world has a beginning – 15-20 billion years ago the
Big Bang occurred (measurements of 1995 give 10-12 billion years [12]). The Big Bang theory was almost
rejected in 1947, when the age of the Earth was estimated reliably enough (from data on
the decay of uranium) – the Earth turned out to be almost twice as "old" as the time calculated by Hubble for the
onset of the scattering of the galaxies. But by 1952 the color-
luminosity curves were recalibrated and the discrepancy was eliminated.
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In 1951 the Catholic Church officially recognized that the Big
Bang model is consistent with the Bible. In 1981 another conference on cosmology was organized at the Vatican,
and the head of the Catholic Church, the Pope, said that the domain of
science is everything that happened after the Big Bang, but that scientists should not intrude on
the divine act of Creation itself.
The first independent proof of the Big Bang theory was obtained in
1965.
Different mechanisms of the explosion itself are possible. The "hot Universe" model was
proposed by the American George (Georgy Antonovich) Gamow (1904-1968), a student of
A.A. Friedmann, in 1940 [13]. The glow of the incandescent early Universe could reach
us now strongly red-shifted – to the microwave (SHF)
range. The relic radio emission predicted by Gamow (photons just slightly warmer than 0
K) was discovered in 1965. The Americans Arno Penzias and Robert Wilson were testing a new,
very sensitive microwave detector for communication with artificial Earth satellites and
found a noise level higher than calculated. After careful measurements it became clear
that the source of this noise is the same in all directions and lies outside
our Galaxy. This was proof of the hypotheses of Friedmann and Gamow of a uniform
expansion of the Universe as a result of a hot explosion. In 1978 A. Penzias and R. Wilson
received the Nobel Prize.
It is precisely 1965 that should be regarded as the beginning of the collapse of the steady-state Universe theory
in the minds of most scientists.
Thus the model of the eternal Universe had to be replaced by the long-known
model (Genesis 1, 1-5):
In the beginning God created the heaven and the earth.
And the earth was without form, and void; and darkness was upon the face of the deep. And the Spirit of God moved upon the face of the
waters.
And God said, Let there be light: and there was light.
And God saw the light, that it was good: and God divided the light from the darkness.
And God called the light Day, and the darkness he called Night. And the evening and the morning were the first day.
Friedmann's models assume a singularity (what it is, is unknown in
principle). This is a point where the density and the curvature of space-time are infinite, i.e.
of zero size. Big Bang theories without a singularity are much less probable
(E.M. Lifshitz and I.M. Khalatnikov, 1963-1970).
It should be emphasized that the Big Bang theory (the singularity and the beginning of
time) follows from the general theory of relativity (Roger Penrose's theorem on the collapse of a star into a black hole – 1965;
the joint theorem of Stephen Hawking and
Penrose – 1970). But in the singularity general relativity comes into conflict with the requirements of
quantum mechanics (the dimensions are infinitely small). Cosmology required the joint
consideration of these incompatible theories.
The development of the Universe (according to G. Gamow, 1948).
At the moment of the Big Bang the size of the Universe was zero, and the temperature was
infinitely high (10^26 degrees – the level of the "countdown" accessible to theories,
corresponding to a time of 10^-43 seconds). After one second the temperature fell to ten
billion degrees (such a temperature is possible in the explosion of a hydrogen bomb). The Universe
then consisted of photons, electrons and neutrinos, a small number of protons and
neutrons, and their antiparticles.
At first there was only "light". For radiation to turn into matter
(the process inverse to annihilation), the energy of a photon producing a particle-
antiparticle pair must exceed E = 2 mc2 (where m is the rest mass of the particle). The temperature
corresponding to this energy is T = 2 mc2/k, where k is the Boltzmann constant =
6
0.00008617 eV/K. The threshold temperature for the production of electron-positron pairs (the mass of e-
corresponds to an energy of 0.511 MeV) is 6·10^9 K.
The process of the appearance of matter from primordial radiation was described long ago (Genesis 1, 6-
10):
And God said, Let there be a firmament in the midst of the waters, and let it divide the waters from the waters.
And God made the firmament, and divided the waters which were under the firmament from the waters which were
above the firmament: and it was so.
And God called the firmament Heaven. And the evening and the morning were the second day.
And God said, Let the waters under the heaven be gathered together unto one place,
and let the dry land appear: and it was so.
And God called the dry land Earth; and the gathering together of the waters called he Seas: and God saw that it was
good.
The same passage in the Torah (Bereshit 1, 6-8):
And the Almighty said: "Let there be an expanse in the midst of the waters, and let it divide
the waters from the waters."
And the Almighty made the expanse, and divided between the waters which were under
the expanse and the waters which were above the expanse; and it was so.
And the Almighty called the expanse heaven. And the evening and the morning were the
second day.
According to Gamow's calculations, in the initial mixture of particles there had to be about 40 million photons for each proton,
neutron and electron. The initial
balance of particles and antiparticles differed by about one billionth
(one ten-billionth) in favor of particles, which led to our Universe. After a hundred
seconds the temperature had fallen to a billion degrees, and the first
atomic nuclei began to appear – deuterium, helium, then lithium and beryllium). A few hours after the
Big Bang new elements ceased to form.
The standard model (standard scenario) is a theory developed in detail,
starting from 0.01 s – the time when an equilibrium "gas" arose, in which the
earlier stages are not visible. The temperature is 10^11 K, and the fraction of neutrons is about 46% of the sum of protons and
neutrons. Assuming that the size of the Universe is inversely proportional to the
temperature (the present relic temperature is 3 K, and the "circumference" is about 125 billion
light years), we obtain that at 10^11 K the circumference is 4 light years [14]. That is, the
rate of "expansion" is 0.65 light years (radius) in 0.01 second. Such a
significant excess over the speed of light is due to the fact that space
itself is being created [15].
After about 3 min 2 s the temperature fell to 1 billion (10^9) degrees,
and nuclei began to form. The proton/neutron ratio = 8:1, and it has been preserved.
For the next 500 thousand years there was no change.
The Universe is a mixture of leptons (neutrinos and antineutrinos),
relic radiation (photons) and baryons (hydrogen, helium, and very small amounts of their isotopes) [16].
The four fundamental interactions give no prerequisites for further
development [17]. The structuring of the Universe before the formation of stars took up to 3 billion years
[18].
After a million years individual regions began to contract again, forming gas
clusters, and then inside these clusters (the future galaxies) stars began to appear.
Heavier stars sometimes exploded (supernovae), supplying the galaxies with heavy
elements. Then the process of contraction of clouds of cosmic gas began again. Our
Sun is a star of the second or third generation, formed about five
7
billion years ago. The temperature ranges of the synthesis of elements (nuclei) [19]
are as follows: at a temperature of the center of the Sun of about 15 million °C only the synthesis of helium
from hydrogen takes place; at 100 million °C helium nuclei fuse into carbon; with a further rise in
temperature in the center of the star to 600 million °C magnesium begins to be synthesized from carbon;
at 200 million °C sulfur is formed from magnesium, and at 4000 million °C iron is
synthesized from sulfur atoms (the processes are complex and multistage). However, by the end of the
synthesis of helium from hydrogen the star has spent about 2/3 of its nuclear energy. The synthesis of
heavier elements already requires an inflow of energy, which arises during rapid
collapse into a white dwarf, especially at the stage of its explosion (supernova) [20].
The origin of the chemical elements according to the standard model
Table 1*. Primary nucleosynthesis
Age
of the Universe
Temperature,
K
State and composition of matter
10^-2 s 10^11
n, p, e-, e+, ν, ν– in thermal equilibrium; n and p in
equal numbers
10^-1 s 3*10^10
The same particles as above, but the ratio of the number of
neutrons to the number of protons is n : p = 3 : 5
1 s 10^10
ν, ν– decouple from the other particles; e-, e+ begin to
annihilate; n : p = 1 : 3
13.8 s 3*10^9
The formation of D and 4He begins; e-, e+ disappear; free n and p
are also present
35 min 3*10^8
The amounts of D and 4He relative to the number of
protons and electrons become fixed; 4He / H ~ 22-28% (by mass)
7*10^5 years 3*10^3
Stable neutral atoms form. Now the
Universe is transparent to radiation. Matter begins to
dominate over radiation
Notation: n - neutron, p - proton, e- - electron, e+ - positron, ν - neutrino, ν– -
antineutrino, D - deuterium, H - hydrogen, He - helium.
* Yu.E. PENIONZHKEVICH, Nuclear astrophysics, Soros Educational Journal, 1998, No. 10, pp. 68–76.
Temperature 3*10^9 ÷ 3*10^8 K, time – up to 35 minutes from the moment of the Big Bang,
primary synthesis of helium:
n + p → D + γ
D + n → 3H + γ
D + p → 3He + γ
D + D → 3H + p,
D + D → 3He + n
3H + p → 4He + γ
3He + n → 4He + γ
The result is 4He / (H + 4He) ~ 22-28% (by mass)
In stars at temperatures below 2*10^7 K, the proton-proton cycle of helium synthesis:
p + p → D + e+ + ν
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D + p → 3He + γ
3He + 3He → 4He + 2 p
3He + 4He → 7Be + γ
7Be + e– → 7Li + ν
7Li + p → 2 4He
overall process 4 1H → 4He + 26.7 MeV
(1 eV = 96.48 kJ/mol; 1 MeV = 96480000 kJ/mol)
The catalytic CNO cycle of helium synthesis:
12C + p → 13N + γ
13N → 13C + e+ + ν
13C + p → 14N + γ
14N + p → 15O + γ
15O → 15N + e+ + ν
15N + p → 12C + 4He
At temperatures above 10^8 K, helium "burning" (12C* is an excited carbon nucleus):
3 4He → 12C* + 7.274 MeV
energy of 12C*: 7.654 MeV
4He + 4He → 8Be*
8Be* + 4He → 12C*
12C + 4He → 16O + γ
At temperatures above 5*10^8 K, "burning" of carbon, oxygen, neon and silicon:
12C + 12C → 20Ne + 4He + 4.62 MeV
12C + 12C → 23Na + p + 2.24 MeV
12C + 12C → 24Mg + γ - 2.60 MeV
16O + 16O → 28Si + 4He + 9.59 MeV
16O + 16O → 31P + p + 7.68 MeV
16O + 16O → 31Si + n + 1.45 MeV
16O + 16O → 30Si + 2 p + 0.39 MeV
16O + 16O → 24Mg + 2 4He - 0.39 MeV
16O + 16O → 27Al + 4He + p – 1.99 MeV
Neon burning is characterized by a short stage and consists in
the photodisintegration of 20Ne under the action of high-energy γ-quanta, with the removal of an α-
particle. The liberated α-particles interact with neon and other nuclei
until the supply of neon is exhausted.
28Si + 4He → 32S + γ
32S + 4He → 36Ar + γ
Unsolved problems:
1) What is the mass ratio of carbon to oxygen after the helium flash (this
ratio is extremely important for the further evolution of massive stars)?
2) Where exactly does the r-process (from English rapid) of rapid
neutron capture take place?
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3) Which nuclides due to proton processes are born in the various episodes of
nucleosynthesis?
4) What is the relative contribution of core-collapse supernovae, on the one hand,
and those produced by a CO explosion, on the other, to the formation of iron and other heavy
elements?
(Krugosvet encyclopedia http://www.krugosvet.ru/articles/20/1002099/1002099a1.htm)
The main paradoxes of the existence of planet Earth
To this day there is no scientific theory explaining why precisely this set of chemical elements
appeared in the Earth's crust. Science cannot explain the reasons
for the emergence of precisely the kind of material world that surrounds us. Here are
some examples of the limits of scientific knowledge about the origin of matter:
1. Because of the negligible difference in the masses of the proton (1.00797
a.m.u.) and the neutron (1.00867 a.m.u.), the proton (the nucleus of the hydrogen atom) turned out to be a stable particle, while the neutron is
unstable (outside the atomic nucleus), with a half-life of 11.7 min (702 seconds) [21].
The neutron decays into a proton p+, an electron e- and an antineutrino ν:
n0 = p+ + e- + ν–
With even the slightest decrease in the mass difference between proton and neutron, the proton would
become unstable and the whole picture of the world would change. The difference in the masses of the proton and the electron, a factor of 1870, also has no scientific
explanation [22].
2. According to the "Big Bang" theory, at the stage of primary nuclear synthesis the
process stopped at helium nuclei. The probable composition of the early Universe: 22-28%
helium, the rest hydrogen (baryonic matter). At the same time baryonic matter accounted for
a negligible part of the mass, which was mostly provided by photons (69%) and neutrinos (31%)
[23]. Further nucleosynthesis was impossible – the excess energy of the nuclei being formed
caused them to decay. For example, the excited beryllium-8 nucleus, which is formed
in the reaction
4He + 4He → 8Be*, is able to live on average only 10^-17 s.
This explains the so-called "mass gap" – the absence of nuclei with masses 5 and 8, and
the low relative abundance in the Earth's crust of lithium-7, beryllium-9 and boron-11, which were
formed later as fragments of the synthesis of heavy elements. The content of beryllium in the crust
(2.6*10^-4 g per ton) is approximately equal to the content of uranium (2.4*10^-4 g per ton)
[24].
The situation was "saved" by carbon-12. It turned out that its nucleus can have
an excited state with an energy of 7.654 MeV, which is 0.38 MeV more than the total
energy released when three alpha particles combine. A possible reaction
for the formation of carbon-12 would be the fusion of three helium-4 nuclei (α-particles) into
excited carbon-12:
4He + 4He + 4He → 12C*
This, however, is a very improbable reaction, since three nuclei take part in it
simultaneously. Other processes were then proposed. For example, during the short
lifetime of the excited beryllium-8 nucleus it is quite possible for it to collide (in only
10^-21 s) with one more α-particle:
8Be* + 4He → 12C*
For the excited carbon-12 nucleus not to decay, there must exist for it an
"allowed" resonance energy level corresponding to the sum of the energies of
all the reacting particles (on the left). This level, necessary for building
our material Universe, turned out to really exist. As a result, in
secondary nucleosynthesis (in newly formed stars) the synthesis of
carbon (at 100 million °C) and of heavier elements became possible. This possibility was predicted
theoretically by the English astrophysicist F. Hoyle and proved experimentally by W. Fowler
(Nobel Prize 1983). Hoyle was greatly impressed by his own
prediction and later admitted [25]: "Nothing has shaken my atheism more than
this discovery."
However, in stars equilibrium synthesis is possible only for elements up to and including iron
(at 4 billion °C), since the formation of heavier nuclei already requires
an expenditure of energy [26].
3. Heavy and especially radioactive elements (uranium) could only have been produced
by rapid neutron capture in extremely powerful neutron fluxes,
possible in the explosions of supernovae [27]. The possible contribution of supernova explosions
to nucleosynthesis is confirmed by the discovery of meteorites with an unusual isotopic
composition of elements. The isotopic anomalies in the composition of some meteorites have allowed
astrophysicists to assert that the Solar System began to form soon after a
nearby supernova explosion [28].
To this day there is no theory that satisfactorily explains why the
Solar System contains both Jupiter-type planets, consisting of light
elements, and the Earth, which contains quite a lot of elements with atomic masses
above 60.
An analysis of modern cosmology leads to the thought that there are too many
"happy coincidences" that allowed our planet and
man on it to arise. Instead of an explanation, scientists proposed the "anthropic principle" (from the
Greek anthropos – man). It is known in two formulations. According to the "weak"
anthropic principle, there is an infinite number of unconnected universes with
an infinite variety of physical constants. Among them our
Universe arose by chance, one in which the ratio of the fundamental parameters allowed
life and intelligence, i.e. an "observer", to appear. The German physicist Peter Hegele writes [29]:
"The weak anthropic principle (WAP in the English-language literature) is a reminder
that in developing theories the observer must be taken into account from the outset. Every
cosmogonic theory must be compatible with the presence of an observer. At least
since the creation of quantum theory it has been clear to scientists that phenomena must
be considered with account taken of the influence of the observer on them (the process of measurement).
As applied to cosmic theories, this means that one should not create theories
that do not permit the existence of an observer at all. WAP thus plays the role of a
"filter" for possible theories.
The decisive discovery is that, according to today's ideas about the
development of our Cosmos, this filter lets almost nothing through! If one considers the
set of conceivable cosmoses, characterized by different laws of nature,
different constants and diverse boundary and initial conditions, then
the share of those in which carbon-based life could arise is vanishingly
small. Examples of fine-tuned coincidences show within how narrow limits of the values of the
constants life is possible at all. ...
If such precise coincidences were necessary for the emergence of life,
perhaps life is not, after all, an insignificant product of chance, but is
intended and planned? Perhaps a "design", a well-thought-out plan and deliberate intentions are hidden in the observed development?
Or a designer?"
The "strong" anthropic principle asserts that our Universe must be
just such as to allow man
("the observer") to arise in it at some stage of evolution [30]. It is not discussed for whom and why our
Universe "must" be so.
The observed fine-tuned coincidences of the physical constants of our Universe are
usually explained within at least four approaches:
1. A connection between the fine-tuned coincidences and the emergence of life
is categorically denied.
2. The fine-tuned coincidence – in contrast to the arguments set out above
– is regarded as a fact that happened of necessity and requires no further
explanation.
3. The fine-tuned coincidences are merely evidence of
regularities and interconnections not yet discovered.
4. The fine-tuned coincidences are regarded as a chance coincidence and,
consequently, require no further explanation.
Some interpret the fine-tuned coincidences agnostically: a deeper
justification is absent, and perhaps it does not exist at all. The random is not
subject to any meaningful interconnections. Should we come to terms with this?
Are "chance and necessity" really enough to explain the world?
A simple theistic interpretation is also possible: a brilliant designer, God the
Creator, built our Universe according to his plans in such a way that life could
arise and persist in it. The laws of nature and the constants have as their purpose
the creation of the conditions necessary for life. It turns out that modern natural
sciences confirm the Old Testament:
"For thus saith the LORD that created the heavens; God himself that formed the earth
and made it; he hath established it; he created it not in vain, he formed it to be
inhabited: I am the LORD; and there is none else" (Isaiah 45:18)
Optical asymmetry of biologically active molecules.
In most school organic chemistry textbooks optical isomerism
is not considered, although it constitutes the main difference between the products of reactions in living
cells and their synthetic analogues. It is known that living organisms contain
many optically active molecules, and in the form of only one of the optical
isomers. Ordinary organic syntheses always yield a mixture of optical
isomers (a racemate). The first truly asymmetric synthesis, leading to the
preferential production of one of the optical isomers, was carried out in
1934 using polarized light [31]. Even today, however, for the
production of foods, vitamins and many drugs, biological methods are used
exclusively, since synthetic chemistry cannot
compete with the living cell in asymmetric synthesis. It remains unclear at
what stage of the chemical evolution of matter, and how, the optical asymmetry
of organic molecules arose.
One of the recently proposed hypotheses is as follows:
Studying the polymerization of formaldehyde at ultralow temperatures initiated by high-energy
radiation, Academician of the Russian Academy of Sciences
V.I.Goldanskii gave an explanation of one of the main riddles of the origin of life.
V.I.Goldanskii suggested that in the conditions of ultracold interstellar
gas permeated by cosmic radiation, the selective synthesis of
optically active molecules is possible. Indeed, molecules of
amino acids have been detected in space. At ultralow temperatures the selectivity of chemical reactions is
very high; even a slight difference in the energies of the possible products leads
to the preferential formation of the more favorable reaction product. If we
assume that quantum effects (tunneling) are important at ultralow temperatures,
then the selectivity of the processes increases even more.
Optical isomers are indistinguishable in ordinary reactions. However, in solid
ultracold crystals of interstellar ice, under the influence of radiation and
magnetic fields, a difference that is "invisible" at 300 K appears – and isomers of only one orientation
are predominantly formed. The emergence of an uneven
12
distribution of optical isomers may eventually lead to a "biological
Big Bang", when polymers made of optical isomers of one orientation
turn out to be more capable of "self-assembly" – a process that occurs in every living cell
Early definitions:
Substance
L.Pauling: [33, p.69] "An elementary substance is a
substance that consists of atoms of only one kind. A compound is a substance
that consists of atoms of two or more kinds."
Atom
D.I.Mendeleev [34, p.155] proposes, instead of atoms (Greek), the concept of
individuals (Latin) – indivisible only in a certain sense, but divisible in principle.
[p.156] "The atomic conception of matter was born in antiquity and until
recently (1895) has been struggling with the dynamic conception, which regards
matter merely as a manifestation of forces."
"Modern atomism, in my opinion, should be regarded first of all as
a device or method convenient for dealing with the ponderable matter of nature."
"When Dalton (1804) discovered the law of multiple proportions, he declared in favor of
the atomic doctrine, because with it the understanding of the law of multiple proportions becomes
very simple. If the divisibility of every simple body has a limit, namely the atom,
then the atoms of simple bodies are the ultimate limits of all divisibility, different from one another
by nature, and the formation of a compound body from simple ones must consist in
the union of several dissimilar atoms into one whole or into a system of atoms,
now called a particle or molecule."
[p.158] "Thus the atomic doctrine, which admits only a finite mechanical
divisibility, must, at least until now, be accepted only as a device,
similar to the device a mathematician uses when he divides a continuous curved
line into a multitude of straight lines. Atoms offer simplicity of representation,
but there is no necessity to resort to them. What is necessary and certain is one notion, that of the
individuality of the parts of matter, represented by the chemical elements."
[p.229] "Atoms are the smallest quantities, or indivisible chemical masses,
of the elements, forming the particles of simple and compound bodies."
At the beginning of the 20th century: "Atoms are imaginary particles of which
bodies consist." The chief anti-atomist was Wilhelm Ostwald (1853-1932), Nobel Prize
1909 (for his research on catalysis).
L.Pauling: [p.24] "Atoms are particles that
are preserved in chemical reactions."
[p.70] "An element is a kind of substance represented by atoms of a definite kind, namely
atoms with the same atomic number."
Molecule
D.I.Mendeleev [p.228] "A particle, or chemical particle, or molecule,
is to be considered the quantity of a substance that enters into chemical interaction with
other particles and that occupies in the gaseous state the same volume as is
occupied by two parts by weight of hydrogen."
L.Pauling: [p.34] "The crystals of many substances contain discrete groups of
atoms; such groups of atoms are called molecules."
Valence
L.Pauling: [p.159] "Some elements have a quite definite
ability to form compounds, or possess a definite valence (from the
Latin valentia – strength or capacity), which determines the number of other atoms with
which an atom of the given element can combine."
Chemical reaction
L.Pauling: [p.74] "The process of conversion of some substances into other substances by
the redistribution of atoms is a chemical reaction."
Supplement 2 to Lecture 2
The Origin of Stars and Planets
http://www.astrolab.ru/cgi-bin/ ASTROLAB.ru
How Are Stars Born?
What, then, are the theoretical justifications for the process by which rarefied interstellar
matter condenses into stars under the action of gravity?
It turns out that I.Newton formulated them quite fully long before the first observational
indications of the gravitational instability of the interstellar
medium appeared. Five years after I.Newton published his law of gravitation, his
friend the Reverend Richard Bentley, who was then head of Trinity College
in Cambridge, asked Newton in a letter whether the force of
gravity he had described might be the cause of the formation of stars (it seems to us that such a precise formulation of
the problem makes R.Bentley a co-author of the principle of
gravitational instability stated by Newton).
In his reply to Bentley of 10 December 1692, Newton wrote: "It seems to me that if all the
matter of our Sun and planets and all the matter of the Universe were evenly
scattered throughout the heavens, and if every particle had an innate gravity
toward all the rest, and if, finally, the space in which this
matter was scattered were finite, the matter on the outside of this space, by virtue of
that gravity, would be drawn toward all the matter on the inside and as a result would fall
into the middle of the whole space and form there one great spherical
mass. But if the matter were evenly distributed throughout an infinite
space, it could never unite into one mass, but part of it
would condense here and part there, forming an infinite number of great masses,
scattered at great distances from one another throughout all that infinite
space. And thus might the Sun and the fixed stars be formed,
supposing the matter to be of a lucid nature."
Thus the great physicist for the first time formulated the principle of gravitational
instability of homogeneous matter and, in essence, created the first scientific
concept of the origin of planets and stars. Let us note once more the stimulating role of the
question asked by R.Bentley. In this connection one may recall, if only as a
historical curiosity, that 17 years after the exchange of letters between Newton and
Bentley, another "servant of the cult", Bishop George Berkeley, used Newton's authority and
statements to justify his purely idealistic views of the world.
"My doctrine," he wrote, "fits perfectly with the idea of creation: I believe that neither
matter, nor the stars, nor the Sun, etc. existed before." After Newton such
views were perceived as quite natural.
Having created the steam engine and theoretical thermodynamics, the scientists of the 19th century understood that the
behavior of rarefied matter depends not only on gravity but also on the
thermal energy stored in it. The exact solution of the problem of gravitational
instability was obtained in 1902 by the English theorist James Hopwood Jeans (1877-
1946). Studying the propagation of sound waves in a gas with allowance for gravitational forces, he
showed that there exists a critical (now we say Jeans) value of the
sound wavelength (hJ) that separates the spheres of influence of gravity and gas
pressure.
If a condensation with a characteristic size h < hJ is created in a gas, then the force of gravity
will overcome the gas pressure, and the condensation will no longer be able to expand, but will continue
to contract under its own weight.
To understand why the behavior of short-wavelength density perturbations is governed by
the force of gas pressure, and that of long-wavelength ones by gravity, let us consider their influence on
matter as if separately. If there were no gas pressure, then under the
action of gravity all the matter of the cloud would gather at its center in the
free-fall time (t_fall), which depends only on the average spatial
density of the gas, and therefore has the same value for density perturbations of
any characteristic size.
On the other hand, in the absence of gravity the force of gas pressure would make the
cloud expand. In the free state a gas expands at a speed close to the
speed of sound, i.e. close to the average speed of thermal motion of the molecules. Thus the
characteristic expansion time of a given gas volume (t_exp) can be estimated by
dividing its size by the speed of sound in the gas. And since the speed of sound depends
only on the temperature and chemical composition of the gas, the expansion time is directly
proportional to the size of the cloud.
Consequently, in small density perturbations (t_fall > t_exp) the gas
pressure will always have time to redistribute the matter in such a way as to
prevent further contraction. Conversely, large density perturbations
(t_fall < t_exp), once they arise by chance, can no longer expand again: they
simply do not have enough time for this, since gravity will act faster than the force of gas
pressure. This process is called gravitational (or Jeans)
instability.
The reasoning above can be translated from the language of characteristic times into the language of
forces, which makes it possible to determine more precisely the values of the critical
wavelength (hJ) and mass (MJ) of a gravitationally unstable density perturbation. This was
done by J.Jeans at the beginning of the 20th century, who investigated the process of gravitational
instability using exact equations for the propagation of sound waves in a gas.
But in these equations, besides the force of gas pressure, the force of the gas's
own gravity appeared for the first time. Before Jeans nobody took this "small correction" into
account. Indeed, in laboratory conditions it is negligible, but on the scale of a
galaxy this force is quite real, and on an equal footing with the pressure of particles and of the magnetic
field it governs the motion of enormous masses of interstellar gas.
240 years after Newton's letter to Bentley, Jeans wrote in his book "Stars in Their Courses"
(Russian translation "The Motion of Worlds", Moscow, 1933): "Suppose that at the
beginning of time all space was filled with gas... Then it can be proved that the gas
would not have remained uniformly distributed in space, but would immediately have begun to
gather into spheres. We can calculate how much gas will be required to form
each sphere."
16
Indeed, unlike Newton, Jeans was able to calculate this. Thus, from
Newton's hypothesis to Jeans's theory it took the construction of all of classical
physics, which occupied two and a half centuries. Taking into account only gas pressure and
gravity, Jeans obtained simple formulas for calculating the critical
parameters of gravitationally unstable density perturbations. As these
formulas show, both the minimum size (hJ) and the minimum mass (MJ) of such perturbations
increase with increasing gas temperature and decrease with increasing gas density.
These formulas were obtained back at the beginning of the century, when almost no
information was available about the state of the interstellar medium, above all about the diversity of the physical
conditions and processes in it. Probably for this reason Jeans himself rather lightly
remarked: "...it is clear to us why all stars have a very similar weight; it is because
they were all formed by the same process. They are, perhaps, like factory
products made by the same machine." As is now becoming clear, stars are in
reality very diverse: the range of their masses spans at least three
orders of magnitude, and there are noticeable differences in their chemical composition, in the
strength of the magnetic field, and in the rotation speed.
And yet it is only now that we have fully felt the power of Jeans's formulas. If we take as
typical sites of star formation small-scale condensations in
molecular clouds, where the temperature is T=(5-20) K and the particle concentration n=(104 –
106) cm-3, and use these values to calculate MJ according to Jeans, we obtain
MJ=(0.03-3) M☉. An excellent result, if we recall that in this simple formula it
proved possible to "bypass" such important physical factors as the elasticity of the interstellar
magnetic field, the external gas pressure, the gravity of the stars already present in the gas and around
it, the rotation of the gas cloud, etc.
http://newplanet.nm.ru/worlds.htm
IMMANUEL VELIKOVSKY WORLDS IN COLLISION
Immanuel Velikovsky WORLDS IN COLLISION Translated from the English
The Origin of the Planetary System
All theories of the origin of the planetary system and of the driving forces that make the
"seven planets" revolve around the Sun proceed from the law of universal gravitation and
Newton's celestial mechanics. The Sun attracts the planets to itself. And if the force of its
gravity were not balanced by another, opposite one, all the planets would fall
onto the Sun. But each of them, by virtue of inertia, must move in the direction
opposite to the Sun, and thus an orbit is created. In the same way a
satellite, or moon, is subject to the same influence – one force drives it away from
the planet, but gravity bends the path that the moon would follow in
the absence of mutual attraction; and here too the orbit is created by the action of the same two forces.
Inertia, or the persistence of motion, inherent in planets and satellites, was
proclaimed by Newton, but he did not explain when and how the initial
push was given.
The theory of the planetary system that dominated during the 19th century was
proposed by the theologian Swedenborg and the philosopher Kant. Laplace gave it a scientific
basis, though without mathematical calculations. In brief, it is as follows.
Hundreds of millions of years ago the Sun was an enormous
nebula, close in shape to a disk. This disk extended out to the orbits of the present
outer planets and rotated about its center. Under contraction, or
self-gravitation, the sphere of the Sun formed at the center. As the nebula rotated
17
centrifugal forces arose; the matter that had gathered closer to the periphery resisted
being pulled toward the center and therefore broke off in rings, which then rolled up into
spheres. These were the planets in the process of their formation. In other words, as a result of the
contraction of the rotating sun, matter was torn off, and from the flesh of the solar matter
the planets arose. The plane in which the planets revolve is the plane of the
Sun's equator.
Today the nebular theory, or nebular hypothesis, is recognized as
unsatisfactory. Three objections are raised against it. First, the rotation speed of
the Sun about its axis at the time the planetary system appeared would have been
not so great as to allow part of the matter to break away; but even if it had broken away,
this matter could not have clumped together into planetary spheres. Second, Laplace's theory does not
explain why the planets have a greater angular velocity of daily axial
rotation and of yearly orbital revolution than the Sun could have imparted to them. Third,
it is unclear what made some satellites rotate in the opposite
direction, contrary to the rotation of most of the planets of the Solar System.
"It can be stated with full certainty that, regardless of the composition of the
original sun, the planetary system could not have arisen merely as a result of its
rotation. If the sun rotating in space proved incapable on its own of
producing a family of planets and satellites, we have to admit the presence of some second
body and help from it. And this leads us to the tidal theory."
The tidal theory, known at an earlier stage as the planetesimal theory,
assumes that some star passed close to the Sun. A gigantic
prominence was torn out of the Sun, rushing after the passing star.
However, it remained within the Solar System and served as the building
material for the planets. According to the planetesimal theory, the mass torn from the Sun
broke up into parts that gradually solidified; some were flung beyond the
Solar System, others fell back onto the Sun, and the rest, obeying the force of
gravity, continued to revolve around the parent luminary. Moving along
elongated orbits, they joined together in chance collisions, gradually
rounding their orbits, and finally turned into planets, some of which
acquired satellites of their own.
The tidal theory does not allow for the possibility that the matter torn from the Sun
first dispersed and only then came together again; the ejected matter,
breaking into pieces, fairly quickly passes from the gaseous state into the liquid and
solid. In support of the theory the following consideration was also adduced: with such an ejection
and breakup of matter into separate "drops", the largest of them are most likely to
form in the middle part, and the smallest "drops" at the beginning (near the Sun) and at the
end (at the edge of the Solar System). Indeed, Mercury, the planet nearest to the
Sun, is the smallest. Venus is somewhat bigger, the Earth slightly bigger than Venus. Jupiter is
three hundred and twenty times greater (in mass) than the Earth. Saturn is a little smaller than Jupiter.
Uranus and Neptune, though large planets, are no match for Jupiter and Saturn. Pluto is as
small as Mercury.
The first difficulty of the tidal theory arises in the matter that seems to be
considered its strongest point – the mass of the planets. Between Jupiter and the Earth
revolves the small planet Mars, which has only one tenth of the volume of the Earth, whereas
according to the given scheme a planet ten to
fifteen times larger should follow the Earth. Again, Neptune is larger, not smaller, than Uranus.
Another difficulty is the rare, as is generally believed, occurrence of an encounter of two stars.
One of the authors of the tidal theory estimated the probability of such an encounter as follows:
"The presumed chances of a given star forming its own planetary system
may arise only once in the course of 5,000,000,000,000,000,000 years." But since the period of
a star's existence is much shorter, "only one in 100,000
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stars has a chance, during its lifetime, of forming a planetary
system." In a system of galaxies numbering one hundred million stars, planetary
systems "are formed with a presumed periodicity of one system per five
billion years... Our own system, whose approximate age is two
billion years, is perhaps one of the youngest in the whole galactic system of stars."
Both the nebular theory and the tidal theory consider the planets to be derivatives
of the Sun, and their satellites to be derivatives of the planets.
The question of the origin of the Moon may prove very awkward for the tidal theory.
Though smaller than the Earth, the Moon nevertheless passed through the process of cooling
and contraction earlier, and its volcanoes lost their activity long ago. It is known that the Moon has a lower
specific gravity than the Earth. It is assumed that the Moon arose from the upper layers of the terrestrial
globe, rich in light silicon, while the Earth's core, the main part of the planetary
matter, consists of heavy metals, chiefly iron. It follows from this that the
birth of the Moon did not coincide in time with the formation of the Earth. Having arisen from
matter ejected by the Sun, the Earth must have gone through a process of leveling,
in which the heavy metals settle into the core and the silicon gathers in the upper layers,
and this process would have had to be completed by the time the Moon was torn away from
the Earth by a repeated strong tide. And this would mean two successive tides
in a system where the possibility of even one is considered extremely rare. If
the passage of one star near another, among one hundred million stars, is admitted
once in five billion years, then two such events for the same
star appear entirely improbable. Therefore, in the absence of a
satisfactory explanation, it is accepted that the satellites were torn away from
their planets by the attraction of the Sun at the moment of their first perihelion, when the planets, still
revolving in elongated orbits, came close to the Sun.
The revolution of satellites around planets also contradicts the existing
cosmological theories. Laplace built his theory of the origin of the Solar System
on the assumption that all planets and satellites rotate in the same
direction. He asserted that the rotation of the Sun about its axis, as well as the
orbital revolutions and axial rotations of the six planets, the Moon, the satellites and the rings of
Saturn taken together, make up forty-three motions, all in the same
direction. "Having analyzed all the possible variants, we come to the conclusion: out of more than
four thousand billion chances only one remains that such an order is not merely
accidental; the probability here is higher than the reality of historical events, which
hardly anyone would doubt." Laplace concluded that the original and common motion was
imparted to the planets and
продолжение следует...
Часть 1 2. Basic Concepts of Chemistry: Chemical Evolution of Matter
Часть 2 - 2. Basic Concepts of Chemistry: Chemical Evolution of Matter
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