Chemical atom

“ Further, an atom of any kind or sort, retains its identity and remains the same throughout all chemical combinations or physical changes which it may undergo. By spectroscopic analysis, it has been ascertained, for example, that hydrogen exists in the sun and stars, and the conclusion is arrived at in connection therewith, that an atom of hydrogen in any sun or star is the same as an atom of hydrogen in our atmosphere, or in any of the compounds, as water, in which it is found. ”

“ Any further division destroys the entity of the compound, and results in the decomposition of the salt into the atoms of its elements. Hence a simple molecule is the smallest portion of any chemical compound that is not susceptible of subdivision without destroying its entity, or, in other words, the smallest number of atoms that can cohere to form a compound constitute the molecule of that compound. An atom is designated as the ultimate particle of any elementary body, and is not susceptible of any further division within the range of human analysis. ”

“ While, however, an appreciation of this ceaseless activity of the atom is essential to a proper understanding of its chemical efficiency, yet from another point of view the "saturated" molecule—that is, the molecule whose atoms have their valency all satisfied—may be thought of as a relatively fixed or stable organism. Even though it may presently be torn down, it is for the time being a completed structure; and a consideration of the valency of its atoms gives the best clew that has hitherto been obtainable as to the character of its architecture. ”

“ When the chemical and physical properties of the elements were known to be periodic functions of their atomic weights, the idea of a common origin and common substance became much more credible. Differences in atomic weight and differences in properties alike might reasonably be explained by the differences in the amount of the primordial substance present in the various atoms; an atom of oxygen being supposed to be composed of sixteen times as much stuff as the atom of hydrogen, but to be made of the same ultimate material. ”

“ Since the electron can be got from all the chemical elements, we may conclude that electrons are a constituent of all atoms. We have thus made the first step towards a knowledge of the structure of the atom and towards the goal towards which since the time of Prout many chemists have been striving, the proof that the atoms of the chemical elements are all built up of simpler atoms—primordial atoms, as they have been called. ”

“ No less than five oxygen compounds with nitrogen are known, where with a given quantity of nitrogen the oxygen is combined in ratios of one, two, three, four and five.
These simple number relations can be explained very easily by the atomic theory, by assuming, first, that all atoms of the same element have the same weight; and second, that in a chemical combination between two elements the atoms combine to form an atomic group characteristic of the compound in question—a compound atom, as Dalton called it, or a molecule, as the atomic group is now called. ”

“ The beauty of science is due to the fact that the correct answers to our most interesting questions have turned out to be surprising by their simplicity.
In order to understand an atom one must consider the distribution of electrons around one nucleus. In order to understand a molecule one has to consider the distribution of electrons around two or more nuclei. The chemical behavior of an atom is the manner in which it interacts with other atoms, and that means the precise way in which the electrons rearrange themselves when two or more atoms approach each other. ”

“ Thus one of the Meta molecules of iron, containing seven atoms, is identical in appearance with a Hyper heptad, but the latter dissociates into seven atoms, the former into two triads and a single atom. Long-continued research into the detailed play of forces and their results is necessary ”

“ The word “atom” in chemistry signifies the least possible quantity of any natural substance known to us. Atoms are chemical equivalents. Their chemical indivisibility, on account of which they are called “atoms,” is a fact of experience; but they are absolutely divisible, owing to their physical composition; for we know by the balance that atoms of different substances contain different quantities of matter ”

“ As all the oxygen and hydrogen do not combine to make the drop of water, some remaining in mechanical union to give it an atmosphere, and about one-fourth of its bulk being gas, so the atom formed of the ether does not use all the ether in its chemical union, retaining some in mechanical union for its envelope or atmosphere. ”

“ Should the progress of science lead to a theory of the constitution of chemical atoms—important as such a knowledge might be for the general philosophy of matter—it would make but little alteration in chemistry itself. The chemical atoms will always remain the chemical unit; and for the specially chemical considerations we may always start from the constitution of atoms, and avail ourselves of the simplified expression thus obtained—that is to say, of the atomic hypothesis. ”

“ The study of the behavior of organo-metallic compounds in chemical reactions led to the conclusion that various metallic elements possess a definite capacity of saturation with regard to the number of atoms of other elements with which they can combine, and demonstrated this regularity of atom-fixing power in the case of zinc, tin, arsenic, and antimony. ”

“ We have seen too that the atoms of all the elements except hydrogen can acquire more than one unit of positive charge. The maximum number of such units seems to depend on the atomic weight of the atom, for mercury, the heaviest atom yet investigated, it Is as large as eight, for krypton four or five, for oxygen two, and so on. ”

“ He thus arrived at his dualistic theory of chemical compounds, which attained great prominence and prevailed for a long time in chemical theory. According to this idea, each compound was supposed to be made up of a positive and a 304negative atom or group of atoms. For example, the formulas for potassium nitrate, calcium carbonate, and sulphuric acid corresponded to K2O.N2O5, CaO.CO2 and H2O.SO3 where we now write KNO3, CaCO3 and H2SO4, and the theory was extended to embrace organic compounds also. ”

“ The study of the way in which atoms combine into molecules belongs to chemistry, and will not much concern us. We are concerned with the structure of atoms, the way in which electrons and nuclei come together to build up the various kinds of atoms. This study belongs to physics almost entirely. There are three methods by which most of our knowledge is obtained: the spectroscope, X-rays, and radio-activity. The hydrogen atom, which has a simple nucleus and only one electron, is studied by means of the spectroscope almost alone. ”

“ It is a fascinating guess that the electrons constitute the fundamental substratum of which all matter is composed. That a grouping of say 700 electrons, 350 positive and 350 negative, interleaved or interlocked in a state of violent motion so as to produce a stable configuration under the influence of their centrifugal inertia and their electric forces, constitutes an atom of hydrogen. That sixteen times as many, in another stable grouping, constitute an atom of oxygen. That some 16,000 of them go to form an atom of sodium; about 100,000 an atom of barium; and 160,000 an atom of radium. ”

“ The atoms of carbon and hydrogen, oxygen, nitrogen, which enter into a complex molecule, do not lose the powers originally inherent in them, when they unite to form that molecule, the properties of which express those forces of the whole aggregation which are not neutralized and balanced by one another. Each atom has given up something, in order that the atomic society, or molecule, may subsist. ”

“ We have reason to believe that there are in each molecule of ordinary protoplasm at least 450 atoms of carbon, 720 atoms of hydrogen, 116 of nitrogen, 6 of sulphur, and 140 of oxygen. Nerve-plasm is still more complex.
Recent discoveries have only increased the wonder and potentiality of the cortex. Each atom has proved to be a remarkable constellation of electrons, a colossal reservoir of energy. The atom of hydrogen contains about 1,000 electrons, the atom of carbon 12,000, the atom of nitrogen 14,000, the atom of oxygen 16,000, and the atom of sulphur 32,000. ”

“ It is not in the atom itself, unless it be in the size, as may not be improbable. The atoms combine in different numbers to make differently shaped molecules, and it is from this difference in the shape of the molecule that we get the difference between gold and silver, copper and tin, or oxygen and hydrogen. ”

“ In the inanimate realm these associations, composed of the atoms of the different substances, forming what are termed molecules, are generally composed of but few units. Thus carbonic-acid gas, as it is commonly called, is made up of an aggregation of molecules, each composed of one atom of carbon and two of oxygen ”

“ Thus an alkali, which has one electron in the outer ring, will combine readily with an element that comes just before an inert gas, and so has one less electron in the outer ring than it can hold. An element which has two electrons in the outer ring will combine with an element next but one before an inert gas, and so on. Two atoms of an alkali will combine with one atom of an element next but one before an inert gas. An inert gas, which has its outer ring already complete, will not combine with anything. ”

“ For pith-balls read atoms, and we have an explanation of the univalent atoms like those of chlorine and sodium which act as single poles; and this is confirmed by the fact that such atoms are never found isolated, but are always associated in a molecule with at least one other atom which forms the opposite pole of the molecular system. Bivalent or magnetic atoms, on the other hand, which have two poles, like those of mercury and zinc, may constitute a complete polar system and be found isolated, and form the class of molecules which consist of single atoms. ”

“ We can produce a system which is still simpler than the ordinary hydrogen atom, for we can extract the electron from the atom and get merely the positive charge left: these positively charged hydrogen atoms exist in large numbers in the positive rays. ”

“ How can an aggregation of atoms, having all their affinities satisfied, take any further part in chemical reactions? Seemingly such a molecule, whatever its physical properties, must be chemically inert, incapable of any atomic readjustments. And so in point of fact it is, so long as its component atoms cling to one another unremittingly. But this, it appears, is precisely what the atoms are little prone to do. It seems that they are fickle to the last degree in their individual attachments, and are as prone to break away from bondage as they are to enter into it. ”

“ Its affinities seem satisfied when it has two bonds. But, on the other hand, the atom of nitrogen is able to hold three atoms of hydrogen, and does so in the molecule of ammonium (NH3) ; while the carbon atom can hold four atoms of hydrogen or two atoms of oxygen.
Evidently, then, one atom is not always equivalent to another atom of a different kind in combining powers. ”

“ What is called the “atomic number” of an element is simply its place in this series. Thus hydrogen has the atomic number 1, and uranium has the atomic number 92. Helium is 2, lithium is 3, carbon 6, nitrogen 7, oxygen 8, and so on. Radium, which fits quite correctly into the series, is 88. The atomic number is much more important than the atomic weight; we shall find that it has a very simple interpretation in the structure of the atom. ”

“ The atomic weight is the one quality of
importance. The physical
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state, whether the element is in the solid, liquid or gaseous
state, is unimportant. And when we deal with molecules the
stopping power is simply proportional to the sum of the square
roots of the atomic weights of the atoms entering into the
molecule. This is the "additive law," and it obviously enables us
to calculate what the range in any substance of known chemical
composition and density will be, compared with the range in air. ”

“ We shall afterwards learn that the molecule of hydrogen contains two atoms, H2, but there are elements the molecules of which only contain one atom—for instance, mercury. Therefore, every reaction of gaseous hydrogen must be accompanied by the disruption of that bond which exists between the atoms forming a molecule. At the moment of evolution, however, it is supposed that free atoms exist, and in this condition, according to the hypothesis, act energetically. ”

“ Thus, in a mechanical mixture, we have groups of molecules of one substance mingled irregularly with groups of molecules of another substance, so that the atoms which are to combine are not in close proximity one to another, but, on the contrary, are, many of them, separated by wide intervals. In the chemical compound, however, the atoms are regularly distributed throughout the whole mass of the substance, and are, relatively to one another, in the most favourable position for combining. ”