| 单词 | atomic weight |
| 例句 | He believed also that water consisted of seven parts of oxygen to one of hydrogen, and so he gave oxygen an atomic weight of seven. A Short History of Nearly Everything 2003-05-06T00:00:00Z He knew, for instance, that hydrogen was the lightest element, so he gave it an atomic weight of one. A Short History of Nearly Everything 2003-05-06T00:00:00Z He wasn’t always terribly accurate–oxygen’s atomic weight is actually sixteen, not seven–but the principle was sound and formed the basis for all of modern chemistry and much of the rest of modern science. A Short History of Nearly Everything 2003-05-06T00:00:00Z The total number of neutrons and protons in an atom’s nucleus gives its atomic weight. "The Big Bang Theory" and real science, from Leonard's wedding vows to the "Time Machine" prop 2019-05-16T04:00:00Z It’s a little like being told that the human soul has a specific atomic weight. Museum of Food and Drink Takes a Look at Flavor 2015-10-20T04:00:00Z Each water molecule that is part of the cycle has a certain isotopic 'fingerprint,' or composition, which reflects small variations in the atomic weight of the oxygen and hydrogen atoms that comprise the molecule. Study links changes in global water cycle to higher temperatures 2023-11-02T04:00:00Z Rare earths refineries must contend with 17 metals, depending on a deposit's geology, each of which are nearly the same size and atomic weight, making separation complex. Insight: World battles to loosen China's grip on vital rare earths for clean energy transition 2023-08-02T04:00:00Z An average atomic weight cannot be determined for these elements because their radioisotopes may vary significantly in relative abundance, depending on the source, or may not even exist in nature. Chemistry 2019-02-14T00:00:00Z Generally, but not invariably, the elements of lower atomic weight are more abundant than those of higher atomic weight. Astronomy 2016-10-13T00:00:00Z Most of the carbon on Earth is carbon-12, which has an atomic weight of 12 and is not radioactive. Algebra and Trigonometry 2015-02-13T00:00:00Z The mole of an element is its atomic weight, while a mole of a compound is the sum of the atomic weights of its components, called the molecular weight. Anatomy and Physiology 2013-06-19T00:00:00Z In my chemistry class, we were told to memorize the periodic table and its atomic weights, and were graded accordingly. Project-based learning is how we teach critical thinking 2021-04-25T04:00:00Z Meticulous work by chemist Stephanie Horovitz, who purified and measured the atomic weights of lead chloride, revealed the first direct evidence for the existence of isotopes. Daily briefing: Oxford–AstraZeneca vaccine trial paused for safety reasons 2020-09-09T04:00:00Z The number after each element is its atomic weight, equal to the number of protons plus neutrons in its nucleus. Astronomy 2016-10-13T00:00:00Z This approach succeeds most of the time, when the issue is, say, the atomic weight of hydrogen. Coronavirus Responses Highlight How Humans Have Evolved to Dismiss Facts That Don't Fit Their Worldview 2020-06-26T04:00:00Z As atomic weights grew more accurate, more patterns emerged. The Histories Hidden in the Periodic Table 2019-12-27T05:00:00Z Cannizzaro produced a list of the atomic weights of the known elements, along with a rationale for the values, which he handed out as a pamphlet at a conference in Karlsruhe, Germany. Is It Time to Upend the Periodic Table? 2019-08-27T04:00:00Z Mendeleev was not the first to try to arrange elements by their increasing order of atomic weight. Can quantum ideas explain chemistry’s greatest icon? 2019-01-29T05:00:00Z Look at the chemical elements in Appendix K. Can you identify any relationship between the abundance of an element and its atomic weight? Astronomy 2016-10-13T00:00:00Z Positioning an element in the periodic table requires establishing its atomic weight and chemical properties. Celebrate the women behind the periodic table 2019-01-27T05:00:00Z Chemists soon noticed patterns when they grouped elements into sets of three by atomic weight. The Histories Hidden in the Periodic Table 2019-12-27T05:00:00Z There had been conflicting lists of atomic weights circulating at the time, and varying assumptions about what constituted an atom versus a molecule. Is It Time to Upend the Periodic Table? 2019-08-27T04:00:00Z In the early twentieth century, physicists including Charles Glover Barkla and Ernest Rutherford noticed that the central charge of an atom is roughly half of its atomic weight. Can quantum ideas explain chemistry’s greatest icon? 2019-01-29T05:00:00Z The parts are then separated, using magnets and flotation tanks to divide materials according to their atomic weights. The death and rebirth of Hyundai Trajet Y264 TKP 2015-04-17T04:00:00Z Working at the Radium Institute in Vienna, she showed that even a common element such as lead can have different atomic weights, depending on whether it stems from the radioactive decay of uranium or thorium3. Celebrate the women behind the periodic table 2019-01-27T05:00:00Z In the twentieth century, scientists realized that periodicity wasn’t determined by atomic weight; instead, what mattered was the number of protons that each atom contained in its nucleus. The Histories Hidden in the Periodic Table 2019-12-27T05:00:00Z Using moles and atomic weights, the math says there are 6.41 kilograms of hydrogen. Excerpts from The Mad Scientist's Handbook: The Human Recipe 2013-09-16T20:15:09.423Z The team's first two decays emitted alphas four times to produce a nucleus of dubnium with an atomic weight of 262 which then split apart by fission. Japanese Physicists Claim Clinching Observation of New Superheavy Element 2012-09-26T21:26:49Z The accepted atomic weight is accordingly double the density, i.e. approximately four times that of hydrogen. Encyclopaedia Britannica, 11th Edition, Volume 13, Slice 2 "Hearing" to "Helmond" 2012-04-25T02:00:53.567Z For example, radium behaves a lot like barium and has a heavier atomic weight, so it fits just below barium in the periodic table. Celebrate the women behind the periodic table 2019-01-27T05:00:00Z With low frequencies it seems that gases of great atomic weight excite more intense phosphorescence than those of smaller weight, as for instance, hydrogen. The inventions, researches and writings of Nikola Tesla With special reference to his work in polyphase currents and high potential lighting 2012-03-28T02:00:22.660Z He proceeds to give what has been quoted as his first table of atomic weights, but on p. Encyclopaedia Britannica, 11th Edition, Volume 7, Slice 9 "Dagupan" to "David" 2012-02-11T03:03:39.807Z Thallium is a rare metal, whose atomic weight is 204.2, its symbol being Tl. New, Old, and Forgotten Remedies: Papers by Many Writers 2012-02-05T03:00:10Z In order that the atomic theory should be fruitful of results, it was now necessary that the values of the atomic weights of many elements should be carefully determined. Heroes of Science Chemists 2011-12-09T03:00:21.047Z Determining atomic weights is difficult because it demands pure substances. Celebrate the women behind the periodic table 2019-01-27T05:00:00Z He had arranged the elements in the form of a table in the order of their atomic weights. Marvels of Scientific Invention An Interesting Account in Non-technical Language of the Invention of Guns, Torpedoes, Submarine Mines, Up-to-date Smelting, Freezing, Colour Photography, and many other recent Discoveries of Science 2011-11-19T03:00:24.517Z There are 17 rare earth metals on the periodic table, divided between “heavy” and “light” based on their atomic weight, the heavies being far more rare and expensive. Alaska’s Billion Dollar Mountain 2011-10-27T21:00:39Z I am engaged," he writes, "in a series of experiments intended to fix the atomic weights of a considerable number of bodies, by determining their density in the state of gas or vapor. Scientific Culture, and Other Essays Second Edition; with Additions 2011-09-17T02:00:31.747Z Let us consider what knowledge must be acquired before the value to be assigned to the atomic weight of an element can be found. Heroes of Science Chemists 2011-12-09T03:00:21.047Z Securing values for atomic weights was also crucial for working out radioactive decay series, and for telling apart new elements and unknown versions of existing ones — isotopes. Celebrate the women behind the periodic table 2019-01-27T05:00:00Z All of these had their atomic weights found, and fell into that new column in the periodic table. Marvels of Scientific Invention An Interesting Account in Non-technical Language of the Invention of Guns, Torpedoes, Submarine Mines, Up-to-date Smelting, Freezing, Colour Photography, and many other recent Discoveries of Science 2011-11-19T03:00:24.517Z But in the concept of gold color, lustre, malleability, hardness, solubility, fusibility, specific gravity, atomic weight, and all other qualities of gold, must be apprehended as clearly as possible. Anarchism 2011-07-12T02:00:35.053Z His determination of the atomic weight of oxygen by the synthesis of water, and of that of carbon by the synthesis of carbonic dioxide, are models of quantitative experimental work. Scientific Culture, and Other Essays Second Edition; with Additions 2011-09-17T02:00:31.747Z In the second part of the "New System" Dalton, guided by these rules, determined experimentally the atomic weights of a great many substances; but this was not the kind of work suited to Dalton's genius. Heroes of Science Chemists 2011-12-09T03:00:21.047Z It is easy, for example, to conceive that the heavy metals may lie somewhat deeper down within the Sun or star than those of low atomic weight. Are the Planets Inhabited? 2011-04-24T02:00:07.733Z Its atomic weight was found, and, wonderful to relate, it was such that argon fell into a new column to the left of Group 1, as had been anticipated. Marvels of Scientific Invention An Interesting Account in Non-technical Language of the Invention of Guns, Torpedoes, Submarine Mines, Up-to-date Smelting, Freezing, Colour Photography, and many other recent Discoveries of Science 2011-11-19T03:00:24.517Z The atomic weight of fluorine has been determined by the conversion of calcium, sodium and potassium fluorides into the corresponding sulphates. Encyclopaedia Britannica, 11th Edition, Volume 10, Slice 5 "Fleury, Claude" to "Foraker" 2011-04-03T02:00:20.883Z It was Dumas who first saw that these principles furnished an important means of verifying the molecular and atomic weights. Scientific Culture, and Other Essays Second Edition; with Additions 2011-09-17T02:00:31.747Z Hence it appears that Dalton's rules were too arbitrary, and that they were insufficient to determine with certainty the atomic weights of some of the elements. Heroes of Science Chemists 2011-12-09T03:00:21.047Z In other words, they form a series, not only as it regards their atomic weights, but also as it regards their own properties and the forms and properties of their compounds. Are the Planets Inhabited? 2011-04-24T02:00:07.733Z Three elements have been found since, and their atomic weights and properties are just such as to fill three of the blank spaces. Marvels of Scientific Invention An Interesting Account in Non-technical Language of the Invention of Guns, Torpedoes, Submarine Mines, Up-to-date Smelting, Freezing, Colour Photography, and many other recent Discoveries of Science 2011-11-19T03:00:24.517Z When multiplied by the valency it gives the atomic weight. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 7 "Equation" to "Ethics" 2011-02-27T03:00:31.973Z The initial letters of the Latin names are selected to represent the atoms of the seventy known elementary substances, and these letters stand for the definite atomic weights which are tabulated in all chemical text-books. Scientific Culture, and Other Essays Second Edition; with Additions 2011-09-17T02:00:31.747Z Now, we wish to determine the atomic weight of oxygen; that is, we wish to find how many times the oxygen atom is heavier than the atom of hydrogen. Heroes of Science Chemists 2011-12-09T03:00:21.047Z The other element, to which he gives the name Nebulium, will have an atomic weight of 2·1. Are the Planets Inhabited? 2011-04-24T02:00:07.733Z Like argon, it was found to be extremely inactive, and its atomic weight turned out to be such that it too fell into the "Zero Group." Marvels of Scientific Invention An Interesting Account in Non-technical Language of the Invention of Guns, Torpedoes, Submarine Mines, Up-to-date Smelting, Freezing, Colour Photography, and many other recent Discoveries of Science 2011-11-19T03:00:24.517Z Which of these ratios gives the true ratio of the atomic weights? Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z But as chemists now recognize, any attempt to establish an organizing pattern based on an element’s atomic weight will not succeed, because atomic weight is not the fundamental property that characterizes each of the elements. The Evolution of the Periodic System 2011-01-21T23:45:05.210Z Berzelius, we saw, greatly improved the methods whereby atomic weights could be determined, and he recognized the importance of physical generalizations as aids in finding the atomic weights of chemical substances. Heroes of Science Chemists 2011-12-09T03:00:21.047Z Back in high school, you opened your chemistry book and saw a table of standard atomic weights. Mass Migration: Chemists Revise Atomic Weights of 10 Elements 2011-01-04T16:18:28.497Z Previously, a given element’s official atomic weight was actually an average of this variation. Periodic Table Gets Some Flex 2010-12-22T16:35:00Z Are there disturbing causes also with atomic weights? Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z It included 63 known elements arranged according to increasing atomic weight; Mendeleev also left spaces for as yet undiscovered elements for which he predicted atomic weights. The Evolution of the Periodic System 2011-01-21T23:45:05.210Z Thus, when Dalton said the atomic weight of oxygen is 8, he meant that the atom of oxygen is eight times heavier than that of hydrogen. Heroes of Science Chemists 2011-12-09T03:00:21.047Z The interval doesn't reflect an uncertainty in measurement precision but rather a real variation of atomic weight from substance to substance. Mass Migration: Chemists Revise Atomic Weights of 10 Elements 2011-01-04T16:18:28.497Z Just as the weight listed on your driver’s license doesn’t necessarily reflect your actual poundage, the official atomic weights of the chemical elements are actually more like ballpark estimates than precise constants. Periodic Table Gets Some Flex 2010-12-22T16:35:00Z Another question regarding the values of atomic weights was raised very soon after their first establishment. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z He noticed that if the three members of a triad were ordered according to their atomic weights, the properties of the middle element fell in between those of the first and third elements. The Evolution of the Periodic System 2011-01-21T23:45:05.210Z Hence, before the atomic weight of an element can be determined, there must be found some method for determining the atomic weights of compounds of that element. Heroes of Science Chemists 2011-12-09T03:00:21.047Z Chemist Matt Hartings of American University in Washington, D.C., says that most chemists who don't think regularly about isotopic abundances or teach general chemistry at college would probably consider the atomic weights as constants. Mass Migration: Chemists Revise Atomic Weights of 10 Elements 2011-01-04T16:18:28.497Z The adjustments, published online December 12 in Pure and Applied Chemistry, are the first in an overhaul of the atomic weight of almost every element on the periodic table. Periodic Table Gets Some Flex 2010-12-22T16:35:00Z He therefore preferred to call the characteristic combining numbers of the elements not “atomic weights” but “chemical equivalents.” Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z In addition, Döbereiner showed that the atomic weight of the middle element is close to the average of the weights for the first and third members of the triad. The Evolution of the Periodic System 2011-01-21T23:45:05.210Z His analytical determinations were generally inaccurate; nevertheless, he clearly showed how the values of the atomic weights of elements ought to be established, and he obtained results sufficiently accurate to confirm his general theory. Heroes of Science Chemists 2011-12-09T03:00:21.047Z The atomic weight of arsenic has been determined by many different chemists. Encyclopaedia Britannica, 11th Edition, Volume 2, Slice 6 "Armour Plates" to "Arundel, Earls of" Instead of being described by a single fuzzy number, the atomic weights of oxygen, hydrogen, lithium, boron, carbon, nitrogen, silicon, sulfur, chlorine and thallium will now be expressed as intervals. Periodic Table Gets Some Flex 2010-12-22T16:35:00Z The law of the combining weights of the 256 atoms, or of the atomic weights, proved to hold good in every case in which it was tested. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z Döbereiner’s work encouraged others to search for correlations between the chemical properties of the elements and their atomic weights. The Evolution of the Periodic System 2011-01-21T23:45:05.210Z Berzelius at once accepted Mitscherlich's law, as an aid in his researches on atomic weights. Heroes of Science Chemists 2011-12-09T03:00:21.047Z The atomic weight of antimony has been determined by the analysis of the chloride, bromide and iodide. Encyclopaedia Britannica, 11th Edition, Volume 2, Slice 2 "Anjar" to "Apollo" They are similar to fats in chemical composition, except that, instead of being glycerides, they are esters of monohydric alcohols of high atomic weight. The Chemistry of Plant Life New determinations of the atomic weights were undertaken from all sides. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z He also corrected the atomic weights of some already known elements. The Evolution of the Periodic System 2011-01-21T23:45:05.210Z Hydrogen, rediscovered by Cavendish, 63; experimented on by Priestley, 66; its atomic weight decided by Dalton, 130; Graham considers it a metal, 238. Heroes of Science Chemists 2011-12-09T03:00:21.047Z The bulk of the lead obtained from radio-active minerals differs in atomic weight from ordinary lead and appears also to be different according to whether its source is a thorium or a uranium mineral. A Brief Account of Radio-activity Page 276 in the fourth group turned out to be a table of atomic weights. The Caves of Fear There is still another question regarding the numerical values of the atomic weights, namely: Are there relations between the numbers belonging to the several elements? Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z After this discovery, chemists turned to using atomic number as the fundamental ordering principle for the periodic table, instead of atomic weight. The Evolution of the Periodic System 2011-01-21T23:45:05.210Z The velocity of elementary ions is found to be a periodic function of the atomic weight, similar elements lying on corresponding portions of a curve drawn to express the relation between these two properties. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 8 "Conduction, Electric" Taking the atomic weight of gold into consideration, Rutherford calculated mathematically that this was about the number which should be driven backward. A Brief Account of Radio-activity Also that atomic weights are close integers, when hydrogen is one point zero zero eight. Jimsy and the Monsters To obtain a correct table of atomic weights the second question already mentioned, viz. how to select the correct value in the case of multiple proportions, had to be answered. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z It signifies nothing what interpretation we give to these numbers, whether we regarded them as atomic weights, or, declining the idea of atoms, consider them as the representatives of force. History of the Intellectual Development of Europe, Volume I (of 2) Revised Edition Such a curve much resembles that giving the relation between atomic weight and viscosity in solution. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 8 "Conduction, Electric" But he went further and calculated also the number which should be returned by aluminum, which has an atomic weight of only about one-seventh that of gold. A Brief Account of Radio-activity He called this proportion the “atom,” since it invariably enters compounds without division, and the weight of this atom is the atomic weight. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 1 "Châtelet" to "Chicago" Berzelius was constantly on the look-out for means to distinguish the true atomic weights from their multiples or sub-multiples, but he could not find an unmistakable test. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z This was published in 1805, and contains the atomic weight of twenty-one substances, some of which were probably added, or corrected, between the date of the first reading and the publication. A History of Science, Volume 5(of 5) Aspects Of Recent Science The velocity of the vapour of metals of low atomic weight was in general greater than that of the vapour of heavier metals. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 8 "Conduction, Electric" Comparing experiment with theory, the central charge in an atom corresponds to about one-half the atomic weight multiplied by the charge on an electron, or, as it is expressed, ½ Ae. A Brief Account of Radio-activity From the results obtained by Laurent and Gerhardt and their predecessors it immediately followed that, while an element could have but one atomic weight, it could have several equivalent weights. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 1 "Châtelet" to "Chicago" Then a startling discovery was made by the same method which Richter had tried in vain, by arranging all atomic weights in one series according to their numerical values. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z To properly understand the science of chemistry we must study the valence of the atom which determines the power of combination of the various elements, together with other niceties, such as atomic weight, density, etc. The Rosicrucian Mysteries An Elementary Exposition of Their Secret Teachings In the first, the different elements in their atomic form have different masses or atomic weights. The Machinery of the Universe Mechanical Conceptions of Physical Phenomena This gives the range of the alpha particles in such substances and is connected in a simple way with the atomic weight, that is, it is again fixed by the mass of the opposing atom. A Brief Account of Radio-activity The solution came about by arranging the elements in the order of their atomic weights, tempering the arrangement with the results deduced from the theory of valencies and experimental observations. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 1 "Châtelet" to "Chicago" The following table contains this periodic arrangement of the elements according to their atomic weight. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z There are precise ratios of atomic weights to be considered, of course, but it looks as if my friend is being extremely accurate in spite of his dazed condition. The Copper-Clad World It is possible to arrange the elements in the order of their atomic weights in columns which will show communities of property. The Machinery of the Universe Mechanical Conceptions of Physical Phenomena Its atomic weight has been determined by several careful investigators and is accepted as 226. A Brief Account of Radio-activity Chemists gradually tired of the notion of atomic weights on account of the uncertainty which surrounded them; and the suggestion made by W.H. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 1 "Châtelet" to "Chicago" In the first line one would expect that the steps in the values of the atomic weights should be regular, but it is not so. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z Gold and mercury have, in consequence of their great atomic weight, perhaps sunk away into the centre. Astronomy of To-day A Popular Introduction in Non-Technical Language Some of these have since been discovered, and their atomic weight and physical properties accord with those predicted. The Machinery of the Universe Mechanical Conceptions of Physical Phenomena The physical properties were investigated and, where possible, spectra were mapped and atomic weights determined. A Brief Account of Radio-activity The relation between the atomic Volume relations of solids. volumes and the atomic weights of the solid elements exhibits the periodicity which generally characterizes the elements. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 1 "Châtelet" to "Chicago" There are even cases when it is necessary to invert the order of the atomic weights to satisfy the chemical necessities. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z They represent absorption, not by new, but by scarce elements, especially, Father Cortie thinks, those with atomic weights of about 50. A Popular History of Astronomy During the Nineteenth Century Fourth Edition For equal weights of the simple bodies, the atomic weight multiplied by a number expressing the specific heat, gives a nearly uniform product. A System Of Logic, Ratiocinative And Inductive The number of recoil particles increases with the atomic weight of the metal. A Brief Account of Radio-activity This law—purely empirical in origin—was strengthened by Berzelius, who redetermined many specific heats, and applied the law to determine the true atomic weight from the equivalent weight. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 1 "Châtelet" to "Chicago" It may here be mentioned that the internationality of science has shown itself active also in the question of atomic weights. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z No. They know that there's no such thing as a gas with a lighter atomic weight than hydrogen. By Proxy We have, then, to consider the atom of any element as being composed of a vortex ring of various thickness, the thickness of the ring being an indication of its atomic weight. Aether and Gravitation This stopping power of an atom for an alpha particle is approximately proportional to the square root of its atomic weight. A Brief Account of Radio-activity Elements.—The following table gives the names, symbols and atomic weights of the perfectly characterized elements:— International Atomic Weights, 1910. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 1 "Châtelet" to "Chicago" Why nail the "power metal" down to an isotope of gold with an atomic weight of 197? Despoilers of the Golden Empire He found further that the change of the metallic contact resistance when acted upon by electric waves, is a function of the atomic weight. Sir Jagadis Chunder Bose His Life and Speeches The English degree is a survival of the time when the atomic weight of sodium was believed to be twenty-four instead of twenty-three, and, since the error on 76 per cent. The Handbook of Soap Manufacture In accepting this, the interpretation of function was both unmathematical and vague, and the order of the atomic weights was not strictly adhered to but unhesitatingly abandoned to force the group relationship. A Brief Account of Radio-activity Considerable uncertainty existed as to the atomic weights of these metals, the values obtained by Berzelius being doubtful. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 1 "Châtelet" to "Chicago" In his table of the elements grouped according to atomic weight, Mendelejef also acknowledges that the number seven controls what he calls the Law of periodical function. Reincarnation A Study in Human Evolution And since all the other metals I want worst are also very dense and of high atomic weight, they're probably mighty scarce here, too. Spacehounds of IPC The authors do not believe that the adoption of the oxygen standard introduces any real difficulties in making perfectly clear the methods by which atomic weights are calculated. An Elementary Study of Chemistry It was most helpful that, following the order of atomic weights, the majority of the elements fell naturally into their places. A Brief Account of Radio-activity In the development of the atomic theory and the deduction of the atomic weights of elements and the formulae of compounds, Dalton’s arbitrary rules failed to find complete acceptance. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 1 "Châtelet" to "Chicago" As the disintegration proceeds, the substances become of lighter and lighter atomic weights. The Outline of Science, Vol. 1 (of 4) A Plain Story Simply Told The atomic weight of caesium has been determined by the analysis of its chloride and bromide. Encyclopaedia Britannica, 11th Edition, Volume 4, Part 4 "Bulgaria" to "Calgary" Consequently the problem of deciding upon the relative atomic weights is not an easy one. An Elementary Study of Chemistry Influence of Positive Nucleus It is evident that the order of the elements is determined by something else than their atomic weights. A Brief Account of Radio-activity This fact finds a parallel in the atomic weights of these metals. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 1 "Châtelet" to "Chicago" Each descending element is of lighter atomic weight than its predecessor. The Outline of Science, Vol. 1 (of 4) A Plain Story Simply Told I don't get the two items after the atomic weight, though. Omnilingual Deduction of atomic weights from molecular weights and equivalents. An Elementary Study of Chemistry The atomic weight can usually be followed in fixing the atomic number, but where doubt exists the method just given can be resorted to. A Brief Account of Radio-activity C. Winkler decided the atomic weight of germanium by similar reasoning. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 1 "Châtelet" to "Chicago" There are classes and subclasses, orders or families, suborders, tribes, sub-tribes, genera, species, and varieties, just as in the world of plants and even, according to their atomic weight, among the elements. Evolution An Investigation and a Critique Well, the next information after the atomic weight ought to be the period and group numbers. Omnilingual Let us see how it is possible to decide which multiple of the equivalent really is the true atomic weight. An Elementary Study of Chemistry This would be the order according to the atomic weights. A Brief Account of Radio-activity Following this he put a few queries about specific gravity, atomic weight, and the like. The Young Pitcher And it is more probable that the mean atomic weight of a planet’s elements tends more to fix the position of equilibrium for each. Outlines of a Mechanical Theory of Storms Containing the True Law of Lunar Influence In consequence of the higher atomic weight of arsenic the results by this method are not so close as with the phosphide. A Text-book of Assaying: For the Use of Those Connected with Mines. If the element at the head of the family is a strong acid-forming element, this property is likely to diminish gradually, as we pass to the members of the family with higher atomic weights. An Elementary Study of Chemistry Atomic Weight Losses Each alpha particle emitted means a loss of 4 in the atomic weight. A Brief Account of Radio-activity Each letter represents a fixed quantity of the element for which it stands, viz., the atomic weight. Logic Deductive and Inductive The atomic weights are as 1 to 8, while their volumes are as 2 to 1; therefore, for equal spaces, the matter is as 1 to 16. Outlines of a Mechanical Theory of Storms Containing the True Law of Lunar Influence The number 75 is spoken of as the "combining weight," or, more frequently, as the "atomic weight" of arsenic. A Text-book of Assaying: For the Use of Those Connected with Mines. The metals of the other group—iridium, osmium, and platinum—have atomic weights near 200 and densities near 21. An Elementary Study of Chemistry Thus from uranium with an atomic weight of 238 to radium there is a loss of three alpha particles. A Brief Account of Radio-activity Nitrogen is a transparent colourless gas, atomic weight 14, specific gravity .9713, not readily combining, etc. Logic Deductive and Inductive As we now know, the scheme was built upon the false assumptions that the elements are immutable and that their atomic weights are invariable. Creative Chemistry Descriptive of Recent Achievements in the Chemical Industries Similarly 56 is the atomic weight of iron, and 32 the atomic weight of sulphur. A Text-book of Assaying: For the Use of Those Connected with Mines. It has already been explained that oxygen has been selected as the standard element for atomic weights, with a weight of 16. An Elementary Study of Chemistry Therefore, 12 must be subtracted from 238, leaving 226, which agrees closely with the atomic weight of radium as actually determined by the ordinary methods. A Brief Account of Radio-activity On the other hand, there is evidence arising from the atomic weight of lead which seems to involve some other parent than uranium. The Birth-Time of the World and Other Scientific Essays It appears then that the same chemical element may have different atomic weights according to its ancestry, while on the other hand different chemical elements may have the same atomic weight. Creative Chemistry Descriptive of Recent Achievements in the Chemical Industries The atomic weight of any particular element is the weight of its atom compared with the weight of an atom of hydrogen. A Text-book of Assaying: For the Use of Those Connected with Mines. These, then, are the steps necessary to establish the atomic weight of an element. An Elementary Study of Chemistry The other intermediate elements, whose formation is due to the loss of beta particles only, show no decrease in atomic weight. A Brief Account of Radio-activity The atomic weight of radium is well known, and uranium in its descent has to change to this element. The Birth-Time of the World and Other Scientific Essays Occult research ascertained the actual number in some cases by direct observation and then discovered the law governing the numbers in all cases, and the relation of these numbers to atomic weights. Occult Chemistry Clairvoyant Observations on the Chemical Elements The atom of sulphur, for instance, is 32 times as heavy as the atom of hydrogen, and the atomic weight of sulphur is 32. A Text-book of Assaying: For the Use of Those Connected with Mines. This law is not very accurate, but it is often possible by means of it to decide upon what multiple of the equivalent is the real atomic weight. An Elementary Study of Chemistry Lead the End Product From uranium to lead there is a loss of 8 alpha particles, or 32 units in atomic weight. A Brief Account of Radio-activity 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. The Birth-Time of the World and Other Scientific Essays This gave us a glimpse of a principle that might run all through the table of atomic weights. Occult Chemistry Clairvoyant Observations on the Chemical Elements The molecular weight is the sum of the atomic weights of the group. A Text-book of Assaying: For the Use of Those Connected with Mines. We see, therefore, that the atomic weight is twice the equivalent, or 55.9. An Elementary Study of Chemistry This would give for the final product an atomic weight of 206. A Brief Account of Radio-activity And so on for a whole sequence of transmutations, till finally a stable substance is formed, identical with ordinary lead in chemical and physical properties, but possessing a slightly lower atomic weight. The Birth-Time of the World and Other Scientific Essays Hydrogen is the lightest of the known elements, and is therefore taken as 1 in ordinary chemistry, and all atomic weights are multiples of this. Occult Chemistry Clairvoyant Observations on the Chemical Elements The molecule of pyrites contains two atoms of sulphur and one of iron: on referring to the table of atomic weights it will be seen that the atomic weights are—sulphur 32, and iron 56. A Text-book of Assaying: For the Use of Those Connected with Mines. As an example, let us suppose that the equivalent of nitrogen has been found to be 7.02 and that it is desired to obtain its atomic weight. An Elementary Study of Chemistry Several accurate determinations of lead coming from uranium minerals, which always carry this element and in an approximately definite ratio to the amount of uranium present, show atomic weights of 206.40; 206.36; and 206.54. A Brief Account of Radio-activity The stopping power of a substance is proportional to the square root of its atomic weight. The Birth-Time of the World and Other Scientific Essays The atomic weight of oxygen is commonly taken as 16. Occult Chemistry Clairvoyant Observations on the Chemical Elements A list of these symbols is given in the table of atomic weights. A Text-book of Assaying: For the Use of Those Connected with Mines. The smallest number so obtained will be approximately the atomic weight. An Elementary Study of Chemistry Determinations of the atomic weight of lead from thorite, a thorium mineral nearly free from uranium, gave 208.4. A Brief Account of Radio-activity If the nucleus were of the same density and atomic weight as the surrounding mica, there would be little effect. The Birth-Time of the World and Other Scientific Essays In this way, all through the table of atomic weights, hydrogen is taken as unity, without any attempt being made to estimate its absolute weight. Occult Chemistry Clairvoyant Observations on the Chemical Elements In some cases, the atomic weights of such allied bodies were nearly the same, or could be arranged in series, with like differences between the several terms. The Advance of Science in the Last Half-Century Dividing these figures by the respective atomic weights of the three elements, we have, for H, 2 ÷ 1 = 2 atoms; for S, 32 ÷ 32 = 1 atom; for O, 64 ÷ 16 = 4 atoms. An Elementary Study of Chemistry Manifestly, we have come across a phenomenon here which quite eliminates the atomic weight as a determining factor as to position in the Periodic or Natural System or of the elemental properties in general. A Brief Account of Radio-activity The atomic weight is the one quality of importance. The Birth-Time of the World and Other Scientific Essays Again the nitrogen number divided by 18 gives us 14 and a minute fraction as the result, and that is the accepted atomic weight of nitrogen. Occult Chemistry Clairvoyant Observations on the Chemical Elements Radium is characterised by a special spectrum, and its atomic weight, as determined by Madame Curie, is 225; it is consequently the higher homologue of barium in one of the groups of Mendeléef. The New Physics and Its Evolution Their densities increase with their atomic weights, as is shown in the table on opposite page. An Elementary Study of Chemistry All the calculations are based on the atomic weights which are now generally adopted by the majority of chemists. Scientific American Supplement, No. 455, September 20, 1884 The radioactive atom in sinking to a lower atomic weight casts out with enormous velocity an atom of helium. The Birth-Time of the World and Other Scientific Essays Uranium is a rather rare element, though known for over a hundred years, and has an atomic weight of 238.5. Q. E. D., or New Light on the Doctrine of Creation Clarke, chief chemist of the United States Geological Survey, has furnished a table of atomic weights, revised upon the basis of the most recent data and his latest computations. Scientific American Supplement, No. 803, May 23, 1891 In assigning a value to it, however, it is convenient to choose a whole number, and as small a number as possible without making the atomic weight of any other element less than unity. An Elementary Study of Chemistry There is one atom of S in the molecule and the atomic weight of S is 32.1. An Introductory Course of Quantitative Chemical Analysis With Explanatory Notes Still relying on these figures, we find, however, that existing uranium cannot give rise to lead of normal atomic weight. The Birth-Time of the World and Other Scientific Essays These elements of high atomic weight that break down into others of lower atomic weight may be so rare because they have been about all used up in this process. Q. E. D., or New Light on the Doctrine of Creation It would only be necessary for any author of a paper, etc., to state that his analytical figures are based upon "Prof. Clarke's table of atomic weights of December 6, 1890," or some subsequent issue. Scientific American Supplement, No. 803, May 23, 1891 The atomic weights of the elements are given in the Appendix. An Elementary Study of Chemistry It is cheap, but is a comparatively weak antiseptic, its atomic weight being 58.8 in the hydrogen scale, as against 135.5 for chloride of mercury. Scientific American Supplement, No. 514, November 7, 1885 He tried to distract his thoughts from her by going over the atomic weights of the elements…. Love and Mr. Lewisham In decomposing it gives off first a helium atom, weight 4; and after this action has been repeated three times the substance left is radium, atomic weight about 226.4. Q. E. D., or New Light on the Doctrine of Creation "In other words, if the elements are grouped in the order of their atomic weights, it will be found that nearly the same properties recur periodically throughout the entire series." The Gutenberg Webster's Unabridged Dictionary Section P and Q In 1869 the Russian chemist Mendeléeff devised an arrangement of the elements based on their atomic weights, which has proved to be of great service in the comparative study of the elements. An Elementary Study of Chemistry The combining weights either are identical with, or are multiples or submultiples of, the atomic weight. The Gutenberg Webster's Unabridged Dictionary Section C Second, That the atomic weights of the elements as received are correct, i.e., that they do really express with great exactitude the relative weights of the atoms of the individual elements. Scientific American Supplement, No. 324, March 18, 1882 According to the international atomic weights adopted in 1908, the molecular weight of acetylene is 26.016 if O = 16; in round numbers, as ordinarily used, it is 26. Acetylene, the Principles of Its Generation and Use A Practical Handbook on the Production, Purification, and Subsequent Treatment of Acetylene for the Development of Light, Heat, and Power We know that the naturally radioactive elements are all in the group of those with the highest atomic weight. Man or Matter There is evidently a close relation between the properties of an element and its atomic weight. An Elementary Study of Chemistry These atomic weights are absolutely necessary to a clear understanding of the compounds formed by the union or combination of two or more elements. The Story of the Soil; from the Basis of Absolute Science and Real Life, This will be better understood after studying the chapter on atomic weights. An Introduction to Chemical Science When Dalton's atomic theory had been in existence some half century, it was noted that certain numerical relations held good between the atomic weights of elements chemically similar to one another. Darwin and Modern Science But this combination of elements in numerical proportions was exactly what Dalton had noticed as early as 1802, and what bad led him directly to the atomic weights. A History of Science — Volume 4 The three elements following manganese, namely, iron, nickel, and cobalt, have atomic weights near together, and are very similar chemically. An Elementary Study of Chemistry Calling the equivalent, or as it is sometimes called, the atomic weight of hydrogen 1, that of oxygen is 8; that of water is consequently 8 + 1 or 9. Faraday as a Discoverer This is,in fact, the way a formula is ascertained, if the atomic weights of its elements are known. An Introduction to Chemical Science In his "law of octaves," formulated in 1864, he advanced the hypothesis that, if arranged in order of rising atomic weight, the elements fell into groups, so that each eighth element was chemically similar. Darwin and Modern Science The atomic weights of about a score of substances are given in Dalton's first paper, which was read before the Literary and Philosophical Society of Manchester, October 21, 1803. A History of Science — Volume 4 When argon was discovered it was seen at once that there was no place in the table for an element of atomic weight approximately 40. An Elementary Study of Chemistry Radium is itself probably a product of the disintegration of uranium, the heaviest of known metals, with an atomic weight some 240 times greater than that of hydrogen. The Story of Evolution Analysis shows that its weight is half S and half O. As the atomic weight of S is 32, and that of O is 16, what is the symbol for the gas? An Introduction to Chemical Science 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. Darwin and Modern Science But presently renewed determinations of the atomic weights seemed to discountenance this practice, and Prout's alleged law fell into disrepute. A History of Science — Volume 4 Dividing these figures by the atomic weights of the two elements, we get 2 ÷ 1 = 2 for H; 32 ÷ 16 = 2 for O. The formula is therefore H2O2. An Elementary Study of Chemistry The figure so obtained will be the true atomic weight. An Elementary Study of Chemistry It remains to explain how atomic weights are obtained. An Introduction to Chemical Science Divide by the atomic weights of the respective elements, and the quotient will be the number of atoms present. An Elementary Study of Chemistry Subsequently Stas, the pupil of Dumas, undertook a long series of determinations of atomic weights, with the expectation of confirming the Proutian hypothesis. A History of Science — Volume 4 From the following data calculate the atomic weight of sulphur. An Elementary Study of Chemistry From these specific heats calculate the atomic weights of each of the elements. An Elementary Study of Chemistry The atomic weight of an element is its least combining weight, the smallest portion that enters into chemical union, which is, of course, the weight of an atom. An Introduction to Chemical Science A number of triad families were found, but among eighty elements, whose atomic weights range all the way from 1 to 240, such agreements might be mere chance. An Elementary Study of Chemistry But his results seemed to disprove the hypothesis, for the atomic weights of many elements differed from whole numbers by more, it was thought, than the limits of error of the experiments. A History of Science — Volume 4 As will be seen by reference to the table, the melting points and boiling points of the elements of the family increase with their atomic weights. An Elementary Study of Chemistry This generalization is known as the periodic law, and may be stated thus: The properties of elements are periodic functions of their atomic weights. An Elementary Study of Chemistry Atomic Weight of Oxygen.—Suppose we wish to find the atomic weight of oxygen. An Introduction to Chemical Science To compare it with our standard for atomic weights we must further multiply it by 32, since the standard is 1/32 the weight of oxygen molecules. An Elementary Study of Chemistry Why oxygen is chosen as the standard for atomic weights. An Elementary Study of Chemistry The properties of these seven elements therefore vary regularly with their atomic weights, or, in mathematical language, are regular functions of them. An Elementary Study of Chemistry Very recently, however, this unit has been replaced by oxygen, with an atomic weight of 16. An Elementary Study of Chemistry Now the smallest weight of O which unites in any case is its atomic weight. An Introduction to Chemical Science These relative weights of the atoms are spoken of as the atomic weights of the elements. An Elementary Study of Chemistry At one time oxygen was taken as this standard, with the value 100, and the atomic weights of the other elements were expressed in terms of this standard. An Elementary Study of Chemistry But fluorine is an element of small atomic weight, and the one following it, sodium, breaks the regular order, for in it reappear all the characteristic properties of lithium. An Elementary Study of Chemistry If elements were able to combine in only one way,—one atom of one with one atom of another,—the problem of determining the atomic weights would be very simple. An Elementary Study of Chemistry If any compound of O should in future be found in which its combining weight is 8 or 4, that would be called its atomic weight. An Introduction to Chemical Science The ratios thus found would be the same ratios as those between the atoms of the elements, and thus we should have their relative atomic weights. An Elementary Study of Chemistry It would seem more rational to take the element of smallest atomic weight as the standard and give it unit value; accordingly hydrogen was taken as the standard with an atomic weight of 1. An Elementary Study of Chemistry The properties of the elements do not vary continuously, therefore, with atomic weights, but at regular intervals there is a repetition, or period. An Elementary Study of Chemistry This makes the atomic weight of hydrogen equal to 1.008, so that there is but little difference between taking oxygen as 16 and hydrogen as 1 for the unit. An Elementary Study of Chemistry By dividing the numbers in column 4, wt. of O, by 16, the atomic weight of O, we obtain the number of O atoms in the molecule. An Introduction to Chemical Science The oxygen standard for atomic weights has been adopted throughout the text. An Elementary Study of Chemistry The metals of the first of these groups—ruthenium, rhodium, and palladium—have atomic weights near 100 and densities near 12. An Elementary Study of Chemistry Multiply by 32 to make the comparison with the unit for atomic weights. An Elementary Study of Chemistry P has an atomic weight of 31, while its vapor density is 62. An Introduction to Chemical Science Molecular and Atomic Volumes.—We thus see that vapor density and atomic weight are obtained in two quite different ways. An Introduction to Chemical Science Its molecule must consist of 4 atoms, each half the size of the H atom, The vapor density of As is 150, the atomic weight 75. An Introduction to Chemical Science Hg has an atomic weight of 200, a vapor density of 100. An Introduction to Chemical Science Yet the atomic weight of nitrogen as deduced from a study of its gaseous compounds is 14.04. An Elementary Study of Chemistry Ozone has an atomic weight of 16, a vapor density 24. An Introduction to Chemical Science In O both vapor density and atomic weight are 16. An Introduction to Chemical Science Its vapor density at 1,000 degrees is 32; hence its molecular weight is 64, i.e. vapor density x 2; and there are 2 atoms in its molecule at that temperature, molecular weight / atomic weight. An Introduction to Chemical Science Its vapor density is 150, which gives 300 for the molecular weight, while its least combining or atomic weight is 75. An Introduction to Chemical Science All we knew before was that the true atomic weight is some multiple of the equivalent. An Elementary Study of Chemistry Compare the vapor density and the atomic weight of Hg, and explain. An Introduction to Chemical Science This gives 2 atoms of O to the molecule, i.e. the molecular weight / the atomic weight. An Introduction to Chemical Science H is taken as the standard because it has the least atomic weight. An Introduction to Chemical Science The atomic weight of O is 16, which means that its atom weighs 16 times as much as the H atom. An Introduction to Chemical Science In this case the number in the fourth column will be the approximate atomic weight of nitrogen. An Elementary Study of Chemistry Every symbol, then, stands for a definite weight of the element, i.e. its atomic weight, as well as for its atom. An Introduction to Chemical Science S has a vapor density and an atomic weight of 32 each. An Introduction to Chemical Science The least combining weight of an element is its atomic weight; and it is this fact of a least combining weight that leads us to believe the atom to be indivisible. An Introduction to Chemical Science |
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