MOLYBDENUM [[[symbol]], Mo; atomic weight, 96 (0=16)] a metallic chemical element.
Many varying values have been given for the atomic weight of molybdenum.
As the atomic weight of the element increases, it is found that the solubility of the sulphates in water decreases.
GERMANIUM (symbol Ge, atomic weight 72.5); one of the metallic elements included in the same natural family as carbon, silicon, tin and lead.
The atomic weight was determined by Berzelius, Erdmann and Marchand, Dumas and Stas.
By reducing the human mind to a series of unrelated atomic sensations, this teaching destroyed the possibility of knowledge, and further, by representing man as a "being who is simply the result of natural forces," it made conduct, or any theory of conduct, unmeaning; for life in any human, intelligible sense implies a personal self which (1) knows what to do, (2) has power to do it.
The atomic weight of ruthenium was determined by A.
Newlands in England, that if they are arranged in the order of their atomic weights they fall into groups in which similar chemical and physical properties are repeated at periodic intervals; and in particular he showed that if the atomic weights are plotted as ordinates and the atomic volumes as abscissae, the curve obtained presents a series of maxima and minima, the most electro-positive elements appearing at the peaks of the curve in the order of their atomic weights.
The atomic weight of the element has been determined by analysis.
Dalton (1803) gave the atomic theory a quantitative form, and showed that, by means of it, a vast number of the facts of chemistry could be predicted or explained.
Otherwise Berthollet's position would have been a much stronger one, and the atomic theory might have had to wait a long while for acceptance.
It is now agreed that the molecule of water contains two atoms of hydrogen and one of oxygen, so that the atomic weight of oxygen becomes 16, and similarly that the molecule of ammonia contains three atoms of hydrogen and one of nitrogen, and that consequently the atomic weight of nitrogen is 14.
The atomic theory has been of priceless value to chemists, but it has more than once happened in the history of science that a hypothesis, after having been useful in the discovery Present and the co-ordination of knowledge, has been aban- position doned and replaced by one more in harmony with later of the discoveries.
Some distinguished chemists have thought atomic that this fate may be awaiting the atomic theory, and that in future chemists may be able to obtain all the guidance they need from the science of the transformations of energy.
The atomic weight was determined by Cleve.
The atomic weight of cadmium was found by 0.
RUTHENIUM [[[symbol]] Ru, atomic weight To' 7 (O = 0)1, in chemistry, a metallic element, found associated with platinum, in platinum ore and in osmiridium.
His book on Die modernen Theorien der Chemie, which was first published in Breslau in 1864, contains a discussion of relations between the atomic weights and the properties of the elements.
In fact, he did so much to make the atomic theory of matter probable that he is popularly regarded as its originator.
The conclusion that each element had a definite atomic weight, peculiar to it, was the new idea that made his speculations fruitful, because it allowed of quantitative deduction and verification.
Apart from the atomic theory there is no obvious reason why this should be so.
The discovery of this law is due to Dalton; it is a direct deduction from his atomic theory.
As Dalton said, "The doctrine of definite proportions appears mysterious unless we adopt the atomic hypothesis."
In water and in ethylene experiment shows that 8 parts by weight of oxygen and 6 parts of carbon, respectively, are in union with one part of hydrogen; also, if the diagrams are correct, these numbers must be in the ratio of the atomic weights of oxygen and carbon.
The above statement does not by any means exhaust the possible predictions that can be made from the atomic theory, but it shows how to test the theory.
If chemical compounds can be proved by experiment to obey these laws, then the atomic theory acquires a high degree of probability; if they are contradicted by experiment then the atomic theory must be abandoned, or very much modified.
The question is, however, vital to the atomic theory.
The neutralization of acids by bases affords many illustrations, known even before the atomic theory, of the truth of the statement.
The above gives some idea of the evidence that has been accumulated in favour of the laws of chemical combination, laws which can be deduced from the atomic theory.
On account of this difficulty, the atomic weights published by Dalton, and the more accurate ones of Berzelius, were not always identical with the values now accepted, but were often simple multiples or submultiples of these.
In 1831, from a study of the specific heats of compounds, he formulated "Neumann's law," which expressed in modern language runs: "The molecular heat of a compound is equal to the sum of the atomic heats of its constituents."