Atomic Berzelius’ work

Berzelius s own experiments soon convinced him that Dalton was right to conclude that atoms always combine with one another in small whole-number ratios. Berzelius realized that determining the relative weights of all of the elements would be of enormous value to chemistry, because it would then be possible to determine the exact composition of any chemical compound. Without work of this kind, he said, no day could follow the morning dawn. Because he knew of no other chemist who was pursuing this line of research, he decided to do it himself. 

Marignac s life work, which, like that of Stas, consisted in making many precise determinations of atomic weights in order to test William Prout s hypothesis (71), won Berzelius sincerest praise, for he wrote ... 

Dalton s work on relative weights, multiple proportions, and the atomic theory did not have an immediate effect on chemists of his day. Dalton s ideas did provide a framework for determining the empirical formula of compounds, but his table of relative weights was not accurate enough to give consistent results. Many scientists still debated the existence of atoms in the second half of the nineteenth century. Still, little by little, the atomic theory was adopted by chemists as a valid model for the basic structure of matter. While Dalton continued his life as a humble tutor in Manchester, other chemists used Dalton s ideas to establish the atomic theory. Foremost among these was Jons Jacob Berzelius (1779-1848) of Sweden, the foremost chemical authority of the first half of the nineteenth century. 

Dalton s most significant work was done between 1795 and 1805, but fame came later—when the importance of his atomic theory was realized. He became a member of the Royal Society in 1822, received its first Royal Medal in 1826, and was honored with a state pension in 1833, among other honors. He died on July 27, 1844, and 40,000 people attended his funeral. see also Berzelius, Jons Jakob Faraday, Michael Lavoisier, Antoine Priestley, Joseph. 

Wider use of heteropolymolybdates, in both science and industry, has been hindered by the complexity and confusion of the voluminous literature that has accumulated since Berzelius first observed compounds of this type in 1826. Analyses reported in the older literature are often inaccurate since the atomic and molecular weights are so high that small analytical errors produce great errors in the formulas reported degradation was often overlooked, and much of the work was unwittingly performed on mixtures. Accordingly, the earlier literature (though often extremely valuable)... 

Following Lavoisier, chemists had a set of rules and a provisional list of elements to work with. Later, using Dalton s atomic theory and his laws of combining proportions, chemists were able to determine atomic weights and to arrive at molecular formulas indicating the nature and number of the atoms in a molecule. Molecules, the smallest part of a compound that possessed the chemical properties of that compound, could then be classified. Berzelius s classification of mineral compounds rested upon his discoveries about the electrochemical properties of atoms, an explanatory notion grafted onto Dalton s simple atomic theory. Chemists were able to establish research programs based... 

And now Berzelius set himself a still greater task. While working on a new textbook, he came across the work of Richter on the proportions in which substances combine. This started him on an investigation of atomic weights. Dalton s relative... 

Atomic Weight.—In connexion with the atomic weight of sodium, reference has been made to the general methods employed by Berzelius, by Stas, and by Marignac in determining the atomic weights of sodium, potassium, silver, chlorine, bromine, and iodine. At this point it will suffice to summarize the results obtained by these methods, and those derived from the work of modem investigators. 

It is worthwhile to note that Cannizzaro s work led to approximate values of the relative atomic masses. His goal was not to determine highly precise values for atomic masses but rather to pin down the approximate values (for example, to show that oxygen s relative mass was 16 rather than 8). The most precise values for atomic masses were determined by quantitative experiments in which the combining masses of elements were carefully measured, such as in the work of Berzelius. 

As we saw in Chapter 2, the first quantitative information about atomic masses came from the work of Dalton, Gay-Lussac, Lavoisier, Avogadro, Cannizzaro, and Berzelius. By observing the proportions in which elements combine to form various compounds, nineteenth-century chemists calculated relative atomic masses. The modern system of atomic masses, instituted in 1961, is based on 12C (carbon-12) as the standard. In this system I2C is assigned a mass of exactly 12 atomic mass units (amu), and the masses of all other atoms are given relative to this standard. 

Further work on electrochemistry was done by the Swedish chemist Jons Jakob Berzelius (1779-1848), who took Dalton s concept of atoms and combined it with the concept of electrical attraction. Since compounds such as water or metallic oxides could be separated by electrolysis, it seemed reasonable to assume that the elements had an electrochemical nature that accounted for their combination into compounds. Using this idea, Berzelius arranged the elements in a series from oxygen to potassium. While this was very useful for some compounds, it led him to claim that iodine and chlorine could not be elements but had to be oxides of as-yet undiscovered elements because they seemed to form electronegative salts. This problem was cleared up with further analytical work in the 1820s, and Berzelius created a separate category for iodine, chlorine, and bromine. 

The first of these laws was established by Proust in 1799. Dalton himself proved the law of multiple proportions by his researches on olefiant gas and carburetted hydrogen, and on other substances. The third law first became apparent from the neglected work of Richter on the quantitative neutralisation of acids by bases (p. 146). Soon after the publication of the Atomic Theory, the great Swedish chemist, Berzelius, wrote to Dalton saying that the theory of multiple proportions is a mystery without the atomic hypothesis. ... 

The most notable of Berzehus s contributions to chemistry was his development of a rational system of atomic symbols. Around 1810 Berzelius was working to confirm John Dalton s atomic theory as well as Proust s... 

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