Jöns Jacob Berzelius

How to use this course

Jöns Jacob Berzelius gave chemistry its working tools. He turned Dalton’s atomic theory into numbers by measuring the combining proportions of nearly every known element with an accuracy no one had approached. He invented the system of letter symbols, H, O, C, Na, Cl, that every chemist now writes. He discovered or first isolated cerium, selenium, silicon, zirconium and thorium. He coined the words isomerism, catalysis, polymer, allotropy and protein. And for three decades, through his textbook and his annual reports on the progress of the science, he was the arbiter of what counted as established chemistry in Europe. His great theory, electrochemical dualism, was eventually abandoned, and the story of why is part of this course.

Each technical lesson opens with a paragraph for the general reader, then gives the key results in modern form, reconstructs Berzelius’s reasoning, and ends with exercises whose solutions are folded. Berzelius used a scale on which oxygen = 100. The exercises use modern atomic weights (carbon-12 = 12) unless they say otherwise, and Lesson 06 shows how to convert.

Timeline

Östergötland and Linköping, 1779–1796

Jöns Jacob Berzelius was born on 20 August 1779 at Väversunda in the province of Östergötland, in southern Sweden, where his family was staying for the summer. His father, Samuel Berzelius, was a schoolmaster in Linköping and died when Jöns Jacob was very young. His mother, Elisabet Dorotea Sjösteen, married Anders Ekmarck, a pastor, who gave the boy his first schooling. She died when he was still a child, and he was raised by relatives, an unhappy period he remembered without affection.

In 1793 he entered the gymnasium at Linköping, the cathedral school. He was a poor and somewhat unruly pupil but a passionate collector of plants and insects, and natural history drew him toward medicine, one of the few routes for a poor boy into science. To earn money he worked for a time as a private tutor on a farm.

In 1796 he went to Uppsala to study medicine. Chemistry at Uppsala was taught by Anders Gustaf Ekeberg, the discoverer of tantalum, but Berzelius received little practical instruction. He taught himself by reading and by experiment, and he learned laboratory craft, including glassblowing, while working in a pharmacy. One of his first independent efforts was to repeat Carl Wilhelm Scheele’s experiments on the preparation of oxygen.

Uppsala, Medevi and the voltaic pile, 1796–1802

In the summer of 1800 Berzelius worked as assistant to the physician at the Medevi mineral springs in Östergötland. He analysed the spring water, one of his first pieces of chemical research. Analysis of waters and minerals, precise, quantitative and patient, would remain the core of his science.

The same year brought news of Alessandro Volta’s pile. Berzelius built one of his own from sixty pairs of zinc and copper discs and used it in medicine. His doctoral thesis, defended at Uppsala in 1802, tested galvanic treatment on patients and reported honestly that it produced no improvement. The pile itself mattered more to him than the therapy. It had shown that electricity could decompose water, and he wanted to know what it could do to salts.

After his degree he moved to Stockholm, where he became an unpaid assistant at the school of surgery and worked as a physician to the poor. He had almost no money. What changed his life was a meeting with a wealthy mine owner and amateur chemist.

Stockholm and Hisinger, 1802–1810

Wilhelm Hisinger owned the iron mines at Riddarhyttan and an estate at Skinnskatteberg. He had a strong interest in mineralogy and recognized Berzelius’s analytical skill. He gave him lodgings and a laboratory in a house in Stockholm, where Berzelius worked in a converted kitchen for many years. Together, in 1803, they published experiments on the action of the voltaic pile on salts (Lesson 04). In the same year, analysing a heavy mineral from the Bastnäs mine near Riddarhyttan, they found the oxide of a new element, which they named cerium after the asteroid Ceres, discovered two years before. Martin Heinrich Klaproth found it independently in Berlin.

In 1807 Berzelius became professor of medicine and pharmacy at the Stockholm medical college, which became the Karolinska Institute in 1810, with him as professor of chemistry and pharmacy. He lectured on animal chemistry and analysed body fluids, bile and muscle, but found the field frustrating. He began writing a textbook for medical students, Lärbok i kemien, whose first volume appeared in 1808. Writing it led him to the problem that would define his career. He found that the existing data on the composition of compounds were too inaccurate to teach from, and he began to measure them himself.

In 1808 he was elected to the Royal Swedish Academy of Sciences, and in the same year he and Magnus Pontin electrolysed salt solutions over a mercury cathode, obtaining amalgams of calcium and barium. They sent word to Humphry Davy, who used the method to obtain the alkaline-earth metals. Early in 1809 Berzelius learned of John Dalton’s atomic theory. He saw that his program of exact analysis could test it.

Electrolysis of salts and electrochemical dualism

For the general reader. When Berzelius and Hisinger passed a current through salt solutions in 1803, the acid always went to one pole and the base to the other. Berzelius built a whole theory of chemistry on this. Every atom carries electric charge, some more positive and some more negative, and chemical compounds are held together by the attraction of opposite charges. The theory organized inorganic chemistry for decades and then failed in organic chemistry.

The 1803 experiments

Berzelius and Hisinger electrolysed solutions of salts such as sodium sulfate, potassium chloride and ammonium chloride. They found that oxygen and acids collected at the positive pole, while hydrogen, alkalis, earths and metals collected at the negative. Combustible bodies and bases went one way, oxygen and acids the other. Davy reached the same conclusion independently in his Bakerian Lecture of 1806, and the two men’s work established electrolysis as a tool of chemical analysis.

In this scheme gypsum is lime plus sulfuric acid (in the old sense of the anhydride), CaO·SO₃. Saltpetre is potash plus nitric anhydride, and alum is a double salt of potassium sulfate and aluminium sulfate. Oxygen, sitting at the negative end, is the universal partner. The theory gave a clear rule for which substances combine, explained why acids neutralize bases, and fitted the facts of electrolysis. It also made Berzelius slow to accept Davy’s chlorine (Lesson 08 of the Davy module). He accepted chlorine as an element only after years of resistance.

Where dualism broke

In the 1830s Jean-Baptiste Dumas and Auguste Laurent showed that chlorine can replace hydrogen in organic compounds, atom for atom, while the compound keeps much of its character. Dumas’s trichloroacetic acid (1838–39) is still an acid much like acetic acid. On dualism this is impossible: strongly negative chlorine should not be able to take the place of positive hydrogen without changing everything. Berzelius resisted the substitution theory to the end of his life. Modern chemistry kept a version of his idea in the concepts of electronegativity and ionic bonding, but the covalent bond, in which electrons are shared, has no place in dualism.

Definite proportions and the art of analysis

For the general reader. Is the composition of a compound fixed, or can elements combine in any proportion? In the early 1800s this was a live dispute. Berzelius settled it with hundreds of exact analyses. He also showed that when two elements form several compounds, the proportions follow simple whole numbers. His results were the evidence that made Dalton’s atoms believable.

Two laws

Joseph Louis Proust had defended the first law against Claude Louis Berthollet, who argued that composition could vary continuously. Berzelius set out from 1810 to test both laws on as many compounds as possible. He prepared, for example, lead oxides and lead sulfide, oxidized and sulfidized known weights of metal, and checked that the oxygen in a metal sulfate bore a fixed ratio to the oxygen in its base. He devised much of his own apparatus and refined techniques of filtration, ignition and weighing. He insisted on reaching the same composition by at least two independent reactions, and published his methods so others could repeat them.

The oxygen rule

One of his most useful generalizations concerned salts. In a neutral sulfate the oxygen of the acid is three times that of the base; in CaO·SO₃ there is one O in the base and three in the acid. Similar fixed ratios hold for other families of salts. Berzelius used such ratios to deduce formulas of compounds where direct analysis was hard, and to check analyses for errors.

Atomic weights: Dulong–Petit and isomorphism

For the general reader. Chemical analysis gives the ratio of masses in a compound. To turn that into the relative weight of atoms you must know how many atoms of each kind are present, which is exactly what you do not know. Dalton guessed by a rule of simplicity, and often guessed wrong. Berzelius used every clue he could find: gas volumes, the shapes of crystals, and the heat needed to warm a solid. His 1826 table was close to modern values for most elements.

The ambiguity

Analysis of water gives about 8 g of oxygen per gram of hydrogen. If water is HO, oxygen weighs 8; if H₂O, 16. Each analysis fixes an equivalent weight, and atomic weights are integer multiples of it. Berzelius took oxygen as his standard, with O = 100. From Gay-Lussac’s law of combining volumes he took it that equal volumes of the elementary gases contain equal numbers of atoms, so water, formed from two volumes of hydrogen and one of oxygen, has two atoms of hydrogen to one of oxygen. This gave him H = 6.24 on his scale, about 1/16 of oxygen, and correct formulas for water, ammonia and the hydrogen halides, where Dalton had written HO and NH.

The law has a simple modern explanation. In a solid each atom vibrates in three dimensions, and by equipartition each of the three oscillators carries \(k_BT\) of energy on average, giving \(3R\) per mole. Light, hard solids such as diamond fall below the law at room temperature because their vibrations are not fully excited, a quantum effect that Einstein explained in 1907.

Mitscherlich found that the phosphates and arsenates of the same base crystallize alike, and Berzelius used such series to fix formulas. Since alumina, iron(III) oxide and chromium(III) oxide are isomorphous, all three are M₂O₃. In 1826 Berzelius revised his table with these tools. Many of his earlier metal oxides, written as MO₂ in 1813, became MO, halving the atomic weights. For silver and the alkali metals he kept formulas such as AgO and KO, so his atomic weights for these elements were double the modern ones; Regnault’s specific-heat measurements and Cannizzaro’s system later corrected them.

The language of symbols

For the general reader. Dalton drew atoms as circles with dots and lines inside, impossible to print and hard to remember. In 1813 Berzelius proposed using the first letter or two of each element’s Latin name, with numbers to show how many atoms combine. The idea was so simple and useful that, with small changes, it is the notation every chemist uses today.

The rules of 1813

Berzelius set out his notation in the third section of a long essay on chemical proportions, published in Thomas Thomson’s Annals of Philosophy in 1813–14. He argued that symbols should be letters, so they could be written and printed easily. His rules were:

• Each element is denoted by the initial letter of its Latin name: O (oxygenium), H (hydrogenium), C (carbonicum), S (sulphur).
• If two elements share an initial, a non-metal keeps the single letter and metals take two letters: C for carbon, Co for cobalt, Cu for copper (cuprum).
• If two metals share the first two letters, the first consonant they do not share is added: St for stibium (antimony) and Sn for stannum (tin). Antimony later became Sb.
• Each symbol stands for one “volume” or atom with a definite weight. A number in front multiplies; a number written above the symbol counts the atoms in a compound: CuO² + 2SO³ for his copper sulfate of 1813.

Later he added abbreviations that fitted his dualistic chemistry: a dot over a symbol for each oxygen atom, a comma for each sulfur atom, and a bar through a symbol for a double atom. Thus potash could be written \(\dot{\mathrm K}\) and sulfur trioxide as S with three dots. Liebig and others moved the numbers from superscripts to subscripts in the 1830s, and the dots and bars fell out of use.

New elements: cerium, selenium, silicon, thorium

For the general reader. An analytical chemist who weighs everything notices when the numbers do not add up. Berzelius’s laboratory found more new elements than any other of its time. He discovered cerium, selenium and thorium, first prepared silicon and zirconium as elements, and his students found lithium, vanadium and several rare earths. Many of these discoveries came from Swedish minerals.

Cerium (1803)

The heavy mineral of Bastnäs, now called cerite, had been thought to be a tungsten ore. Berzelius and Hisinger found that it contained the oxide of an unknown metal, whose salts were distinct from those of yttria, the rare earth that Johan Gadolin had found in 1794. They named it after the asteroid Ceres. Their cerium oxide was in fact a mixture: in 1839 and 1842 Berzelius’s assistant Carl Gustaf Mosander separated lanthanum and “didymium” from it, beginning the long unravelling of the rare earths.

Selenium (1817)

Berzelius and Johan Gottlieb Gahn were partners in a sulfuric acid works at Gripsholm that burned pyrite from the Falun mine. A red deposit formed in the lead chambers. Burned, it smelled of horseradish, which suggested tellurium, but Falun had no tellurium. Berzelius concluded that the deposit contained a new element closely resembling sulfur and tellurium, and named it selenium after the Greek for moon, as tellurium was named after the earth.

In 1824 he obtained amorphous silicon (“silicium”) this way, and showed it burns in air to silica, establishing that silica is an oxide. Zirconium followed the same year, though not pure. In 1828 Jens Esmark sent him a black mineral found by his son, the priest Morten Thrane Esmark, on the island of Løvøya in Norway. Berzelius found the oxide of a new element, which he named thorium after the Norse god Thor and published in 1829. He had used the name once before, for a supposed earth that in 1824 he showed was yttrium phosphate. He isolated impure thorium by reducing a potassium thorium fluoride with potassium. In his laboratory Johan August Arfwedson found lithium in petalite (1817), and Nils Gabriel Sefström found vanadium in Swedish iron (1830).

Isomerism, polymerism and radicals

For the general reader. Before 1830 chemists assumed that the same atoms in the same proportions must make the same substance. Then several pairs of compounds turned up with identical analyses and different properties. Berzelius at first suspected bad analyses, checked them himself, and then gave the phenomenon a name, isomerism. The word became the starting point for structural chemistry: what matters is not only which atoms, but how they are arranged.

The cases

• Cyanate and fulminate. In the mid-1820s Friedrich Wöhler analysed silver cyanate, and Justus von Liebig silver fulminate, which is explosive. Their analyses agreed. Each at first thought the other had made an error.
• Urea. In 1828 Wöhler heated ammonium cyanate and obtained urea, an organic substance from urine, of exactly the same composition.
• Tartaric and racemic acids. Gay-Lussac and Berzelius found that tartaric acid and racemic acid, from the tartar of wine, have the same composition but different solubilities and crystals. In 1830 Berzelius proposed the name isomeric for such bodies.

In modern terms, cyanate is \(\mathrm{[OCN]^-}\) and fulminate \(\mathrm{[CNO]^-}\): the same atoms bonded in a different order. Urea \(\mathrm{CO(NH_2)_2}\) and ammonium cyanate \(\mathrm{NH_4OCN}\) are constitutional isomers, and racemic acid is a 1 : 1 mixture of the two mirror-image forms of tartaric acid, as Louis Pasteur showed in 1848.

Radicals

To extend dualism to organic chemistry, Berzelius treated organic compounds as oxides of compound radicals, groups of carbon and hydrogen that act like elements. Liebig and Wöhler’s 1832 study of the benzoyl radical, which passes unchanged through a series of reactions, delighted him. But as substitution reactions accumulated (Lesson 04), the radical theory merged into the type theories of Dumas, Laurent and Gerhardt, and later into the structural theory of Kekulé and Couper.

Catalysis

For the general reader. Some substances speed up a chemical reaction without being used up. Acid turns starch into sugar and is still there at the end; a little platinum makes hydrogen burn in air at room temperature. In his annual report of 1835 Berzelius gathered these scattered observations under one name, catalysis, and suggested that the same power is at work in living things. Catalysis now underlies most of the chemical industry and all of biochemistry.

The observations

By 1835 chemists had collected many puzzling cases. Gottlieb Kirchhoff found in 1811 that dilute acid converts starch to glucose. Louis Jacques Thénard found that some metals and oxides decompose hydrogen peroxide without changing. Johann Wolfgang Döbereiner found in 1823 that hydrogen ignites on contact with platinum sponge, the principle of his lighter. Eilhard Mitscherlich in 1834 described the formation of ether from alcohol by sulfuric acid as “contact” action. Berzelius proposed that these substances exert a catalytic force, by which they awaken affinities that are otherwise dormant at the given temperature. He suggested that in living organisms thousands of such catalytic processes take place, which is how enzymes are understood today.

Berzelius’s “force” explained nothing mechanistically, and Liebig criticized it for that reason. Wilhelm Ostwald gave the modern kinetic definition at the end of the century, and Sabatier and Haber made catalysis the basis of industrial chemistry. The insight that remains Berzelius’s is the classification: a single phenomenon connects acid hydrolysis, surface reactions on metals and the chemistry of life.

The Stockholm school and the annual reports

Berzelius’s laboratory in Stockholm was small and simple. It was also the most important training ground in chemistry for a generation. Students came from Sweden and especially from Germany to learn his methods of analysis. Eilhard Mitscherlich worked there from 1819 to 1821, and Friedrich Wöhler in 1823–24, beginning a friendship and correspondence that lasted the rest of Berzelius’s life. Wöhler translated most of his writings into German. Heinrich and Gustav Rose, Christian Gmelin and Gustav Magnus also studied with him. Swedish pupils and assistants included Arfwedson, Sefström and Mosander.

His journeys were scientific events. In London in 1812 he met Davy, Wollaston and the Royal Society circle. In 1818–19 he spent about fourteen months travelling through England, France, Switzerland and Germany. In Paris he was received as a celebrity, met Gay-Lussac, Biot and the mineralogist Haüy, and worked at Arcueil in Berthollet’s house with Pierre Louis Dulong on the atomic weights of hydrogen, nitrogen and carbon. In 1818 he was elected permanent secretary of the Royal Swedish Academy of Sciences, which he revived over thirty years, and King Karl XIV Johan ennobled him.

The textbook and the reports

His Lärbok i kemien, begun in 1808, grew through many editions and translations, above all Wöhler’s German version, into the standard reference of the science. From 1821–22 he wrote for the Academy an annual report on progress in physics and chemistry, translated into German as the Jahresbericht. These reports summarized and judged everything of importance published that year. They made him the most influential critic in chemistry, and the place where terms like isomerism and catalysis were first proposed.

Baron, critic, legacy, 1830–1848

In 1835, at 56, Berzelius married Elisabeth Poppius, the 24-year-old daughter of a Swedish cabinet minister. In the same year the king made him a baron. They had no children. He received the Copley Medal of the Royal Society in 1836, and in 1837 was elected to the Swedish Academy. He suffered for years from gout, and his health declined in the 1840s.

His last years were marked by controversy. The new organic chemistry of Dumas, Laurent and Gerhardt rejected his dualism, and his reports became increasingly defensive. Younger chemists, Liebig among them, came to see him as an obstacle as well as a founder. He kept working on analysis and on his textbook until near the end. He died at his home in Stockholm on 7 August 1848 and was buried at Solna. A statue in Berzelii Park in Stockholm was unveiled in 1853.

Legacy

• Atomic weights: the first accurate table for almost all known elements, the empirical foundation of the atomic theory until Cannizzaro’s reform of 1858–60.
• Notation: letter symbols and formulas, adopted universally with only small changes.
• Elements: cerium, selenium and thorium discovered; silicon and zirconium first isolated; lithium, vanadium, lanthanum and other rare earths found in his laboratory.
• Concepts and words: isomerism, polymer, allotropy, catalysis and protein; electrochemical dualism, ancestor of the ideas of electronegativity and ionic bonding.
• Analytical method: new standards of gravimetric analysis and of laboratory technique, and a generation of chemists trained in Stockholm.

Sources and further reading

Biography

1. Jöns Jacob Berzelius, Wikipedia (with extensive references).
2. Science History Institute, Jöns Jakob Berzelius.
3. J. L. Marshall and V. R. Marshall, Rediscovery of the elements: Jöns Jacob Berzelius, The Hexagon.
4. G. Weisz, Jöns Jacob Berzelius: physician, scientist and globetrotter, Hektoen International, 2019.
5. J. E. Jorpes, Jac. Berzelius: His Life and Work, Almqvist & Wiksell, 1966; University of California Press, 1970.
6. E. M. Melhado, Jacob Berzelius: The Emergence of His Chemical System, Almqvist & Wiksell, 1980.
7. Dictionary of Scientific Biography, Berzelius, Jöns Jacob, via Encyclopedia.com.

Science

1. J. J. Berzelius, Essay on the cause of chemical proportions, and on some circumstances relating to them: together with a short and easy method of expressing them, Annals of Philosophy 2–3 (1813–14). Section on chemical signs, Classic Chemistry, Le Moyne College.
2. J. J. Berzelius, Essai sur la théorie des proportions chimiques et sur l’influence chimique de l’électricité, Paris, 1819.
3. W. Hisinger and J. J. Berzelius, Versuche, betreffend die Wirkung der elektrischen Säule auf Salze und auf einige von ihren Basen, Neues allgemeines Journal der Chemie 1 (1803).
4. P. L. Dulong and A. T. Petit, Recherches sur quelques points importants de la théorie de la chaleur, Annales de chimie et de physique 10 (1819).
5. Catalysis, Wikipedia, history section, on Berzelius’s 1835 report.
6. Isomer, Wikipedia, history section.
7. Selenium and Thorium, Wikipedia, history sections.
8. A. J. Rocke, Chemical Atomism in the Nineteenth Century: From Dalton to Cannizzaro, Ohio State University Press, 1984.