Otto Hönigschmid (13 March 1878 in

Hořovice Hořovice (; german: Horschowitz, Horvitz, Horowitz) is a town in Beroun District in the Central Bohemian Region of the Czech Republic. It has about 6,900 inhabitants. Administrative parts Hořovice is made up of only one administrative part. His ...

– 14 October 1945 in

Munich Munich ( ; german: München ; bar, Minga ) is the capital and most populous city of the States of Germany, German state of Bavaria. With a population of 1,558,395 inhabitants as of 31 July 2020, it is the List of cities in Germany by popu ...

) was a

Czech Czech may refer to: * Anything from or related to the Czech Republic, a country in Europe ** Czech language ** Czechs, the people of the area ** Czech culture ** Czech cuisine * One of three mythical brothers, Lech, Czech, and Rus' Places *Czech, ...

Austria Austria, , bar, Östareich officially the Republic of Austria, is a country in the southern part of Central Europe, lying in the Eastern Alps. It is a federation of nine states, one of which is the capital, Vienna, the most populous ...

n chemist. He published the first widely accepted experimental proof of isotopes along with

Stefanie Horovitz Stefanie Horovitz (1887–1942) (Stefania Horovitz or Stephanie Horowitz) was a Polish-Jewish chemist known for experimental work proving the existence of isotopes. Between approximately 1914-1918, she worked with Otto Hönigschmid at the Radium ...

. Throughout his career he worked to precisely define atomic weights for over 40 elements, and served on committees with the purpose of adopting internationally agreed upon values. After his home and laboratory in Munich were destroyed in

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

, he committed suicide in 1945.

Education

Hönigschmid studied organic chemistry at the

Charles University in Prague Charles University ( cs, Univerzita Karlova, UK; la, Universitas Carolina; german: Karls-Universität), also known as Charles University in Prague or historically as the University of Prague ( la, Universitas Pragensis, links=no), is the oldest an ...

under the guidance of

Guido Goldschmiedt Guido Goldschmiedt (May 29, 1850 – August 6, 1915) was an Austrian chemist. During his career, he collaborated with Bunsen in Heidelberg and Baeyer in Straßburg. In 1891, he became full professor at the University of Vienna and later at the Un ...

(the discoverer of the structure of

papaverine Papaverine (Latin ''papaver'', "poppy") is an opium alkaloid antispasmodic drug, used primarily in the treatment of visceral spasms and vasospasms (especially those involving the intestines, heart, or brain), occasionally in the treatment of erec ...

). Additionally, he worked as a student researcher in

Paris Paris () is the capital and most populous city of France, with an estimated population of 2,165,423 residents in 2019 in an area of more than 105 km² (41 sq mi), making it the 30th most densely populated city in the world in 2020. S ...

under

Henri Moissan Ferdinand Frédéric Henri Moissan (28 September 1852 – 20 February 1907) was a French chemist and pharmacist who won the 1906 Nobel Prize in Chemistry for his work in isolating fluorine from its compounds. Moissan was one of the original mem ...

from 1904 to 1906. He was

habilitated Habilitation is the highest university degree, or the procedure by which it is achieved, in many European countries. The candidate fulfills a university's set criteria of excellence in research, teaching and further education, usually including a ...

in 1908 upon publication of a thesis on carbide and silicide.

Career and Scientific Research

In 1909, Hönigschmid worked under Theodore Richards at

Harvard University Harvard University is a private Ivy League research university in Cambridge, Massachusetts. Founded in 1636 as Harvard College and named for its first benefactor, the Puritan clergyman John Harvard, it is the oldest institution of higher le ...

to determine the official weight of

calcium Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to ...

. During this year he learned Richards' Nobel Prize winning methods for precisely determining atomic weights, which earned Hönigschmid credibility in the field. From 1911-18 he was a professor and directory of the laboratory of

inorganic In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemist ...

and

analytical chemistry Analytical chemistry studies and uses instruments and methods to separate, identify, and quantify matter. In practice, separation, identification or quantification may constitute the entire analysis or be combined with another method. Separati ...

at the Prague Polytechnic University. He was simultaneously involved in research at the Radium Institute of Vienna, traveling back and forth between the two cities. He was asked by

Frederick Soddy Frederick Soddy FRS (2 September 1877 – 22 September 1956) was an English radiochemist who explained, with Ernest Rutherford, that radioactivity is due to the transmutation of elements, now known to involve nuclear reactions. He also prove ...

and

Kazimierz Fajans Kazimierz Fajans (Kasimir Fajans in many American publications; 27 May 1887 – 18 May 1975) was a Polish American physical chemist of Polish-Jewish origin, a pioneer in the science of radioactivity and the discoverer of chemical element protac ...

to determine precise atomic weights of lead from radioactive sources in support of their

radioactive displacement law of Fajans and Soddy The law of radioactive displacements, also known as Fajans's and Soddy's law, in radiochemistry and nuclear physics, is a rule governing the Nuclear transmutation, transmutation of elements during radioactive decay. It is named after Frederick Sod ...

, which had not yet been credibly proven by experimental means. At the suggestion of

Lise Meitner Elise Meitner ( , ; 7 November 1878 – 27 October 1968) was an Austrian-Swedish physicist who was one of those responsible for the discovery of the element protactinium and nuclear fission. While working at the Kaiser Wilhelm Institute on rad ...

, he recruited Stefanie Horovitz in 1914 to work from his Vienna lab processing lead from uranium-rich pitchblende and measuring its atomic weight to the thousandth of a gram. The two co-published their results showing a significant difference in weight between the uranium lead (206.736 g/mol) and standard lead (207.190 g/mol), thereby providing the first authoritative proof of the existence of isotopes. Within two years, Hönigschmid and Horovitz demonstrated the second known case of isotopes by showing that

ionium Thorium (90Th) has seven naturally occurring isotopes but none are stable. One isotope, 232Th, is ''relatively'' stable, with a half-life of 1.405×1010 years, considerably longer than the age of the Earth, and even slightly longer than the gene ...

, a recently discovered element, was in fact

thorium-230 Thorium (90Th) has seven naturally occurring isotopes but none are stable. One isotope, 232Th, is ''relatively'' stable, with a half-life of 1.405×1010 years, considerably longer than the age of the Earth, and even slightly longer than the gene ...

. In 1918, he moved to Germany to teach at Munich University, where he founded a laboratory specifically for research with atomic weights. He and his colleagues worked up until 1941 to precisely define atomic weights of over 40 elements. Notable contributions redefined values for

silver Silver is a chemical element with the Symbol (chemistry), symbol Ag (from the Latin ', derived from the Proto-Indo-European wikt:Reconstruction:Proto-Indo-European/h₂erǵ-, ''h₂erǵ'': "shiny" or "white") and atomic number 47. A soft, whi ...

niobium Niobium is a chemical element with chemical symbol Nb (formerly columbium, Cb) and atomic number 41. It is a light grey, crystalline, and ductile transition metal. Pure niobium has a Mohs hardness rating similar to pure titanium, and it has sim ...

tantalum Tantalum is a chemical element with the symbol Ta and atomic number 73. Previously known as ''tantalium'', it is named after Tantalus, a villain in Greek mythology. Tantalum is a very hard, ductile, lustrous, blue-gray transition metal that is ...

, and

phosphorus Phosphorus is a chemical element with the symbol P and atomic number 15. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly reactive, phosphorus is never found as a free element on Ear ...

. Contributing to the work of

Ernest Rutherford Ernest Rutherford, 1st Baron Rutherford of Nelson, (30 August 1871 – 19 October 1937) was a New Zealand physicist who came to be known as the father of nuclear physics. ''Encyclopædia Britannica'' considers him to be the greatest ...

and

Marie Curie Marie Salomea Skłodowska–Curie ( , , ; born Maria Salomea Skłodowska, ; 7 November 1867 – 4 July 1934) was a Polish and naturalized-French physicist and chemist who conducted pioneering research on radioactivity. She was the first ...

, Hönigschmid prepared

radium Radium is a chemical element with the symbol Ra and atomic number 88. It is the sixth element in group 2 of the periodic table, also known as the alkaline earth metals. Pure radium is silvery-white, but it readily reacts with nitrogen (rather t ...

standards for comparison in 1912 and again in 1934. Additionally, he served as the chairman of the German Atomic Weight Commission from 1920-1930, and in 1930 became the German representative in the Atomic Weights Committee of the International Union of Chemistry. This work was instrumental in the adoption of precisely defined atomic weights in the international scientific community.

Awards

He won the Haitinger Prize of the Austrian Academy of Sciences in 1913, and the

Liebig Medal The Liebig Medal (German: ''Liebig-Denkmünze'') was established by the (''Verein Deutscher Chemiker'') in 1903 to celebrate the centenary of Justus von Liebig. Since 1946 it has been awarded by the Society of German Chemists (''Gesellschaft De ...

in 1940.

Death

Much of Hönigschmid's work, his home, and his laboratory in Munich were destroyed during

. Facing difficulties with his health and housing, he committed suicide alongside his wife in 1945. The two had been staying with the widow of

Hans Fischer Hans Fischer (; 27 July 1881 – 31 March 1945) was a German organic chemist and the recipient of the 1930 Nobel Prize for Chemistry "for his researches into the constitution of haemin and chlorophyll and especially for his synthesis of haem ...

, a friend and colleague who had also killed himself a few months prior.

References

External links

Contains short biography of Hönigschmid (in Czech)
* {{DEFAULTSORT:Honigschmid, Otto 1878 births 1945 suicides People from Hořovice Austrian chemists Charles University alumni Ludwig Maximilian University of Munich alumni Harvard University faculty Czech chemists Suicides in Germany Academic staff of Czech Technical University in Prague Chemists from the Austro-Hungarian empire