Henri Becquerel

Antoine Henri Becquerel (/ˌbɛkəˈrɛl/;[2] French: [ɑ̃ʁi bɛkʁɛl]; 15 December 1852 – 25 August 1908) was a French engineer, physicist, Nobel laureate, and the first person to discover evidence of radioactivity. For work in this field he, along with Marie Skłodowska-Curie (Marie Curie) and Pierre Curie,[3] received the 1903 Nobel Prize in Physics. The SI unit for radioactivity, the becquerel (Bq), is named after him.

Antoine Henri Becquerel
Portrait of Antoine-Henri Becquerel
Henri Becquerel, French physicist
Born15 December 1852
Died25 August 1908 (aged 55)
Alma materÉcole Polytechnique
École des Ponts et Chaussées
Known forDiscovery of radioactivity
Scientific career
FieldsPhysics, chemistry
InstitutionsConservatoire des Arts et Metiers
École Polytechnique
Muséum National d'Histoire Naturelle
Doctoral studentsMarie Skłodowska-Curie
Henri Becquerel signature
He is the father of Jean Becquerel, son of Edmond Becquerel, and grandson of Antoine César Becquerel


Early life

Becquerel was born in Paris into a wealthy family which produced four generations of physicists: Becquerel's grandfather (Antoine César Becquerel), father (Alexandre-Edmond Becquerel), and son (Jean Becquerel).[4] Henri started off his education by attending the Lycée Louis-le-Grand school, a prep school in Paris.[4] He studied engineering at the École Polytechnique and the École des Ponts et Chaussées.[5] In 1874, Henri married Lucie Zoé Marie Jamin, who would die while giving birth to their son, Jean.[6] In 1890 he married Louise Désirée Lorieux.[7]


In Becquerel's early career, he became the third in his family to occupy the physics chair at the Muséum National d'Histoire Naturelle in 1892. Later on in 1894, Becquerel became chief engineer in the Department of Bridges and Highways before he started with his early experiments. Becquerel's earliest works centered on the subject of his doctoral thesis: the plane polarization of light, with the phenomenon of phosphorescence and absorption of light by crystals.[8] Early in his career, Becquerel also studied the Earth's magnetic fields.[8]

Becquerel's discovery of spontaneous radioactivity is a famous example of serendipity, of how chance favors the prepared mind. Becquerel had long been interested in phosphorescence, the emission of light of one color following a body's exposure to light of another color. In early 1896, there was a wave of excitement following Wilhelm Conrad Röntgen's discovery of X-rays on the 5th of January. During the experiment, Röntgen "found that the Crookes tubes he had been using to study cathode rays emitted a new kind of invisible ray that was capable of penetrating through black paper."[9] Learning of Röntgen's discovery from earlier that year during a meeting of the French Academy of Sciences caused Becquerel to be interested, and soon "began looking for a connection between the phosphorescence he had already been investigating and the newly discovered x-rays"[9] of Röntgen, and thought that phosphorescent materials, such as some uranium salts, might emit penetrating X-ray-like radiation when illuminated by bright sunlight.

By May 1896, after other experiments involving non-phosphorescent uranium salts, he arrived at the correct explanation, namely that the penetrating radiation came from the uranium itself, without any need for excitation by an external energy source.[10] There followed a period of intense research into radioactivity, including the determination that the element thorium is also radioactive and the discovery of additional radioactive elements polonium and radium by Marie Skłodowska-Curie and her husband Pierre Curie. The intensive research of radioactivity led to Henri publishing seven papers on the subject in 1896.[5] Becquerel's other experiments allowed him to research more into radioactivity and figure out different aspects of the magnetic field when radiation is introduced into the magnetic field. "When different radioactive substances were put in the magnetic field, they deflected in different directions or not at all, showing that there were three classes of radioactivity: negative, positive, and electrically neutral."[11]

As often happens in science, radioactivity came close to being discovered nearly four decades earlier in 1857, when Abel Niépce de Saint-Victor, who was investigating photography under Michel Eugène Chevreul, observed that uranium salts emitted radiation that could darken photographic emulsions.[12][13] By 1861, Niepce de Saint-Victor realized that uranium salts produce "a radiation that is invisible to our eyes".[14] Niepce de Saint-Victor knew Edmond Becquerel, Henri Becquerel's father. In 1868, Edmond Becquerel published a book, La lumière: ses causes et ses effets (Light: Its causes and its effects). On page 50 of volume 2, Edmond noted that Niepce de Saint-Victor had observed that some objects that had been exposed to sunlight could expose photographic plates even in the dark.[15] Niepce further noted that on the one hand, the effect was diminished if an obstruction were placed between a photographic plate and the object that had been exposed to the sun, but " … d'un autre côté, l'augmentation d'effet quand la surface insolée est couverte de substances facilement altérables à la lumière, comme le nitrate d'urane … " ( ... on the other hand, the increase in the effect when the surface exposed to the sun is covered with substances that are easily altered by light, such as uranium nitrate ... ).[15]


Describing them to the French Academy of Sciences on 27 February 1896, he said:

One wraps a Lumière photographic plate with a bromide emulsion in two sheets of very thick black paper, such that the plate does not become clouded upon being exposed to the sun for a day. One places on the sheet of paper, on the outside, a slab of the phosphorescent substance, and one exposes the whole to the sun for several hours. When one then develops the photographic plate, one recognizes that the silhouette of the phosphorescent substance appears in black on the negative. If one places between the phosphorescent substance and the paper a piece of money or a metal screen pierced with a cut-out design, one sees the image of these objects appear on the negative ... One must conclude from these experiments that the phosphorescent substance in question emits rays which pass through the opaque paper and reduce silver salts.[16][17]

Becquerel in the lab
Becquerel in the lab

But further experiments led him to doubt and then abandon this hypothesis. On 2 March 1896 he reported:

I will insist particularly upon the following fact, which seems to me quite important and beyond the phenomena which one could expect to observe: The same crystalline crusts [of potassium uranyl sulfate], arranged the same way with respect to the photographic plates, in the same conditions and through the same screens, but sheltered from the excitation of incident rays and kept in darkness, still produce the same photographic images. Here is how I was led to make this observation: among the preceding experiments, some had been prepared on Wednesday the 26th and Thursday the 27th of February, and since the sun was out only intermittently on these days, I kept the apparatuses prepared and returned the cases to the darkness of a bureau drawer, leaving in place the crusts of the uranium salt. Since the sun did not come out in the following days, I developed the photographic plates on the 1st of March, expecting to find the images very weak. Instead the silhouettes appeared with great intensity ... One hypothesis which presents itself to the mind naturally enough would be to suppose that these rays, whose effects have a great similarity to the effects produced by the rays studied by M. Lenard and M. Röntgen, are invisible rays emitted by phosphorescence and persisting infinitely longer than the duration of the luminous rays emitted by these bodies. However, the present experiments, without being contrary to this hypothesis, do not warrant this conclusion. I hope that the experiments which I am pursuing at the moment will be able to bring some clarification to this new class of phenomena.[18][19]

Late career

Later in his life in 1900, Becquerel measured the properties of Beta Particles, and he realized that they had the same measurements as high speed electrons leaving the nucleus.[5][7] In 1901 Becquerel made the discovery that radioactivity could be used for medicine. Henri made this discovery when he left a piece of radium in his vest pocket and noticed that he had been burnt by it. This discovery led to the development of radiotherapy which is now used to treat cancer.[5] Becquerel did not survive much longer after his discovery of radioactivity and died on 25 August 1908, at the age of 55, in Le Croisic, France.[8] His death was caused by unknown causes, but was reported that "he had developed serious burns on his skin, likely from the handling of radioactive materials."[20]

Honors and awards

Becquerel plate
Image of Becquerel's photographic plate which has been fogged by exposure to radiation from a uranium salt. The shadow of a metal Maltese Cross placed between the plate and the uranium salt is clearly visible.

In 1889, Becquerel became a member of the Académie des Sciences.[5] In 1900, Becquerel won the Rumford Medal for his discovery of the radioactivity of uranium and he was made an Officer of the Legion of Honour.[21][8] The Berlin-Brandenburg Academy of Sciences and Humanities awarded him the Helmholtz Medal in 1901.[22] In 1903, Henri shared a Nobel Prize in Physics with Pierre Curie and Marie Curie for the discovery of spontaneous radioactivity.[8] In 1905, he was awarded the Barnard Medal by the U.S. National Academy of Sciences.[23] In 1906, Henri was elected Vice Chairman of the academy, and in 1908, the year of his death, Becquerel was elected Permanent Secretary of the Académie des Sciences.[24] During his lifetime, Becquerel was honored with membership into the Accademia dei Lincei and the Royal Academy of Berlin.[8] Becquerel was elected a Foreign Member of the Royal Society (ForMemRS) in 1908.[1] Becquerel has been honored with being the namesake of many different scientific discoveries. The SI unit for radioactivity, the becquerel (Bq), is named after him.[25] There is a crater named Becquerel on the Moon and also a crater named Becquerel on Mars.[26][27] The uranium-based mineral becquerelite was named after Henri.[28]

See also


  1. ^ a b "Fellows of the Royal Society". London: Royal Society. Archived from the original on 2015-03-16.
  2. ^ "Becquerel". Random House Webster's Unabridged Dictionary.
  3. ^ "The Discovery of Radioactivity". Berkeley Lab.
  4. ^ a b Henri Becquerel. [S.l.]: Great Neck Publishing. 2006. ISBN 9781429816434. OCLC 1002022209.
  5. ^ a b c d e Badash, Lawerence (2018). "Henri Becquerel". Encyclopædia Britannica. Retrieved 6 March 2018.
  6. ^ Karbowski, Andrzej (2012). "Biography: Henri Antoine Becquerel (1852 – 1908)" (PDF). Storytelling @ Teaching Model. Retrieved 13 April 2018.
  7. ^ a b "Henri Becquerel - Biography, Facts and Pictures". www.famousscientists.org. Retrieved 2018-03-06.
  8. ^ a b c d e f Henri Becquerel – Biographical. Nobelprize.org.
  9. ^ a b Tretkoff, Ernie (March 2008). "American Physical Society".
  10. ^ "This month in physics history March 1, 1896 Henri Becquerel discovers radioactivity". APS News. 17:3. March 2008.
  11. ^ "The Discovery of Radioactivity". Guide to the Nuclear Wallcart. 9 August 2000.
  12. ^ Niepce de Saint-Victor (1857) "Mémoire sur une nouvelle action de la lumière" (On a new action of light), Comptes rendus ... , vol. 45, pages 811–815.
  13. ^ Niepce de Saint-Victor (1858) "Deuxième mémoire sur une nouvelle action de la lumière" (Second memoir on a new action of light), Comptes rendus ... , vol. 46, pages 448–452.
  14. ^ Frog, Max. "The man who Discover the world". Retrieved 2018-04-13.
  15. ^ a b Edmond Becquerel, La lumière: ses causes et ses effets, vol. 2 (Paris, France: F. Didot, 1868), page 50.
  16. ^ Henri Becquerel (1896). "Sur les radiations émises par phosphorescence". Comptes Rendus. 122: 420–421.
  17. ^ Comptes Rendus 122: 420 (1896), translated by Carmen Giunta. Accessed 02 March 2019.
  18. ^ Henri Becquerel (1896). "Sur les radiations invisibles émises par les corps phosphorescents". Comptes Rendus. 122: 501–503.
  19. ^ Comptes Rendus 122: 501–503 (1896), translated by Carmen Giunta. Accessed 02 March 2019.
  20. ^ "Benchmarks: Henri Becquerel discovers radioactivity on February 26, 1896". EARTH Magazine. 2012-01-05. Retrieved 2018-04-13.
  21. ^ "Rumford Medal". royalsociety.org. Retrieved 2018-03-12.
  22. ^ "Henri Becquerel". www.nndb.com. Retrieved 2018-04-25.
  23. ^ "Becquerel, Henri, 1852-1908". history.aip.org. Retrieved 2018-03-12.
  24. ^ Sekiya, Masaru; Yamasaki, Michio (January 2015). "Antoine Henri Becquerel (1852–1908): a scientist who endeavored to discover natural radioactivity". Radiological Physics and Technology. 8: 1–3 – via Springer Link.
  25. ^ "BIPM - Becquerel". www.bipm.org. Retrieved 2018-04-13.
  26. ^ "Planetary Names: Crater, craters: Becquerel on Moon". planetarynames.wr.usgs.gov. Archived from the original on 27 March 2018. Retrieved 13 April 2018.
  27. ^ "Planetary Names: Crater, craters: Becquerel on Mars". planetarynames.wr.usgs.gov. Archived from the original on 14 April 2018. Retrieved 13 April 2018.
  28. ^ "Becquerelite: Becquerelite mineral information and data". www.mindat.org. Retrieved 2018-04-13.

External links

1852 in France

Events from the year 1852 in France.

1908 in France

Events from the year 1908 in France.

André-Louis Cholesky

André-Louis Cholesky (15 October 1875, Montguyon – 31 August 1918, Bagneux) was a French military officer and mathematician.

Cholesky was born in Montguyon, France. His paternal family was descendant from the Cholewski family who emigrated from Poland during the Great Emigration. He attended the Lycée in Bordeaux and entered the École Polytechnique, where Camille Jordan and Henri Becquerel taught. He worked in geodesy and map-making, and was involved in the surveying of Crete and North Africa before World War I. He is primarily remembered for the development of a matrix decomposition known as the Cholesky decomposition which he used in his surveying work.

He served in the French military as an artillery officer and was killed in battle a few months before the end of World War I; his discovery was published posthumously by his fellow officer Commandant Benoît in the Bulletin Géodésique.

Antoine César Becquerel

Antoine César Becquerel (7 March 1788 – 18 January 1878) was a French scientist and a pioneer in the study of electric and luminescent phenomena.

Barnard Medal for Meritorious Service to Science

The Barnard Medal for Meritorious Service to Science was established in 1889 by the will of Columbia University president Frederick A. P. Barnard, and has been awarded by Columbia University, based on recommendations by the National Academy of Science, every 5 years since 1895. It is not to be confused with the Barnard Medal of Distinction.


The becquerel (English: ; symbol: Bq) is the SI derived unit of radioactivity. One becquerel is defined as the activity of a quantity of radioactive material in which one nucleus decays per second. The becquerel is therefore equivalent to an inverse second, s−1. The becquerel is named after Henri Becquerel, who shared a Nobel Prize in Physics with Pierre and Marie Curie in 1903 for their work in discovering radioactivity.

Becquerel family

The Becquerel family is a family of French scientists.

The most notable members of them include:

Antoine César Becquerel (1788–1878), pioneer in the study of electric and luminescent phenomena, father of EdmondLouis Alfred Becquerel (1814-1862), French physician and medical researcher, son of Antoine Cesar, brother of Edmond

Alexandre-Edmond Becquerel (known as Edmond, 1820-1891), studied the solar spectrum, magnetism, electricity, and optics. Discovered photovoltaic effect. Son of Antoine Cesar, father of Henri.Henri Becquerel (1852-1908), discoverer of radioactivity, son of Edmond, father of JeanJean Becquerel (1878-1953), worked on the optical and magnetic properties of crystals, son of Henri


Becquerelite is a uranium mineral with the chemical formula: Ca(UO2)6O4(OH)6·8(H2O). It is a secondary mineral which contains calcium and is a bright yellow colour. It has a Mohs hardness of about 2.

It was named after the French physicist Antoine Henri Becquerel (1852–1908), who discovered radioactivity in 1896. Becquerelite contains about 70% uranium by weight.

It is mainly mined in Kasolo of the former Zaire, in the present day Democratic Republic of the Congo.

Edmond Becquerel

Alexandre-Edmond Becquerel (24 March 1820 – 11 May 1891), known as Edmond Becquerel, was a French physicist who studied the solar spectrum, magnetism, electricity and optics. He is credited with the discovery of the photovoltaic effect, the operating principle of the solar cell, in 1839. He is also known for his work in luminescence and phosphorescence. He was the son of Antoine César Becquerel and the father of Henri Becquerel, one of the discoverers of radioactivity.

Gaston Planté

Gaston Planté (22 April 1834 – 21 May 1889) was the French physicist who invented the lead–acid battery in 1859. The lead-acid battery eventually became the first rechargeable electric battery marketed for commercial use and is widely used in automobiles.

Planté was born on 22 April 1834 in Orthez, France. In 1854 he began work as an assistant lecturer in physics at the Conservatory of Arts and Crafts in Paris. In 1860 he was promoted to the post of Professor of Physics at the Polytechnic Association for the Development of Popular Instruction. An amphitheatre at that institute is named after him.

In 1855, Planté discovered the first fossils of the prehistoric flightless bird Gastornis parisiensis (named after him) near Paris. This gigantic animal was a very close relative of the famous diatrymas of North America. At that time, Planté was at the start of his academic career, serving as a teaching assistant to A. E. Becquerel (father of the Nobel laureate Henri Becquerel). This early discovery—despite causing considerable furor in 1855—was soon to be overshadowed by Planté's subsequent discoveries.

Jean Becquerel

Jean Becquerel (5 February 1878 – 4 July 1953) was a French physicist, and son of Antoine-Henri Becquerel. He worked on the optical and magnetic properties of crystals, discovering the rotation of the plane of polarisation by a magnetic field. He also published a textbook on relativity. In 1909, he became the fourth in his family to occupy the physics chair at the Muséum National d'Histoire Naturelle, following in the footsteps of his father, his grandfather A. E. Becquerel and his great-grandfather Antoine César Becquerel.

Leopold Freund

Leopold Freund (April 5, 1868 – January 7, 1943) was an Austrian-Jewish radiologist, considered the founder of medical radiology and radiotherapy.

Leopold Freund was born in Miskovice in Central Bohemia, then part of the Austro-Hungarian empire, now part of the Czech Republic. He died in Brussels in 1943.

Freund was a professor of radiology at the Medical University of Vienna and is considered the founder of medical radiology and radiotherapy. He is the first physician known to have used ionizing radiation for therapeutic purposes. In 1896, a year after the discovery of X-rays by Wilhelm Röntgen and in same year that Antoine Henri Becquerel discovered radioactivity, Freund successfully treated a five-year-old patient in Vienna suffering from hairy moles covering her whole back. The case was published by the girl's local physician, Schiff, in 1901. In 1903, he published the first textbook on radiation therapy.Freund also published fundamental work on the treatment occupational diseases with light and on the use of X-rays for testing construction materials.

Freund, who was a Jew, emigrated in 1938 to Belgium, following the annexation of Austria by Nazi Germany.

List of Fellows of the Royal Society elected in 1908

This is a list of Fellows of the Royal Society elected in 1908.

List of female Nobel laureates

As of 2018, Nobel Prizes have been awarded to 853 men, 51 women (Marie Curie won it twice), and 24 unique organizations.The distribution of female Nobel Laureates is as follows:

seventeen women have won the Nobel Peace Prize,

fourteen have won the Nobel Prize in Literature,

twelve have won the Nobel Prize in Physiology or Medicine,

five have won the Nobel Prize in Chemistry,

three have won the Nobel Prize in Physics,

and one, Elinor Ostrom, has won the Nobel Memorial Prize in Economic Sciences.The first woman to win a Nobel Prize was Marie Curie, who won the Nobel Prize in Physics in 1903 with her husband, Pierre Curie, and Henri Becquerel. Curie is also the only woman to have won multiple Nobel Prizes; in 1911, she won the Nobel Prize in Chemistry. Curie's daughter, Irène Joliot-Curie, won the Nobel Prize in Chemistry in 1935, making the two the only mother-daughter pair to have won Nobel Prizes.The most Nobel Prizes awarded to women in a single year was in 2009, when five women became laureates in four categories.

The most recent women to be awarded a Nobel Prize were Donna Strickland in Physics, Frances Arnold in Chemistry, and Nadia Murad for Peace (2018).

List of scientists whose names are used as units

Many scientists have been recognized with the assignment of their names as international units by the International Committee for Weights and Measures or as non-SI units. The International System of Units (abbreviated SI from French: Système international d'unités) is the most widely used system of units of measurement. There are seven base units and 22 derived units (excluding compound units). These units are used both in science and in commerce. Two of the base SI units and 17 of the derived units are named after scientists. 28 non-SI units are named after scientists. By this convention, their names are immortalised. As a rule, the SI units are written in lowercase letters, but symbols of units derived from the name of a person begin with a capital letter.

Marie Curie

Marie Skłodowska Curie (; French: [kyʁi]; Polish: [kʲiˈri]; 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 woman to win a Nobel Prize, the first person and only woman to win twice, and the only person to win a Nobel Prize in two different sciences. She was part of the Curie family legacy of five Nobel Prizes. She was also the first woman to become a professor at the University of Paris, and in 1995 became the first woman to be entombed on her own merits in the Panthéon in Paris.

She was born in Warsaw, in what was then the Kingdom of Poland, part of the Russian Empire. She studied at Warsaw's clandestine Flying University and began her practical scientific training in Warsaw. In 1891, aged 24, she followed her older sister Bronisława to study in Paris, where she earned her higher degrees and conducted her subsequent scientific work. She shared the 1903 Nobel Prize in Physics with her husband Pierre Curie and physicist Henri Becquerel. She won the 1911 Nobel Prize in Chemistry.

Her achievements included the development of the theory of radioactivity (a term that she coined), techniques for isolating radioactive isotopes, and the discovery of two elements, polonium and radium. Under her direction, the world's first studies into the treatment of neoplasms were conducted using radioactive isotopes. She founded the Curie Institutes in Paris and in Warsaw, which remain major centres of medical research today. During World War I she developed mobile radiography units to provide X-ray services to field hospitals.

While a French citizen, Marie Skłodowska Curie, who used both surnames, never lost her sense of Polish identity. She taught her daughters the Polish language and took them on visits to Poland. She named the first chemical element she discovered polonium, after her native country.Marie Curie died in 1934, aged 66, at a sanatorium in Sancellemoz (Haute-Savoie), France, of aplastic anemia from exposure to radiation in the course of her scientific research and in the course of her radiological work at field hospitals during World War I.

Pierre Curie

Pierre Curie (; French: [kyʁi]; 15 May 1859 – 19 April 1906) was a French physicist, a pioneer in crystallography, magnetism, piezoelectricity and radioactivity. In 1903, he received the Nobel Prize in Physics with his wife, Marie Skłodowska-Curie, and Henri Becquerel, "in recognition of the extraordinary services they have rendered by their joint researches on the radiation phenomena discovered by Professor Henri Becquerel".

Women in physics

This is a list of woman who have made an important contribution to the field of physics.

Scientists whose names are used as units
SI base units
SI derived units
Non-SI metric (cgs) units
Imperial and US customary units
Non-systematic units

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