Otto Hahn, {'1': ", '2': ", '3': ", '4': "} , {'1': ", '2': ", '3': 'ForMemRS', '4': "} (8 March 1879 – 28 July 1968) was a German chemist and pioneer in the fields of radioactivity and radiochemistry.
 He was exclusively awarded the Nobel Prize in Chemistry in 1944 for the discovery and the radiochemical proof of nuclear fission.
 He is referred to as the father of nuclear chemistry.
Actinide chemistry (or actinoid chemistry) is one of the main branches of nuclear chemistry that investigates the processes and molecular systems of the actinides.
 The actinides chemistry derives its name from the group 3 element actinium.
 The informal chemical symbol An is used in general discussions of actinide chemistry to refer to any actinide.
 All but one of the actinides are f-block elements, corresponding to the filling of the 5f electron shell; lawrencium, a d-block element, is also generally considered an actinide.
 In comparison with the lanthanides, also mostly f-block elements, the actinides show much more variable valence.
 The actinide series encompasses the 15 metallic chemical elements with atomic numbers from 89 to 103, actinium through lawrencium.
Chemical laws are those laws of nature relevant to chemistry.
 The most fundamental concept in chemistry is the law of conservation of mass, which states that there is no detectable change in the quantity of matter during an ordinary chemical reaction.
 Modern physics shows that it is actually energy that is conserved, and that energy and mass are related; a concept which becomes important in nuclear chemistry.
 Conservation of energy leads to the important concepts of equilibrium, thermodynamics, and kinetics.
The actinide concept in nuclear chemistry was first theorized by Glenn T. Seaborg in 1944, resulting in the extension of Dmitri Mendeleev's periodic table of the elements by placing a new actinide series, for elements 89–103, below the lanthanide series.
 In later theoretical work, Seaborg proposed the transactinide series spanning elements 104–121 and the superactinide series containing elements 122–153.
The School of Chemistry is one of the 27 academic institutions that are part of the National Autonomous University of Mexico (UNAM).
 The School carries out research activities in the fields of biochemistry, analytical chemistry, organic chemistry, physical chemistry, food chemistry, biotechnology, metallurgy, chemical engineering, pharmacy, inorganic chemistry, nuclear chemistry, theoretical chemistry and theoretical physics.
 The School is organized into 12 scientific departments and 4 units.
Larned (Larry) Brown Asprey (March 19, 1919 – March 6, 2005) was an American chemist noted for his work on actinide, lanthanide, rare-earth, and fluorine chemistry, and for his contributions to nuclear chemistry on the Manhattan Project and later at the Los Alamos National Laboratory.
Elizabeth Rona (20 March 1890 – 27 July 1981) was a Hungarian nuclear chemist, known for her work with radioactive isotopes.
 After developing an enhanced method of preparing polonium samples, she was internationally recognized as the leading expert in isotope separation and polonium preparation.
 Between 1914 and 1918, during her postdoctoral study with George de Hevesy, she developed a theory that the velocity of diffusion depended on the mass of the nuclides.
 As only a few atomic elements had been identified, her confirmation of the existence of Uranium-Y was a major contribution to nuclear chemistry.
 She was awarded the Haitinger Prize by the Austrian Academy of Sciences in 1933.
Quirino O. Navarro (born March 29, 1936) is a Filipino nuclear physicist and chemist who studied isotopes of californium, dysprosium, and einsteinium.
 His work was published in two books and three volumes and even became useful for teaching students in the University of California.
 In 1956 he graduated from the University of the Philippines with a bachelor's degree in chemistry and by 1962 he got his Ph.D. in nuclear chemistry from the University of California.
The Journal of Radioanalytical and Nuclear Chemistry is a peer-reviewed scientific journal published by Springer Science+Business Media.
 It publishes original papers, review papers, short communications and letters on nuclear chemistry.
 Some of the subjects covered are nuclear chemistry, radiation chemistry, nuclear power plant chemistry, radioanalytical chemistry, and environmental radiochemistry.
Glenn Theodore Seaborg ( ; April 19, 1912February 25, 1999) was an American chemist whose involvement in the synthesis, discovery and investigation of ten transuranium elements earned him a share of the 1951 Nobel Prize in Chemistry.
 His work in this area also led to his development of the actinide concept and the arrangement of the actinide series in the periodic table of the elements.

Question: The actinide concept in nuclear chemistry was first theorized by a chemist who won the Noble Prize in Chemistry in what year ?
Answer: 1951