Hahn, Otto (1879–1968) GermanChemist Otto
Hahn was born on March, 8, 1879, in Frankfurt-on-
Main and attended and graduated from the city’s sec-
ondary high school. In 1897 he began studying
chemistry at Marburg and Munich, receiving a doc-
torate in 1901 at Marburg for a thesis on organic
chemistry.
He became assistant in the Chemical Institute at
Marburg for two years, and in 1904 moved on to Uni-
versity College, London, working under Sir William
Ramsay. Here he discovered a new radioactive sub-
stance, radiothorium, while working on the prepara-
tion of pure radium salts.
From 1905 to 1906, he worked at the Physical
Institute of McGill University, Montreal (Canada), and
discovered radioactinium and conducted investigations
with Rutherford on alpha rays of radiothorium and
radioactinium.
Hahn moved to Berlin, to the Chemical Institute of
the University, as a university lecturer in the spring of
1907 and discovered mesothorium. At the end of 1907,
Hahn began a 30-year collaboration with Dr. Lise
Meitner, who came to Berlin from Vienna. They
worked on investigations on beta rays, discovered pro-
tactinium, and Hahn discovered the fission of uranium
and thorium. In 1944 he was awarded the Nobel Prize
in chemistry “for his discovery of the fission of heavy
nuclei.”
He died on July 28, 1968, in Gottingen, West Ger-
many, after a fall.half-cell Compartment or location (single elec-
trode) in an electrolytic cell or voltaic cell in which
the oxidation or reduction half-reaction occurs. It is
oxidation at the anode, reduction at the cathode. A
half-cell reaction refers to the chemical equation that
describes only the oxidation or reduction part of a
redox reaction.half-life For a given reaction, the half-life (t1/2) of a
reactant is the time required for its concentration to
reach a value that is the arithmetic mean of its initial
and final (equilibrium) value. For a reactant that is
entirely consumed, it is the time taken for the reactant
concentration to fall to one-half of its initial value. For
a first-order reaction, the half-life of the reactant may
be called the half-life of the reaction. In nuclear chem-
istry, (radioactive) half-life is defined, for a simple122 Hahn, Otto
Haber process. An industrial process for the catalyzed production
of ammonia from N 2 and H 2 at high temperature and pressure
Half-cell. Compartment or location (single electrode) in an elec-
trolytic cell or voltaic cell in which the oxidation or reduction
half-reaction occurs