Friedrich Hermann Hund (4 February 1896 - 31 March 1997) was a German physicist from Karlsruhe known for his work on atoms and molecules.

Hund worked at the Universities of Rostock, Leipzig, Jena, Frankfurt am Main, and Göttingen. Hund worked with such prestigious physicists as Schrödinger, Dirac, Heisenberg, Max Born, and Walter Bothe. At that time, he was Born's assistant, working with quantum interpretation of band spectra of diatomic molecules.

After his studies of mathematics, physics, and geography in Marburg and Göttingen, he worked as a private lecturer for theoretical physics in Göttingen (1925), professor in Rostock (1927), Leipzig (1929), Jena (1946), Frankfurt/Main (1951) and from 1957 again in Göttingen. Additionally, he stayed in Copenhagen (1926) with Niels Bohr and lectured on the atom at Harvard University in Cambridge, Massachusetts (1928). He published more than 250 papers and essays in total. Hund made pivotal contributions to quantum theory - especially concerning the structure of the atom and of molecular spectra.

In fact, Robert S. Mulliken, who was awarded the 1966 Nobel Prize in chemistry for molecular orbital theory, always proclaimed the great influence Hund's work had on his own and that he would have gladly shared the Nobel prize with Hund. In recognition of the importance of Hund's contributions, MO theory is often referred to as the Hund - Mulliken MO theory. Hund's rule [of maximum multiplicity] is another eponym and, in 1926, Hund discovered the so-called tunnel effect or quantum tunnelling.

The Hund's cases, which are particular regimes in molecular angular momentum coupling, and the Hund's rules, which govern electron configurations, are important in spectroscopy and quantum chemistry. In chemistry, the first of Hund's rules is especially important and is often referred to as simply Hund's Rule.

On the occasion of his 100th birthday, the book: Friedrich Hund: Geschichte der physikalischen Begriffe [History of Physical Concepts] (Heidelberg, Berlin, Oxford), Spektrum, Akademie Verlag 1996, was published. A review was also written by Werner Kutzelnigg.

Besides many different honors bestowed upon him, Friedrich Hund became an honorary citizen of Jena/Saale, and a street in Jena was named after him. Since June, 2004, a part of the new building of the Physics Department was given the Friedrich - Hund - Platz 1 address. The same name was chosen for the Institute for Theoretical Physics at the University of Göttingen. He was a member of the International Academy of Quantum Molecular Science.