Johannes Nicolaus Brønsted

Johannes Nicolaus Brønsted (; 22 February 1879 – 17 December 1947) was a Danish physical chemist who is best known for developing the Brønsted–Lowry acid–base theory; he developed the theory at the same time as (but independently of) Martin Lowry.

Biography Brønsted was born in Varde, Denmark on 22 February 1879. His mother died shortly after his birth, and his father died when Brønsted was 14 years old; he then moved to Copenhagen with his older sister and his stepmother. In 1897, Brønsted began his studies as a chemical engineer at the Polytechnic Institute in Copenhagen. After his first degree, Brønsted changed fields and received his magister degree in chemistry in 1902 from the University of Copenhagen. In 1905, he became an assistant at the Chemical Institute and obtained his doctoral degree in 1908. In the same year, Brønsted became a professor of physical and inorganic chemistry at the University of Copenhagen. His research gained worldwide recognition, resulting in four Nobel Prize nominations, a gold H. C. Ørsted Medal and being appointed as a fellow of the Royal Society and a member of the National Academy of Sciences.

Brønsted married Charlotte Warberg, whom he met during his first degree. The couple had four children. In World War II, Brønsted's opposition to the Nazis led to his election to the Danish parliament in 1947, but he was too ill to take his seat and died shortly after the election.

Brønsted is best known for his work on reaction kinetics, in particular acid–base reactions. In 1923, he recognized that acid–base reactions involved the transfer of a proton, from the acid (proton donor) to the base (proton acceptor). Almost simultaneously and independently, the British chemist Martin Lowry arrived at the same conclusion, thus the name Brønsted–Lowry acid–base theory. Also in 1923, Gilbert N. Lewis proposed an electronic theory of acid–base reactions, but both theories remain commonly used.