Erich Armand Arthur Joseph Hückel ForMemRS[1] (August 9, 1896, Berlin – February 16, 1980, Marburg) was a German physicist and physical chemist.

[2] He is mainly known for the Debye–Hückel theory of electrolytic solutions and the Hückel method of approximate molecular orbital (MO) calculations on π electron systems.

[3] After spending 1928 and 1929 in England and Denmark, working briefly with Niels Bohr, Hückel joined the faculty of the Technische Hochschule in Stuttgart.

Pauling and Wheland characterized his approach as "cumbersome" at the time, and their competing resonance theory was relatively easier to understand for chemists without fundamental physics background, even if they couldn't grasp the concept of quantum superposition and confused it with tautomerism.

[5] The famous Hückel 4n+2 rule for determining whether ring molecules composed of C=C bonds would show aromatic properties was first stated clearly by Doering in a 1951 article on tropolone.

"Extended Hückel MO theory" (EHT) applies to both sigma and pi electrons, and has its origins in work by William Lipscomb and Roald Hoffmann for nonplanar molecules in 1962.