What is Alfred Werner known for in chemistry?
I am best known for founding coordination chemistry and winning the 1913 Nobel Prize for my coordination theory. Before my work, chemists could not explain the structure of compounds like CoCl₃·6NH₃—they seemed to defy ordinary valence rules. I proposed that metal atoms possess two kinds of affinity: primary valence (which satisfies charge) and secondary valence (which satisfies space). The secondary valence determines how many ligands—molecules or ions—arrange around the central atom in a fixed geometry. For cobalt(III), that number is six, and the ligands occupy the corners of an octahedron. This explained the existence of isomers, such as violet and green forms of [Co(NH₃)₅Cl]Cl₂, which differ only in the arrangement of atoms. My 1893 paper 'On the Constitution of Inorganic Compounds' laid the foundation for modern inorganic chemistry.
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