Predicting the Atomic Weights of the Trans-Lawrencium Elements:A Novel Application of Dobereiner's Triads

摘要

In 1829,Johann Wolfgang Dobreiner (1780-1849) reported that some elements may be grouped into triads,groups of three elements that show a smooth,gradual process in properties and also possess a special arithmetical relationship:the atomic weight of the second member in a given triad is almost exactly the mean of the atomic weights of the first and third member (1).Dobereiner's early bold assertion was doomed to fail as not enough elements were then known and also because of the fact that most of the known elements could not be fitted into recognizable triads.