Logical connectives in science: A summary of the findings

Hydrogen stands alone among the elements of the periodic system. Its single electron might make feasible its classification with the alkali metals but hydrogen does not lose its electron easily enough to warrant such classification. Similarly, hydrogen has at times been classified with the halogen elements because it needs only one more electron to satisfy the rare-gas electron arrangement of helium. In any case, trying to classify hydrogen as an alkali metal or as a halogen would only be “forcing” such a classification; for this reason, hydrogen will be considered unique among the elements, constituting a “family” in itself. Nechamkin (1968, p. 1)