Whose discovery showed why lithium, sodium, and potassium form a natural family?

Lothar Meyer independently developed an early version of the periodic table in the 1860s and demonstrated the repeating pattern of chemical properties across the elements. In that pattern, lithium, sodium, and potassium appear together because they share one valence electron and similar reactivity. Mendeleev’s table became more famous, but Meyer’s work was important in showing that element properties are periodic. The alkali metals are among the clearest examples of a family defined by the periodic table.