History of the Periodic Table: Mendeleev Left Gaps and They Turned Out to Be Real
In 1869 a Russian chemist named Dmitri Mendeleev left gaps in his table of elements and announced that undiscovered elements belonged in them. He predicted their atomic weights, densities, and melting points. When gallium was found in 1875 and germanium in 1886, both matched his numbers closely. That is the moment the periodic table stopped … Read more
