Why did Mendeleev not include plutonium in his periodic table of 1871?

1 Answer
Oct 28, 2016

For the simple reason that plutonium was unknown in the 19th century.


Plutonium, as a transuranic element, was first isolated in the 20th century, by (I think) Glenn Seaborg at Berzerkely. News of its isolation was probably delayed until long after the end of the second world war.