Physicists have filled in some longtime blank spaces on the periodic table, calculating electron affinities of the lanthanides, a series of 15 elements known as rare earths. Physicists at Michigan ...

A few of our favorites are on these pages. And the table is still ... Mendeleev left blank spaces in his original periodic table so that he could properly line up the known elements.

When Mendeleev introduced his periodic table, he predicted that when new chemical elements were discovered, they would fill his table’s blank spots ... “More than half of these exceptions ...

Generally for the elements after uranium, the further along they are on the periodic table — the higher their atomic number — the less time they last. Half-lives of unstable elements vary by ...