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 ...

Mendeleev left several spaces blank in his table, and he made the bold guess that someday new elements would be discovered that would fill those blanks. Countless revisions of the table followed ...

The Periodic Table of Elements. Each entry contains the atomic number, chemical symbol, and atomic mass to two decimal places on elements where data is available. Undefined cells contain a space. Row ...