In the past 250 years, new elements have been added to the table about once every 2 ½ years on average, said Paul Karol of Carnegie Mellon University. He chaired the committee that recognized the ...

Oganesson, for example, was created by colliding atoms of californium (atomic number 98) and calcium (20). Over several years, the fleeting existence of only a handful of oganesson atoms was recorded.

Every element in the periodic table gives off a certain amount of visible light. It’s this light that makes it easy to tell gold (Au) and silver (Ag) apart.