atomic number

Thus, they exposed the secrets of this extremely rare lanthanide, whose atomic number is 61, in a series of meticulous experiments.

In HAADF-STEM images, signal intensity correlates with the square of the atomic number, making it particularly useful for analyzing heavy elements.

Lighter elements -- generally those with an atomic number of 20 or lower on the periodic table -- often have an equal number of protons and neutrons.

And for the individual metals the team could detect, the star also displayed sharply differing abundances for elements with odd and even atomic numbers—a telltale sign of a pair-instability supernova.

Katie Hafner: Uranium is the last of the naturally occurring elements on the periodic table, with an atomic number of 92.