Students learn to describe the pattern in atomic number, atomic mass and atomic radius. Trends on the Periodic Table: Students learn to describe the pattern in atomic number, atomic mass, atomic ...

In this video excerpt from NOVA's "Hunting the Elements," New York Times technology columnist David Pogue explores how the periodic table of elements took shape. Learn how the periodic table developed ...

The covalent radius (a measure of how large individual atoms are) shows different trends if you are moving across a period or down a group. A comparison of the relative covalent radii of atoms is ...

The news broke that a railroad car, loaded with pure sodium, had just derailed and was spilling its contents. A television reporter called me for an explanation of why firefighters were not allowed to ...

For now, they're known by working names, like ununseptium and ununtrium — two of the four new chemical elements whose discovery has been officially verified. The elements with atomic numbers 113, 115, ...