Argon is an inert gas in group VIII A of the periodic table with atomic number 18, an atomic weight of 39.948, and a density of 1.40 Mg/m 3. In the solid state it forms an fcc crystal with a melting ...

There are currently 118 known elements on the periodic table, and we've put 20 of them ... Do you know what element Ar is? Ar ...

The noble gases (Helium, Neon, Argon etc.) were not discovered until ... and produced several Periodic Tables between 1864-1870. His first table contained just 28 elements, organised by their valency ...

Players read questions about energy levels and score points by picking the correct element as the answer ... 3rd Period: Sodium to argon—Electrons go into the third energy level. After the third ...

In 1869, Mendeleev's first periodic table did not include them, as closed-shell elements remained undiscovered until Lord Rayleigh and William Ramsey isolated argon in 1894. Remarkably ...