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 ...

Xenon is an inert gas in group VIII A of the periodic table with atomic number 54, an atomic weight of 131.3, and a density of 3.06 Mg/m 3. In the solid state it forms an fcc crystal with a melting ...

The earliest attempt to classify the elements was in 1789, when Antoine Lavoisier grouped the elements based on their properties into gases ... the diagram of the periodic table above separates ...

It was debated whether the 'inert' monoatomic gases belonged to the periodic table owing to their lack of 'chemical properties'; elements coming late to the party, with no unpaired electrons to ...