We only know they exist because of patterns in the periodic table. The interesting trend in melting and boiling points of Group 7 elements allows us to make predictions about their physical ...

Chlorine is a halogen in group VII A of the periodic table with atomic number 17, an atomic weight of 35.45, and a density of 1.56 Mg/m 3. In the solid state it forms a tretragonal crystal with a ...

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 ...