Generally, the more empty the outer electron shell, the more reactive the element. Helium has two(2) electrons, and is thus full, all the other noble elements has eight(8) electrons in it's outer electron shell, so they are also full. *And for everyone's sake, krypton is not green, but colorless, and forms white crystals when solid.
(a) Jubilees was written between 153 B.C. and the year of Hyrcanus' breach with the Pharisees. (1) It was written during the pontificate of the Maccabean family, and not earlier than 155 B.C., when this office was assumed by Jonathan the Maccabee.
Kings was written between 561â538 B.C. Since the last narrated event (2 Kin. 25:27â30) sets the earliest possible date of completion and because there is no record of the end of the Babylonian captivity in Kings, the release from exile (538 B.C.) identifies the latest possible writing date.