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.
Dickens wrote and published Great Expectations in 1860-1861, and though the novel looks back to an earlier time (1812-1840), the period of composition itself is noteworthy. England in 1860-1 was thoroughly Victorian. The Queen had been on the throne since 1837, and would reign for another 40 years.