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.
The series was originally published in English by two major publishers, Bloomsbury in the United Kingdom and Scholastic Press in the United States. A play, Harry Potter and the Cursed Child, based on a story co-written by Rowling, premiered in London on 30 July 2016 at the Palace Theatre, and its script was published by Little, Brown.