Why is krypton stable? why? does krypton have any weaknesses? does krypton commonly form ions? why and why not?
does krypton have any isotopes or doppelgangers? if so, what are they and how did they form?

Krypton's atomic structure is very stable. It has just enough electrons to fill its outer 'shell', so it doesn't tend to combine with other elements. Since it doesn't combine with other elements, it doesn't take part in chemical reactions, so it will not burn, cause corrosion, or do other chemical-like things.

Explanation:

Krypton has isotopes of every mass number from 69 through 100; of these isotopes; twenty-five are radioactive and are produced by fission of uranium and by other nuclear reactions. The longest lived of these, krypton-81, has a half-life of 229,000 years.