Krypton

Krypton is a chemical element, having the chemical symbol Kr.

Krypton 83.798(2)   Kr 36 [Ar] 4s2 3d10 4p6 [ ? ] Noble gas:

Its atomic number (the number of protons) is 36. It has a Standard Atomic Weight of 83.798(2), and is typically found as a gas in its elemental form.

Krypton is considered to be a member of the "Noble gas" class of elements, has a boiling point of -153.22 °C , and a melting point of -157.38 °C .

The isotope ⁸⁵Kr is emitted by the process of producing plutonium, and air sampling for it, as well as for ¹³³Xenon, is used in Materials MASINT and national technical means of verification as a way to remotely monitor such facilities. It is also released by atmospheric nuclear explosions.