The Origin and History of Krypton

Krypton is found in the Group 18 elements, otherwise known as the Noble Gases.  In 1785, Henry Cavendish suggested that air contained nonreactive gases after he was unsuccessful in getting a sample of air to react.  A century later, British chemists John Rayleigh and William Ramsey began to isolate these inert gases (beginning with Argon) and seperated them in their own group on the periodic table since each of these elements had full electron valence shells.  One of these gases, Krypton, was discovered along with Neon and Xenon by Rayleigh and fellow chemist Morris Travers in 1898 in a residue left from evaporating almost all components of liquid air.  The name Krypton is derived from the Greek word "kryptos", meaning "hidden". However, the inert quality of these gases was disproved when Xenon compounds were created in 1962 and a Krypton compound (KrF2) was synthesized successfully a year later. This proved that this group of gases is not necessarily inert.  Although both Kr and Xe have full valence shells, they are both the most easily ionized of the group.  It simply took an element of high electronegativity, in this case Fluorine, to force Xe and Kr to react under high temperatures.