Medical Definition of PNEUMOTAXIC CENTER. : a neural center in the upper part of the pons that provides inhibitory impulses on inspiration and thereby prevents overdistension of the lungs and helps to maintain alternately recurrent inspiration and expiration. a neural center in the upper part of the pons that provides inhibitory impulses on inspiration and thereby prevents overdistension of the lungs and helps to maintain alternately recurrent inspiration and expiration.
Because of their uber-high stability, the noble gases are relatively unreactive. They have very high ionization energies and negligible electronegativities because they have no desire to gain or lose an electron.
The most important chemical property of the noble gases is their lack of reactivity. Helium, neon, and argon do not combine with any other elements to form compounds. It has been only in the last few decades that compounds of the other rare gases have been prepared. In 1962 English chemist Neil Bartlett (1932â) succeeded in preparing the first compound of a noble gas, a compound of xenon.