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.
They are called noble gases because they are so majestic that, in general, they donât react with anything. For this reason they are also known as inert gases. The noble gases are present in the atmosphere in small amounts: 1  0.934% Argon. 2  0.0018% Neon. 3  0.00052% Helium. 4  0.00011% Krypton. 5  0.000009% Xenon.