protium

The most abundant isotope of hydrogen, H-1, having one proton in the nucleus.

A genus of polypetalous trees of the order Burseraceæ and tribe Bursereæ.

The lightest and most common isotope of hydrogen, having a single proton and no neutrons – 11H

An atom of this isotope.

genus of chiefly tropical American trees having fragrant wood and yielding gum elemi