• Protactinium - Wikipedia, the free encyclopedia

    en.wikipedia.org/wiki/Protactinium Protactinium is a chemical element with symbol Pa and atomic number 91. It is a dense, silvery-gray metal which readily reacts with oxygen, water vapor and inorganic ...
  • It's Elemental - The Element Protactinium

    education.jlab.org/itselemental/ele091.html What's in a name? From the Greek word for first, protos, and the element actinium, which together mean "the parent of actinium." Say what? Protactinium is pronounced ...
  • Protactinium - Chemicool

    www.chemicool.com/elements/protactinium.html Protactinium's properties, discovery, videos, images, states, energies, appearance and characteristics.