1. Chemistry(Material Noun-Neuter) A chemical element with symbol Np and atomic number 93. A radioactive actinide metal, neptunium is the first transuranic element. এক তেজস্কিয় মৌল৷ পাৰমাণবিক সংখ্যা ৯৩৷ প্ৰথমটো ইউৰেনিয়াম উত্তৰ মৌল৷

2. ChemistryNeptunium is a chemical element; it has symbol Np and atomic number 93. A radioactive actinide metal, neptunium is the first transuranic element. It is named after Neptune, the planet beyond Uranus in the Solar System, which uranium is named after. A neptunium atom has 93 protons and 93 electrons, of which seven are valence electrons. Neptunium metal is silvery and tarnishes when exposed to air. The element occurs in three allotropic forms and it normally exhibits five oxidation states, ranging from +3 to +7. Like all actinides, it is radioactive, poisonous, pyrophoric, and capable of accumulating in bones, which makes the handling of neptunium dangerous. Although many false claims of its discovery were made over the years, the element was first synthesized by Edwin McMillan and Philip H. Abelson at the Berkeley Radiation Laboratory in 1940. Since then, most neptunium has been and still is produced by neutron irradiation of uranium in nuclear reactors. The vast majority is generated as... from wikipedia.org