OPOpenPithMake curiosity visibleCHEMISTRY LAB / 02

The Periodic Table

118 elements, raised by their properties.

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About Neptunium

Neptunium 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.

The text above is from the lead of the Wikipedia article “Neptunium” (retrieved 2026-11-05), used under CC BY-SA 4.0. Read on Wikipedia · CC BY-SA 4.0

Data and notes

Column height is a linear display mapping; the shortest column is not zero. Data: PubChem, IAEA.

Solid columns are measured, frosted glass is predicted, empty frames have no value.

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