Neptunium's atomic number is 93 and its symbol is Np. It is is a hard, silvery, ductile, radioactive actinide metal, and can be found in 5 different colors depending on its oxidation state.

Neptunium's position in the periodic table just after uranium, named after the planet Uranus, led to it being named after Neptune, the next planet beyond Uranus. Also, it was the first trans uranium element, with an atomic mass heavier than uranium, once thought to be the heaviest element.

It is normally used to form Plutonium for spacecraft and military applications, but you may find neptunium in your smoke detector. Ionisation-type smoke detectors use tiny amounts of the radioisotope americium-241, but over time this decays into neptunium-237.

This display is contained within crystal clear lucite acrylic.

Please note that this item might be classified as hazardous material in certain countries. We suggest checking local guidelines to ensure compliance before placing your order.