(So named (
Latin Neptunus,
Neptune) by
Edwin McMillan and
Philip Abelson because it comes next to
uranium, as the planet
Neptune comes next to
Uranus) A silver-colored,
radioactive,
metallic chemical element, one of the
actinides, produced by bombarding
uranium atoms with
neutrons.
Symbol: Np
Atomic number: 93
Atomic weight: 237 (isotope with the longest known half-life)
Density (at room temperature and pressure): 20.45 g/cc
Melting point: 640°C
Boiling point: 3,902°C
Ground state electron configuration: [Rn]5f46d17s2