Element 93
Neptunium
Actinides
Neptunium (Np) is in the f-block of the periodic table — group 3, period 7.
Neptunium is a chemical element with symbol Np and atomic number 93.
Key data
- Atomic number
- 93
- Atomic mass
- 237.000 u
- Group / Period
- 3 / 7
- Block
- f-block
- Phase at STP
- Solid
- Density
- 20.45 g/cm³
- Melting point
- 638.9 °C
- Boiling point
- 4173.9 °C
- Electron configuration
- [Rn] 5f4 6d1 7s2
Periodic table block
Neptunium is in the f-block (group 3, period 7). Elements land in the f-block when their highest-energy electrons fill an f subshell — these are the lanthanides and actinides shown beneath the main table.
New to this? Periodic table blocks explained: s, p, d, and f
Common uses
- •Neutron detectors
- •Research only
- •Radioactive
Discovery
Year: 1940
Discovered by: Edwin McMillan
Frequently asked questions
What is the atomic number of Neptunium?
Neptunium has atomic number 93. Its symbol is Np and its atomic mass is 237 u.
What category of element is Neptunium?
Neptunium is classified as actinides. It sits in group 3, period 7 of the periodic table.
What block of the periodic table is Neptunium in?
Neptunium is in the f-block (group 3, period 7). Its highest-energy electrons occupy the f subshell — you can see this in its electron configuration, [Rn] 5f4 6d1 7s2.
What is Neptunium used for?
Common uses of Neptunium include: Neutron detectors, Research only, Radioactive.
When was Neptunium discovered?
Neptunium was discovered in 1940 by Edwin McMillan.
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