He
Helium (Atomic Number 2)
Category: noble | Period 1, Group 18 | Block: s
Second lightest element, highly unreactive noble gas.
Atomic & Physical Constants
- Standard Atomic Weight:
- 4.002602 u
- Standard State Phase:
- Gas
- Electron Configuration:
- 2
- Electronegativity (Pauling):
- N/A
- Melting Point:
- 0.95 K
- Boiling Point:
- 4.222 K
Historical Discovery & Real-World Applications
Industrial & Scientific Uses
Balloons, deep-sea diving, supercooling NMR magnets
Discovery History
Discovered by Pierre Janssen (1868).
Study Helium with Socratic AI Tutor
Get step-by-step orbital hybridization, oxidation state derivations, and reaction practice questions.