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Information valid for He-4 unless otherwise noted

Basic Information

Symbol: He
Atomic Number: 2
Mass: 4.002602
Melting Point: -272.0 C
Boiling Point: -268.6 C
Number of Protons/Electrons: 2
Number of Neutrons: 2
Classification: Noble Gas
Crystal Structure: Hexagonal
Density @ 293 K: 0.1785 g/cm3
Color: colorless

Atomic Structure

[Bohr Model of Helium]
Number of Energy Levels: 1

  1. First Energy Level: 2


Isotope Half Life
He-3 Stable
He-4 Stable


Date of Discovery: 1895
Discoverer: Sir William Ramsey
Name Origin: From the Greek word hÍlios (sun)
Uses: balloons, deep sea diving
Obtained From: natural gas deposit, air