Information valid for He-4 unless otherwise noted

Helium

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

Number of Energy Levels: 1 First Energy Level: 2

Isotopes

Facts

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