Category: Noble gas
Atomic Number: 2
Period: 1 | Group: 18
Block: s-block
Inert, weightless and permanently escaping: helium is the only element that will not freeze at ordinary pressure, no matter how cold you make it.
| Property | Value |
|---|---|
| Phase at STP | Gas |
| Density | 0.00017848 g/cm³ |
| Melting Point | 0.95 K (-272.20 °C) |
| Boiling Point | 4.22 K (-268.93 °C) |
| Heat Capacity | N/A |
| Property | Value |
|---|---|
| Atomic Mass | 4.0026 u |
| Electronegativity (Pauling) | N/A |
| Oxidation States | 0 |
| Electron Configuration | 1s² |
| Discovered By | Pierre Janssen & Norman Lockyer |
|---|---|
| Discovery Year | 1868 |
| Named After | Greek helios, the Sun — found there before Earth |
| ISOTOPE | Neutrons | Natural Abundance | Half-life | Decay Mode |
|---|---|---|---|---|
| He-3 | 1 | 0.0002% | Stable | - |
| He-4 | 2 | 99.9998% | Stable | - |
Data: IAEA Nuclear Data Section, LiveChart of Nuclides, ground-state evaluations, retrieved October 10, 2026. Abundance is the share of atoms in the natural element; a dash means the isotope has no standard natural abundance.
High-Tech Applications & Uses
🎈 Consumer & Entertainment
Party Balloons : Provides lift due to density 7 times less than air
Voice Alteration : Inhaling helium raises the resonant frequencies of the vocal tract (the vocal cords keep the same pitch), creating high-pitched voice (Note: Can be dangerous - can cause asphyxiation)
Airships & Blimps : Goodyear blimps use 200,000+ cubic feet of helium for safe, non-flammable lift
🧪 Scientific & Medical Applications
MRI Magnets : Cools superconducting magnets to 4.2K (-269°C) - each MRI machine requires 1,500-1,700 liters
Breathing Mixtures : Heliox (80% helium, 20% oxygen) treats severe asthma and decompression sickness
Deep Sea Diving : Trimix (helium, nitrogen, oxygen) prevents nitrogen narcosis at depths >30 meters
Leak Detection : Helium's small atomic size makes it ideal for finding tiny leaks in vacuum systems and pipelines
Chromatography : Carrier gas in gas chromatography due to chemical inertness and thermal conductivity
🚀 Aerospace & Technology
Rocket Engine Cooling : SpaceX Falcon 9 uses helium to pressurize its propellant tanks (its Merlin engines are cooled by their own kerosene fuel)
Satellite Attitude Control : Cold gas thrusters use pressurized helium for precise spacecraft maneuvering
Telescope Cooling : James Webb Space Telescope MIRI instrument cooled to about 7K by a helium-gas cryocooler (Webb carries no liquid helium) for infrared detection
Semiconductor Manufacturing : Creates inert atmosphere during silicon chip production and ion implantation
🔬 Research Applications
Particle Accelerators : Large Hadron Collider uses 130 tons of liquid helium to cool superconducting magnets
Nuclear Research : Helium-3 for neutron detection and potential fusion reactors
Cryogenics Research : Achieving temperatures near absolute zero for quantum experiments
Sources & Natural Occurrence
🌍 Terrestrial Sources
Despite being abundant in the universe, helium is extremely rare on Earth (5.2 ppm in atmosphere) because its light weight allows it to escape Earth's gravity. Most terrestrial helium forms through radioactive decay:
Underground Natural Gas Deposits
Alpha Decay Process : Uranium and thorium decay releases alpha particles (helium nuclei)
Accumulation : Over millions of years, helium accumulates in natural gas reservoirs
Concentration : Economic extraction requires >0.3% helium in natural gas
Major Fields : Texas Panhandle, Kansas, Algeria, Qatar, and Russia
Atmospheric Helium
Primordial Origin : Residual from Earth's formation
Cosmic Ray Production : High-energy particles create helium-3 in upper atmosphere
Solar Wind : Helium-3 deposited on lunar surface by solar wind
🏭 Commercial Production
Fractional Distillation of Natural Gas
Process : Cool natural gas to -180°C, separate by boiling points
Purification : Multiple distillation stages achieve 99.99% purity
Global Production : ~180 million cubic meters annually
Major Producers : United States (75%), Qatar (10%), Algeria (8%)
Strategic Reserve
US Federal Helium Reserve : Amarillo, Texas - world's largest helium storage
Capacity : 24.2 billion cubic feet in underground salt domes
Purpose : Strategic supply for defense and scientific applications
🌌 Cosmic Abundance
In the universe, helium forms through Big Bang nucleosynthesis (25% of normal matter) and ongoing stellar fusion. Stars fuse hydrogen into helium via the proton-proton chain, with our sun converting 600 million tons of hydrogen to helium every second. Helium-3, abundant on the Moon from solar wind deposition, represents a potential future fusion fuel source.
| Earth's Crust | 0.0000005200 ppm |
|---|---|
| Universe | 0.2300000000 % |