Helium

SEO Title: Helium: Properties, Uses, Sources, Isotopes and Importance for UPSC

Category: Science & Technology | Chemistry | Natural Resources

UPSC Notes

Helium is a noble gas and the second-lightest element after hydrogen. It is chemically very unreactive because its outer electron shell is completely filled.

Key Pointers

  • Symbol: He

  • Atomic number: 2

  • Colourless, odourless and chemically inert.

  • Second-lightest element.

  • Lowest boiling point of all elements.

  • Does not readily form chemical compounds.

  • Important uses:

    • MRI/NMR cooling

    • Cryogenics

    • Leak detection

    • Semiconductor manufacturing

    • Welding

    • Balloons and airships

  • Commercial helium is mainly obtained from helium-rich natural gas deposits.

  • Helium is also produced through radioactive decay of uranium and thorium, with alpha particles eventually becoming helium atoms.

  • Important for India's space and scientific programmes.

Prelims Focus: He → atomic number 2 → noble gas → cryogenic applications.