Chemistry Tuition: About Helium

Helium (He), the second lightest element and a noble gas, is the second most abundant element in the universe after hydrogen. While many students know it for balloons, helium plays a much larger role in science and technology.

Discovery and History of Helium

Helium was first discovered in the sun before Earth.

• 1868 – French astronomer Pierre Janssen and British astronomer Norman Lockyer observed a yellow spectral line during a solar eclipse that did not match any known element. They named it helium, after Helios, the Greek god of the sun.
  
• 1895 – Scottish chemist Sir William Ramsay isolated helium on Earth from the mineral cleveite, confirming its existence.
  

By the 20th century, helium became vital in science and war technology.

• World War I – Used in airships as a safer alternative to flammable hydrogen.
  
• Mid-20th century – Found widespread use in cryogenics, medical technology, and research.
  

Chemical Properties of Helium

Helium belongs to Group 18 (noble gases). It is a noble gas with the chemical symbol He and atomic number 2. 

Its atomic structure consists of two protons and two electrons, with usually two neutrons in the nucleus (for the common isotope, helium-4). Unlike most elements, helium is monatomic in its natural state, existing as single atoms rather than molecules, and it is completely inert under normal conditions because its outer electron shell is full. This gives helium very limited chemical composition in the traditional sense—it does not normally form stable compounds.

This chemical stability explains why helium is preferred in environments where reactivity must be avoided.

Physical Properties of Helium

Helium’s physical traits make it unique and useful:

• Boiling point: –269 °C → remains a gas even near absolute zero.
  
• Cryogenics: Used in cooling superconducting magnets for MRI machines and particle accelerators.
  
• Low density: Lighter than air → used in balloons and airships.
  
• Breathing mixtures: In deep-sea diving, helium reduces risks of nitrogen narcosis and oxygen toxicity.
  
• Superfluidity: Helium-4 becomes a superfluid near absolute zero → flows without friction. This property is important in quantum mechanics research.
  

Where is helium tested in O Level Chemistry and A Level Chemistry 

O Level Chemistry

In O Level Chemistry, helium is usually tested in the context of the noble gases (Group 18). Students are expected to know its structure and properties such as low boiling point, and uses such as in balloons, airships, and as a protective gas in welding. 

Questions often focus on comparing helium with other noble gases in terms of stability and applications rather than chemical reactions, since helium does not readily form compounds.

A Level Chemistry

In A Level Chemistry, helium may appear when discussing periodicity and ionisation energy trends across the periodic table. Its very high first ionisation energy is used as an example of how atomic structure influences chemical properties. 

It may also be mentioned in the context of low-temperature physics and cryogenics due to its extremely low boiling point. However, it is not a major element tested for chemical reactivity, but rather for illustrating principles of atomic structure, periodic trends, and the applications of noble gases.

Future of Helium Resources

Helium is mostly extracted from natural gas deposits, but reserves are limited. This raises concerns about sustainability.

Solutions being explored:

• Recycling technology – Recovering helium from cryogenic and industrial processes (e.g. MRI machines).
  
• Atmospheric extraction – Present but costly. May become viable with new technology.
  
• Extraterrestrial sources – The moon is believed to contain helium-3, a potential future energy resource.