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Helium Gas Formula – Structure, Properties, Uses, Sample Questions

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  • Last Updated : 15 Jun, 2022
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Sir William Ramsey discovered helium in the city of London in 1895. Per Cleve and Nils Langlet independently discovered it in Sweden. Helium gets its name from the Greek word helios, which means “light.” This term literally means “Sun.” Because it was discovered near the Sun, the element was given the name Helium. In 1868, a French astronomer called Jules Janssen spotted the first evidence of Helium near the Sun. An English scientist called Edward Frankland came up with the term “helium.”

What is Helium?

Helium is a non-toxic and non-combustible element. This element is represented by He, which is also the chemical formula for Helium gas. Its atomic number is 2. It is the first noble gas in the periodic table, which means it is an inert gas. This monatomic gas has no color, odour, or taste. It was the first gas discovered in the sun and has numerous uses in diverse sectors. After hydrogen, helium is the second lightest and most common element in the universe. 

Helium is classified as an inert gas since it’s outermost electron orbital contains two electrons. Helium can also be found in lasers, compressed air tanks, and nuclear reactor coolants. Among all elements, it has the lowest boiling and melting points.  The nuclear fusion of hydrogen in stars produces a large amount of helium.

Helium is an element, which means it only has one type of atom, the helium atom. Furthermore, helium atoms have two protons each. However, changing the number of protons would result in helium being an entirely different element. Helium has an atomic number of two because each helium atom contains two protons.  

Structure of Helium


It is usually in a monatomic form. It features a 1s2 electrical configuration. The helium gas structure is a closed-packed crystal structure. Helium belongs to Period 1 of Group 18. When exposed to an electric field, it turns red-orange.  

According to the Molecular Orbital Theory, the Helium Formula is not written as He2. However, the Helium gas formula He2 is sometimes correct because, in the liquid phase, the Van Der-Waal force between them becomes dominant. At normal pressure, liquid helium does not solidify irrespective of the temperature.

Isotopes of Helium

A helium atom is made up of two protons. The number of neutrons divides between isotopes. He-3 to He-9 are the seven known isotopes of helium. Most of these isotopes have several decay schemes, with the kind of decay determined by the nucleus’ overall energy and total angular momentum quantum number.

Hence, the stable isotopes of helium are 3He and 4He. Helium-3 and helium-4 have abundances of 0.0002 percent and 99.9998 percent, respectively. The ratio of 4He to 3He atoms in the Earth’s atmosphere is about 1000000:1.

Properties of Helium Gas

Physical Properties

  1. Helium is a colorless, odourless gas that is non-combustible. In addition, helium is lighter than air. This gas is also somewhat soluble in water and chemically inert.
  2. When this gas is shipped, it is as a liquid and is extremely cold. In fact, it is so cold when it is shipped that it solidifies all other gases. Contact with this liquid helium can also cause serious frostbite. Liquid helium is used in cryogenic research as well as a nuclear reactor coolant.
  3. Helium has a boiling point of -268.928 degrees Celsius.
  4. Helium has a melting point temperature of -272.2°C.
  5. This gas is very little soluble in water, with a solubility of 0.97 mL/100 mL at 0 °C and 1.08 mL/100 mL at 50 °C.
  6. This gas is also insoluble in ethanol. Helium has a relative vapour density of 0.14 (air = 1).
  7. At 20 °C, the viscosity of this gas is 1.953. Helium has an octanol/water partition coefficient of 0.28 LogP. 

Chemical Properties

  1. The electronic configuration of Helium is 1s2.
  2. The First Ionization Energy of Helium is known to be 2372.3 kJ/mol, while the second Ionization Energy is 5250.5 kJ/mol.
  3. Vander Waals Radius of He is 140 picometers.
  4. The Enthalpy of Fusion of He is 0.0138 kJ/mol.

Uses of Helium

  • Helium is mostly used in altitude research and meteorological balloons.
  • It is also used as an inert protective gas in autogenous welding.
  • It is the only cooler capable of dropping temperatures below 15K (-434oF).
  • Helium is also involved in the manufacturing of germanium and silicon crystals.
  • Helium is used in pipeline leak detection because of its ability to permeate through solids considerably quicker than air.
  • This helium gas is also used as a carrier gas in gas chromatography.
  • Liquid helium has several uses in cryogenics, magnetic resonance imaging (MRI), and superconducting magnets due to its low melting point. 

Sample Questions

Question 1: What is the purpose of helium?


Helium gas is used to inflate blimps, research balloons, and celebratory balloons. It is used as an inert barrier for arc welding, as well as to pressurize liquid-fueled rocket fuel tanks and in supersonic wind tunnels. 

Question 2: Why is helium’s melting point so low?


As a result of the limited interaction between the noble gas atoms, they have a low boiling point. It’s worth noting that intermolecular interactions increase with atomic size, which is why helium has a lower boiling point than neon, which is preceded by argon, and so on. 

Question 3: Is helium utilized in medical applications?


Helium gas can be used to treat respiratory disorders such as asthma and emphysema. Liquid helium also has a medicinal use, as it is utilised as a cooling medium for magnets and process utilisation in MRI scanners and NMR spectrometers. 

Question 4: What Impact Does Helium Have on Human Health?


Although helium is a non-toxic gas, it has major health implications. It reduces the body’s life-sustaining oxygen levels. Excessive helium inhalation causes dizziness, vomiting, and nausea. A low oxygen concentration can cause unconsciousness and death, which can occur without warning. Because of the intake of Helium, there may be confusion and loss of judgement. It is a basic asphyxiant that reduces the body’s oxygen intake. 

Question 5: What are the main sources of Helium?


Underground resources are used to extract helium gas. However, these resources are gradually depleting. Helium cannot be produced chemically. Helium can only be produced by fusion. It consumes a lot of energy and has a high production cost. It is found as a byproduct in nuclear power plants. It is a limited resource. As a result, optimal use is critical.
Helium may be obtained from the Sun. The sun’s continual fusion and fission processes produce helium, making it the solar system’s ultimate source of energy. 

Question 6: Is helium flammable or not?


Perhaps the most well-known use of helium is as a non-flammable, safe gas for filling party and parade balloons. However, helium is an important component in many fields, including scientific research, medical technology, high-tech industry, space exploration, and national defence. 

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