Helium Gas
Helium gas is one of the key and widely used elements in the world, whose unique properties have given it a special position in various industries. This noble gas is the second-lightest element and one of the first to form in the universe after the Big Bang, making it a fundamental part of the composition of the cosmos. The brilliance and endless energy of the sun are also due to nuclear fusion reactions, where hydrogen is converted into helium. On the other hand, helium plays a vital role in enhancing safety in the gas industry, thanks to its non-reactivity and ability to detect gas leaks. Helium gas is considered almost harmless to human health, although precautionary measures should still be observed.
Physical and Chemical Properties
Helium gas is a colorless, odorless, and lightweight gas that is the second lightest element known after hydrogen. It is non-flammable and becomes a liquid at extremely low temperatures, approximately -269 degrees Celsius. Helium is insoluble in water and has low viscosity, allowing it to flow easily. Due to its low density, helium has the ability to lift objects in the air, making it suitable for filling balloons and airships.
Helium is an inert and highly stable element that, due to its fully filled electron shell, has no tendency to react chemically with other elements. This gas is non-toxic, non-flammable, and safe to use. Its high resistance to reactions, even under extreme temperature and pressure conditions, makes helium ideal for sensitive applications such as medical and aerospace industries. Furthermore, because of its non-reactivity, helium is one of the noble gases with extensive applications in isolated and safe environments.
Applications of Helium Gas
Gas Industry
Helium gas is used in detecting leaks in tanks and gas pipelines. Due to its small molecular size, helium can pass through cracks or leaks, making it highly efficient in leak detection tests. Additionally, helium is used in the liquefaction of natural gas (LNG) and its storage and transportation. The chemically inert nature of helium prevents any unwanted reactions between LNG and environmental gases like oxygen, thereby minimizing the risk of explosion or ignition.
Medical Applications
Liquid helium is used in MRI machines. These machines utilize superconducting components that require extremely low temperatures for optimal performance. At low temperatures, the electrical resistance of superconductors drops to zero, which is essential for generating a strong and stable magnetic field. Liquid helium, with its extremely low temperature (around -269 degrees Celsius), is used to cool these components and ensure the reliable operation of the machines.
Due to its extremely low temperature in liquid form, helium plays an important role in preserving biological samples. In biobanks and research centers, liquid helium is used to cool liquid nitrogen, which helps in the long-term preservation of sensitive samples such as stem cells, eggs, sperm, and biological tissues. The ultra-low temperature of liquid helium halts biological degradation, maintaining the quality of samples for years.
Diving
Helium is used in diving as part of gas mixtures like Trimix (helium, oxygen, and nitrogen). These mixtures are employed in deep-sea diving to reduce risks such as nitrogen narcosis and high oxygen pressure. Helium, due to its light weight and low density, makes breathing easier at high pressures. It also helps to mitigate the effects of nitrogen narcosis, thereby increasing the safety of divers at great depths.
Aerospace
Helium gas has critical applications in the aerospace industry. One of its primary uses is as a pressurizing gas in rocket fuel tanks, where helium is used to expel fuel and oxidizers without chemical reactions. Additionally, due to its cooling properties, helium is used to cool sensitive space equipment and rocket engines. Helium is also utilized in pre-launch tests, such as detecting leaks in pressurized systems or fuel tanks. Its light weight, inert nature, and ability to withstand extremely low temperatures make helium essential for enhancing safety and efficiency in space missions.
Welding
Helium is used as a shielding gas in welding to prevent hot metal from coming into contact with air. This ensures that the welded metal remains clean and free from rust or impurities. Helium also provides excellent heat transfer, generating more heat during the welding process, which is particularly useful for welding thick or tough metals like aluminum and stainless steel. Overall, helium improves welding quality and allows for deeper weld penetration.
Recreational Uses
Helium is not limited to industrial applications; it is also widely used for filling recreational balloons and party balloons. Being lighter than air and having low density, helium-filled balloons or airships naturally rise upward. Sometimes, helium is used for altering voices for entertainment purposes, though safety precautions should be observed during such activities.
Reactivity of Helium Gas
Helium, due to its electronic structure, does not exhibit chemical reactivity. Helium atoms contain only two electrons, which completely fill the first (and only) electron shell of the atom. In chemistry, atoms tend to achieve a full outer electron shell (a principle known as the “octet rule”). Since helium’s electron shell is naturally complete, the atom does not need to gain or lose electrons, and it shows no tendency to participate in chemical reactions.
Furthermore, a significant amount of energy is required to excite or alter the state of helium’s electrons. Helium’s small and simple structure (with only two protons and two neutrons in its nucleus) makes it extremely stable and devoid of any inclination to form chemical bonds with other elements. This inherent stability is the primary reason for helium’s non-reactivity, placing it among the elements that remain inert even under extreme chemical conditions.
Helium only undergoes reactions under specific conditions that exist outside Earth. In the interiors of stars, such as the Sun, where there are extraordinarily high temperatures and pressures, helium can participate in nuclear reactions. However, these reactions are not chemical but nuclear in nature.
In stars, helium is produced through the process of nuclear fusion, where hydrogen nuclei combine to form helium. This process occurs under extreme conditions, with temperatures reaching millions of degrees Celsius and immense pressures in the stellar core. Under these circumstances, hydrogen nuclei (protons) are forced close enough to each other to fuse and form helium. In older stars or in later stages of a star’s life cycle, helium nuclei can also fuse together to form heavier elements such as carbon and oxygen. These nuclear reactions release immense amounts of energy, which is the source of the light and heat emitted by stars.
Therefore, helium’s participation in reactions is limited to nuclear processes in cosmic environments and is impossible under normal Earth conditions.
Sources of Helium Gas
The primary source of helium gas is natural gas reservoirs. Helium constitutes approximately 7% by volume of natural gas. The helium present in natural gas is the result of a natural process that has occurred over millions of years underground. Heavy elements such as uranium and thorium, which exist in the Earth’s crust, undergo radioactive decay over time, producing helium in the process. This helium gradually becomes trapped in underground natural gas reservoirs.
When natural gas is extracted and processed, helium is separated and collected using methods such as fractional distillation to achieve a pure form. This process is the main method of helium extraction and the primary source of helium supply worldwide.
A very small amount of helium also exists in Earth’s atmosphere, approximately 5 ppm. However, extracting helium from air requires advanced technology and high costs. Given the extremely low concentration of helium in the atmosphere, it is not economically viable. Therefore, natural gas reservoirs remain the primary source of helium gas globally.
Is Helium Dangerous?
Helium gas, due to its lack of participation in chemical reactions, is generally considered a safe and non-hazardous gas. For this reason, it is widely used in applications such as filling balloons, airships, and in medical industries. However, caution should be exercised when inhaling helium, as pure helium can replace oxygen in the lungs. Continuous inhalation of helium instead of oxygen can cause oxygen deficiency (hypoxia), which may lead to dizziness, unconsciousness, and in severe cases, brain damage or even death.
Recreational inhalation of helium, often done to change the human voice, may seem harmless in small amounts. However, if performed repeatedly or in confined spaces, it can be dangerous. Additionally, inhaling helium from pressurized cylinders is much riskier, as the high pressure can cause serious lung injuries. Therefore, while helium is safe for most common uses, caution is necessary when inhaling it.
The helium atom, with its fully filled outer electron shell, has no tendency to react with other elements, including oxygen, which is essential for combustion. This property makes helium completely non-flammable. Unlike gases such as hydrogen or methane, which combine with oxygen and ignite, helium remains chemically stable and does not burn, even in the presence of high temperatures or ignition sources.
As mentioned earlier, the only conditions under which helium may undergo reactions are under extreme pressure and temperature, such as those found in the interiors of stars. In such extraordinary environments, nuclear fusion reactions occur, where helium nuclei can combine in nuclear processes. However, these reactions are unrelated to conventional chemical combustion and are impossible under Earth’s conditions.
Conclusion
Helium, with its unique properties such as chemical stability, lightness, and high safety, is one of the most important elements in the world. It plays a vital role in various industries, from medicine and aerospace to the gas industry. As one of the first elements formed after the beginning of the universe, helium has contributed to our understanding of the cosmos and has become an essential part of modern technologies. However, its use should be approached with care to ensure safety in its various applications.