Helium is the chemical element with the symbol He and atomic number 2. It is a colorless, odorless, and tasteless noble gas that is lighter than air. Helium is the second lightest element in the universe, after hydrogen, and is the second most abundant element in the universe overall.

Key Characteristics of Helium:

1. Atomic Structure: Helium consists of two protons, two neutrons, and two electrons. It has the simplest atomic structure among all elements and is a member of the noble gas group on the periodic table.
2. Abundance and Occurrence: Helium is the second most abundant element in the universe, primarily formed through nuclear fusion in stars. However, helium is relatively rare on Earth’s surface. It is often found in natural gas deposits, where it is extracted as a byproduct during natural gas production.
3. Low Density and Inertness: Helium is a very light gas and is less dense than air. As a result, it is commonly used to fill balloons and airships to make them float. Helium is also chemically inert, meaning it does not readily react with other substances under normal conditions.
4. Low Boiling Point: Helium has an extremely low boiling point of -268.93 degrees Celsius (-452 degrees Fahrenheit), which is close to absolute zero. This property allows helium to be used in various applications that require low-temperature environments, such as cryogenics and superconductivity research.
5. Applications: Helium has several practical applications. One of the most well-known uses is filling balloons and blimps for festive events and scientific research. Helium is also used in cryogenics for cooling superconducting magnets in MRI machines, as a shielding gas in welding, and in various scientific and industrial processes.
6. Liquid Helium: When helium is cooled below its boiling point, it becomes a liquid. Liquid helium is used in cryogenic research, low-temperature experiments, and cooling applications where extremely low temperatures are required.

Helium is an important element in scientific research, industry, and various technological applications. Due to its limited availability and high demand, there are concerns about the long-term sustainability of helium supplies. Efforts are being made to promote helium recycling and develop more efficient helium extraction methods to ensure its availability for future applications.