He-4 (Helium-4)

Helium-4 is a stable isotope of helium, consisting of two protons and two neutrons in its nucleus. It is a colorless, odorless, and inert gas known for its very low boiling point, making it ideal for cooling applications like MRI machines and scientific instruments. Helium-4 is naturally produced through the radioactive decay of heavier elements. It is also the primary component of natural helium gas found underground. Its unique quantum properties cause it to become a superfluid at extremely low temperatures, enabling it to flow without friction and climb walls—a phenomenon that highlights its fascinating quantum behavior.