What is the smallest unit of Helium that still maintains all of the same characteristics of Helium?

The smallest unit of helium that retains all its characteristics is a helium atom. A helium atom consists of two protons, two neutrons, and two electrons, which together define its chemical properties and behavior. When helium is in its elemental form, it exists as a monoatomic gas, meaning each atom functions independently while still exhibiting the characteristics of helium, such as being non-reactive and having a low density.