Helium is non-polar because it is a monatomic element. This means that it exists as single atoms, not as molecules.

Here's why this makes it non-polar:

* Polarity arises from differences in electronegativity. Electronegativity is the ability of an atom to attract electrons in a bond. When two atoms with different electronegativities bond, the electrons spend more time closer to the more electronegative atom, creating a partial negative charge on that atom and a partial positive charge on the other. This difference in charge distribution leads to a polar molecule.

* Helium has only one atom. There are no bonds within a helium atom, and therefore no differences in electronegativity to create a dipole moment.

* No dipole moment means no polarity. Since there's no uneven distribution of charge within the atom, helium is considered non-polar.

In essence, helium is simply too simple to be polar. It lacks the complexity of multiple atoms bonded together to create the necessary charge separation.