Helium

Helium is a colorless unreactive gas that is less dense that air. It belongs to the Noble gases which is the last group on the far right of the Periodic table.

All of the Noble gases are chemically unreactive because they contain a complete number of electrons in the outer shell.

Helium gas if often used in party balloons as it is lighter than air.

Helium is also found in the sun and the stars where it is formed through a series of nuclear fusion reactions involving hydrogen.

Most of the helium used today comes from natural gas deposits in the US where it has been trapped below the surface of the Earth.