The Noble Gasses are generally chemically inert, meaning that they normally do not react with the other elements because they have their desired amount of 8 S and P Electrons.
These gasses weren't discovered until the last 5 years of the 1800's because they are rare in nature.
Nothing was known about Helium until it was discovered to exist on the Sun. The name Helium comes from the Greek word Helios, which means Sun.