Metalloids : Some element have intermediate properties of the metals and non-metals. The elements which exhibit the properties of metals as well as non-metals, are called metalloids.
Example : Boron, Silicon, Germanium etc.
NOBLE GASES:
These elements are found in air in the form of gas in very small amounts.Hence they are called as Rare gases. They are monoatomic in nature.These elements do not react chemically with other elements, so these are also called as Noble gases.
Ex: Helium,Neon,Argon ,Krypton, Xenon and Radon.
NOTE:* Helium is second lightest element after hydrogen.
* Radon is radioactive element.