-Hydrogen (H), a colourless, odourless, tasteless, flammable gaseous substance that is the simplest member of the family of chemical elements. - Helium is a chemical element with symbol He and atomic number 2. -Nitrogen is an element, not a compound. It is found in nature as nitrogen gas, also called dinitrogen, with the chemical formula N2 , and makes up 78% of the atmosphere.
