The 13 elements that are room temperature gases are radon (Rn), xenon (Xe), krypton (Kr), argon (Ar), chlorine (Cl), neon (Ne), fluorine (F), oxygen (O), nitrogen (N), helium (He) and hydrogen (H). Most non-metals in the periodic table have a gaseous elemental form.
Fluorine, oxygen, chlorine, nitrogen and hydrogen are found as diatomic molecules. Radon, helium, xenon, neon, krypton and argon are eight noble gases. They are nonreactive, mono-atomic elements with extremely low boiling points. Each of the 13 elements has their own unique physical and chemical properties. Mercury (Hg) and bromine (Br) are the only elements in the periodic table that are liquids at room temperature.