Helium is a chemical element with symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas that heads the noble gas group in the periodic table. It’s boiling and melting points are the lowest among all the elements. Helium is the second least reactive noble gas, after neon, and thus the second least reactive of all elements. It is inert and monatomic in all standard conditions. Since, helium has relatively low molar (atomic) mass, its thermal conductivity, specific heat, and sound speed in the gas phase are all greater than any other gas except hydrogen.

Helium is a chemical element with symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas that heads the noble gas group in the periodic table. It’s boiling and melting points are the lowest among all the elements. Helium is the second least reactive noble gas, after neon, and thus the second least reactive of all elements. It is inert and monatomic in all standard conditions. Since, helium has relatively low molar (atomic) mass, its thermal conductivity, specific heat, and sound speed in the gas phase are all greater than any other gas except hydrogen.