Helium

Helium 4.002602(2)   He 2 1s2 [ ? ] Noble gas: Properties: Inert, colorless, odorless, non-toxic gas

Helium is a chemical element, having the chemical symbol He. Its atomic number (the number of protons) is 2. It has a standard atomic weight of 4.002602, and is typically found as a gas in its elemental form.

Helium is considered to be a member of the "Noble gas" class of element. At a pressure of 101.325 kPa, it has a boiling point of -268.93 °C, and a melting point of -272.2 °C.