Helium is the second lightest chemical element on the periodic scale of the elements, and the most abundant in the universe. Its atomic number is 2, and its atomic mass is 4,003 amu (Atomic Mass Units).

Helium is an inert element, that is, it does not react to most other chemical elements. It does not combine with other elements, and is stable at room temperature and pressure, except for extreme conditions. It has no odor or taste, and is transparent to visible light.

Helium is very light and has a melting point of -452.2°F (-268.9°C). Its boiling point is the highest of all the elements, at -452.1°F (-268.9°C). It is also very unreactive and does not combine with other elements, which makes it an excellent thermal insulator and an inert gas to protect other flammable gases.

Helium is used in many industries, including cooling, beacon systems, and medicine. It is also used to fill balloons and hot air dirigibles. It is also used in the manufacture of fiber optics, for lighting and personal safety. Finally, it is used for filling the exhaust gases of combustion engines, in order to reduce carbon emissions.

4.002602

1s2

24.5874

Synthetic

Radioactive

Liquid

Gaseous

Electronic configuration diagram

Characteristics

Name	Helium
Number	2
Atomic	4.002602
Symbol	He
Fusion	-272.2
Boiling	-268.9
Density	0.0001785
Period	1
Group	18

Discovery	1868 Janssen
Abundance	0.008
Radius	0.49
Electronegativity	0
Ionization	24.5874
Number of isotopes	5
Electronic configuration	1s2
Oxidation states	0
Electron by energy level	2