Helium was discovered in the year 1895, is present with a symbol of He and it belongs to the group called Nobel Gas. The atomic weight is 4.00260. The density of helium is at 293 K: 0.0001787 g/cm3 .
Helium exists in state of gas with a boiling point of 4.2 K and with a heat of vaporization 0.0845 kJ/mol. Helium has a electron configuration of 1s2 . And both minimum oxidation number and maximum oxidation number is 0.