Helium

Heium, which has the symbol He and atomic number 2, is the first noble gas in the periodic table.

Helium boils at -188.14°C and freezes at -248.67°C (under a pressure of one atmosphere) and therefore only occurs naturally as a gas except under extreme conditions (for example in the core of some giant planets where the very high pressures can force it to a solid state).

Helium is colourless, odourless, tasteless and non toxic, as well as practically inert.

Almost all the helium in the universe comes from the fusion of nuclear hydrogen in the stars, whereas on Earth it is the product of the disintegration of heavier elements such as uranium and thorium. Part of it can be found in natural gas at concentrations of up to 7%.