what are the characteristics of it?
In the perspective of quantum mechanics, helium is the second simplest atom to model, following the hydrogen atom.
Helium
In the perspective of quantum mechanics, helium is the second simplest atom to model, following the hydrogen atom. 
where does the world's helium come from Most helium on Earth is a result of radioactive decay and is found in large amounts in minerals of uranium and thorium, including uraninite. how is it extracted? UNANSWERABLE does it have any uses? Yes, commercial, recreational, scientific as well as medical use. what are its commercial use? One of its commercial use is that its mixtures such as trimix, heliox and heliair are used for deep diving to reduce the effects of narcosis, which worsen with increasing depth.
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Helium [SEP] Helium in quantum mechanics
In the perspective of quantum mechanics, helium is the second simplest atom to model, following the hydrogen atom. Helium is composed of two electrons in atomic orbitals surrounding a nucleus containing two protons and (usually) two neutrons. As in Newtonian mechanics, no system that consists of more than two particles can be solved with an exact analytical mathematical approach (see 3-body problem) and helium is no exception. Thus, numerical mathematical methods are required, even to solve the system of one nucleus and two electrons. Such computational chemistry methods have been used to create a quantum mechanical picture of helium electron binding which is accurate to within < 2% of the correct value, in a few computational steps.