Helium gas is unreactive, colourless, and odourless. Helium is available in pressurised tanks. Elemental helium is a colourless odourless monoatomic gas. Helium is the second most abundant element in the universe after hydrogen. Emma's first birthday balloon is filled with helium and so rises in air.
Isolation Here is a brief summary of the isolation of helium.
There is very little helium on earth as nearly all present during and immediately after the earth's formation has long since been lost as it is so light. Just about all the helium remaining on the planet is the result of radioactive decay. While there is some helium in the atmosphere, currently its isolation from that source by liquefaction and separation of air is not normally economic. This is bacause it is easier, and cheaper, to isolate the gas from certain natural gases. It is isolable from these gases by liquefaction and separation of from the natural gas.