I have a PhD in chemistry and I've never heard the term before. It sounds like pseudoscientific malarky designed to convince you to buy some worthless product.
A quick Google search turned up the phrase in a patent for a "graviton" (the quotes are in the original as well) microscope "for use in cancer research" (those quotes are mine). So, yep. Snake oil.
No. Each atom (except for Hydrogen) is made up of neutrons, protons, and electrons. Each of these components can be further subdivided into quarks, etc.
They are helium atoms and have all the properties of helium. Helium is mono-atomic [as are all of the noble gases] Non-noble gases [those gases that react with other elements/compounds] are diatomic...