[Corvettaholic]

This is what I know about helium, its a noble gas, fairly tiny, and exists as He₂. Correct so far? Got a couple questions about it:

1) Does it have a double bond or a triple bond, and why? I thought its inert and wants to stay really simple.

2) I've heard He₃ exists, whats up with that stuff? And why wouldn't it want to go back to a more simple form of He₂?

3) For those with bio-chemistry knowledge, why does it make your voice high-pitched when you inhale it? (come on, everyone did it as a kid)

[Mitch]

A)It exists as He not He₂. You might be confusing He² with He₂.

1) No bonds

2) See part A and then ask again.

3) Helium will fly pass your vocal cords much faster then O2/N2 thats why your voice gets "higher". If you huff some xenon your voice will get deeper.

[hmx9123]

To add to Mitch's #3: Helium is less dense than air (nitrogen/oxygen mix mostly), which accounts for the sound.  Xenon and SF₆ make your voice lower because they have a greater density than air.

I think Mitch is right, too, you're probably referring to the different isotopes of helium, ⁴₂He and ³₂He.  These numbers are actually written directly above and below one another, but we can't do that here on the forums.  The top number is the mass number and the bottom is the # of protons in the atom in question.  This is standard notation for nuclear chemistry.

[Scratch-]

Then if you stood on your head while talking with helium would your voice be deeper?  

[Mitch]

unless you can change the density of a substance by rotating yourself upsidedown, then yes.