Comment by saagarjha
7 years ago
> Hydrogen and helium are notoriously hard to contain because their molecules are so small.
You probably didn't mean "helium molecule"–or if it was, that would very odd, as helium as a molecule is very rare…
7 years ago
> Hydrogen and helium are notoriously hard to contain because their molecules are so small.
You probably didn't mean "helium molecule"–or if it was, that would very odd, as helium as a molecule is very rare…
I've heard plenty of good chemists refer to monatomic gases (and sometimes ions) as molecules, or "molecular", colloquially, and particularly when talking generically in terms where they could be replaced by another gas. That helium is monatomic is both well understood and not especially relevant in many contexts.
He2 is rare enough that the few times I've heard it spoken about, people have usually said "helium dimer" to make it clear that's what they mean. Since that's the rare case, it's the logical one to be explicit about.
> I've heard plenty of good chemists refer to monatomic gases (and sometimes ions) as molecules, or "molecular", colloquially, and particularly when talking generically in terms where they could be replaced by another gas.
I have also seen this, but it has normally been almost exclusively confined to when people talk about the "particles" of gas from a kinetic theory point of view.
A single-atom molecule is a very simple molecule. But it is a molecule: "The smallest part of any substance which possesses the characteristic properties and qualities of that substance, and which can exist alone in a free state."
Molecular helium happens to be identical with atomic helium, where an atom is the smallest unit of an element (not a chemical substance).
Water (H20) is a substance whose smallest unit is a molecule of 1 oxygen + 2 hydrogen atoms. Helium is a substance who's smallest unit is 1 helium atom.
Generally molecules are required to consist of at least two atoms bound bound together. For example, here's what Wikipedia defines them as:
> A molecule is an electrically neutral group of two or more atoms held together by chemical bonds.
Literally the next paragraph:
> In the kinetic theory of gases, the term molecule is often used for any gaseous particle regardless of its composition. According to this definition, noble gas atoms are considered molecules as they are monatomic molecules.[9]
1 reply →
Hydrogen molecules (2 atoms) are much larger than the single-atom helium molecules. This is why helium gas is uniquely difficult to seal.
Yep that's why you need to get your kids party balloons on the same day as the party.
The best kind of correct...
Do you think anyone's understanding was negatively impacted by the use of the word 'molecule' here?
No, not really. But I thought it might be an interesting point to share.
Helium is a 'noble element', check the Periodic Table and tell me how Helium gets to be part of a molecule. Unless a lot has changed since I was at school then you aren't going to get a lot of helium 'molecules'. It just doesn't work like that.
What I don't get is how these helium molecules diffuse into the iPhones so easily, an awful lot of helium must have to leak for that. Normally helium - balloon sized quantities - tends to prefer going skyward rather than hide in an iPhone.
But since that seems to not be the case it would be good to turn up at a concert where everyone is playing with their hand rectangles rather than enjoying the moment, then to release some helium to fix that for them...
> Helium is a 'noble element', check the Periodic Table and tell me how Helium gets to be part of a molecule. Unless a lot has changed since I was at school then you aren't going to get a lot of helium 'molecules'. It just doesn't work like that
Yeah, well maybe they don't tell you all the details and special cases in school...
https://en.m.wikipedia.org/wiki/Noble_gas_compound
I checked the link and now I see why you didn't post the relevant quote:
"There is some empirical and theoretical evidence for a few metastable helium compounds which may exist at very low temperatures or extreme pressures. The stable cation HeH+ was reported in 1925."
Maybe you do get these things happening inside a particularly pedantic iphone but regular chemistry suffices here, the general idea of the Periodic Table stands true, noble gasses on the right hand side don't react to instantly form co-valent bonds with the other elements. Sure, anything can happen in the side of a giant thermo-nuclear reactor but, in every day situations classical understanding works great.
I am well aware that helium is a noble gas, and generally does not form molecular compounds. Under the right conditions, though, helium can from molecules bound with the van der Waals force: https://en.wikipedia.org/wiki/Helium_compounds
So under giga-pascal pressures at temperatures approaching absolute zero - are we talking about needing a black hole for that? Are these the 'right conditions' we are talking of?
This is a long way off the article, you are having a laugh!