Periodic table gets a new element | Hacker News Reader

Periodic table gets a new element

news.bbc.co.uk

40 pointshabs16 comments

It seems like an element should have to be stable to be considered an element. This only lasted a few microseconds. Couldn't you put almost any combination of particles together for an arbitrarily short amount of time? What's special about an element?

I can't find it now no matter what, but there is a video in here somewhere where professor talks exactly about that http://www.youtube.com/user/periodicvideos

I rememebr he says something about higher you go in the periodic table you add more electron to the shell and there is only a finite amount of space in there, and at the time, highest element had all of the slots filled in and then something weird about electron orbit.. ugh and I have watched it just the other day.. but there it is, and all of the videos are very interesting (at least to me)

edit: here it is http://www.youtube.com/watch?v=Stxor9L00BU&feature=chann... - a video about element 118 and professor gets asked how can they know there are only 118 elements in about a minute in video

and here is an edited video of all 118 elements they have explained http://www.youtube.com/watch?v=LFsdbLFHgY8&feature=relat...

If you only counted stable substances as "elements", an awful lot of things would have to get a different name. Uranium wouldn't be an element at all, because even U-238 (the most common isotope, more than 99% of the stuff found in nature, http://en.wikipedia.org/wiki/Isotopes_of_uranium) will be reduced by half in a few billion years.

You could set some time limit of half life, below which is considered "completely unstable" and doesn't count, but what purpose would such an arbitrary division serve?

Yes, you can slam particles together in any combination, but the special thing about elements is that, for at least a few microseconds, it didn't need any external force or containment to hold together. A few microseconds is a long time at the subatomic scale.

They are not just particles near each other, but they actually combined into a single particle - an atom.

In the macro world if you put things together, then separate them you get the same pieces back. In the micro world it's not like that - the protons and neutrons combine into a single mixed jumble.

So that's what's special about it, despite it being unstable: at least for a time it was a single particle.

Instability is all about energy, if you release energy by splitting off a particle, it will do so. Guaranteed. If you need energy to do so, it won't. The time it takes to decay is directly proportional to the amount of energy released.

(Another thing that can cause stability is conservation of quantum number like charge and momentum. If it's illegal for a piece to split off, then even if there is a lot of energy, it won't.)

But instability does not imply the atom is somehow less of an atom than another one. It's just an atom at a very high energy level.

Wikipedia states that Ununbium (element 112) was first created in 1996, but that team's research was disregarded. Apparently, we've synthesized elements up to 118, except 117.

It wasn't so much disregarded as retroactively discounted on grounds of fraud. In retrospect, we aren't sure whether any of those elements have ever been synthesized (though I seem to recall reading about 115 in the past year).

"Professor Hofmann began his quest to add to the periodic table in 1976."

This really seems like a poor scientific imperative.

The world would look very different now if Lise Meitner had thought the same thing in 1917.

It's more likely poor journalism.

I am left to wonder though: what is the possible use of this?

I realize it's basic research (and as such am all for it), but it would be interesting to know whether any practical uses are even planned or theorised.

If we could reach the http://en.wikipedia.org/wiki/Island_of_stability we might get some very interesting materials.

Thanks for the Island of Stability link, I had never heard that term before.

But given that the atoms of these elements need to be manufactured with a high energy cost, using them to manufacture pure materials would be prohibitively expensive. As in, physically prohibitive : we would need Kardashev level 1 energy to manufacture macroscopic amounts. I could see an use as dopants though : this would require minuscule amounts of these elements, but it would still be amazingly expensive.

You got downmodded (I think) because it's way way too early to worry about how much energy they take to make. Lets first make them - for all me know by the time we manage it, fusion reactors will be cheap.

But I bumped you back up since I don't think your comment deserves a zero.

Shouldn't 118 have been the pinnacle of the island of stability? It's a noble element...

The electron cloud is noble (i.e. all filled shells/layers).

But the nucleus has it's own shells, and those are the ones that need to be filled for it to be stable.

However not as much is known about the nucleus shells, how many in each level, etc. Read here: http://en.wikipedia.org/wiki/Nuclear_shell_model

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