The atom - explain me THIS

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Elvistears
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The atom - explain me THIS

Post by Elvistears » Fri Jan 11, 2008 11:48 am

So, I tried to get me some education and watch the programme on BBC 4 the other night about the atom. It was quite interesting, until he started talking about iron being the most stable of all the elements. Apparently the "lighter" elements such as helium and hydrogen are least stable.

This doesn't match up with what I was told at school at ALL. They told us helium, argon, xenon and friends were noble gases and wouldn't react with OWT, because they were just FINE as they were.
Equally, I'm sure iron (nickel and either copper or cobalt were also listed as extremely stable) was quite a bit more reactive than certain other metals - silver and gold, for example.

And doesn't iron rust? Which would indicate reactivity and not stability?

Is it just a different usage for the term "stable"? And if so, what does it mean in this context?

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Post by humblebee » Fri Jan 11, 2008 12:00 pm

All the stuff about atoms and molecules that they taught us at school is bollocks, isn't it? I wouldn't mind so much if they'd thought it was true at the time and then they discovered all the other stuff later. But when you watch these programmes, it's like they've known about subatomic particles and the massive space of nothing inside an atom for fucking decades, and they just taught us the old wrong stuff at school because they couldn't be arsed to change the syllabus. And then they wonder why we don't go on and become scientists when we grow up. Stupid school.

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Post by Elvistears » Fri Jan 11, 2008 12:03 pm

Well, I think they told us about the massive space of nothingness, because I remember being vaguely impressed by it at the time. Is "sub-atomic particle" a posh way of describing a proton, electron or neutron, or is it something posher still?

I should have done chemistry - their mistake was telling me I HAD to, which of course made me want to do something completely different.

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Post by La-Di-Da » Fri Jan 11, 2008 12:06 pm

humblebee wrote:All the stuff about atoms and molecules that they taught us at school is bollocks, isn't it?
When I went from GCSE physics to 'A' level the first thing our tutor told us was "Forget everything you've learnt up until now. It's mostly bollocks."

I should have walked out there and then.

Edit: Sorry. That wasn't at all helpfull.

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Post by Jeezy Creezy » Fri Jan 11, 2008 12:17 pm

I did all the more advanced particle thingimy learning at uni and got bloody As for it as well but I'll be damned if I can 'member any of it in my old age. Could the programme have been talking about the stability of the elements as oxides? Iron oxides are very stable however oxides and other compounds of the noble gases can be very reactive.
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Post by Elvistears » Fri Jan 11, 2008 12:37 pm

It was something to do with the molecular structure of the element being very stable, so I'm not sure they were talking about compounds (although they could have been, and I've just got it all arse about tit). This is, apparently, why the heavier metals will break down to be more like an iron molecule. I think.

It would make sense for a noble gas compound to be unstable. I don't know why a helium molecule would be unstable though?

I suspect

1. they were LYING
2. I got confused (but I don't think so - I can speak basic chemistry, just nothing beyond that)
3. there's something I don't know that explains all this.

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Re: The atom - explain me THIS

Post by soft revolution » Fri Jan 11, 2008 12:48 pm

Hobart Paving wrote:So, I tried to get me some education and watch the programme on BBC 4 the other night about the atom. It was quite interesting, until he started talking about iron being the most stable of all the elements. Apparently the "lighter" elements such as helium and hydrogen are least stable.

This doesn't match up with what I was told at school at ALL. They told us helium, argon, xenon and friends were noble gases and wouldn't react with OWT, because they were just FINE as they were.
Equally, I'm sure iron (nickel and either copper or cobalt were also listed as extremely stable) was quite a bit more reactive than certain other metals - silver and gold, for example.

And doesn't iron rust? Which would indicate reactivity and not stability?
There's a difference between reactivity and stability. How much an element decays radioactively is a measure of it's stability.
And by me, I mean, Flexo.

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Post by Elvistears » Fri Jan 11, 2008 12:51 pm

I thought there might be - this is where Proper Chemistry probably departs from GCSE Chemistry. We were taught stability as the opposite of reactivity.

So - what makes a particular element decay radioactively... or is that a difficult question?

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Post by soft revolution » Fri Jan 11, 2008 1:06 pm

Hobart Paving wrote:I thought there might be - this is where Proper Chemistry probably departs from GCSE Chemistry. We were taught stability as the opposite of reactivity.
Really? I though they were taught as seperate concepts. I might be wrong because I'm only half remembering stuff here. A stable element such as iron can still react with things to form a compound - and the iron atom is still there, what does change is that it creates bonds with other elements.

Decay is how you do carbon dating, it's to do with how much of the carbon 14 has decayed into the more common and stabler carbon 12.
Hobart Paving wrote:So - what makes a particular element decay radioactively... or is that a difficult question?
I'm not sure I can answer this. I think it's a fairly random process where an atom just finds a more stable way of arranging its electrons, protons and neutrons, so it ejects a couple and flops into a more stable state.

Um, like I say I'm half remembering this so if someone with an actual qualification in science wants to come and tell me off for talking about floppy atoms then please do.
And by me, I mean, Flexo.

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Post by Jeezy Creezy » Fri Jan 11, 2008 1:46 pm

Radioactive atoms are ones that have a larger mass than what they should do - there's more of the inner bits that make up an "normal" atom and as they escape they release energy in i.e. radiation and the atom gradually becomes more stable. This process can take thousands and thousands of years there's just so many bits in there. Humans make radoiactive elements by squishing other elements together.
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Post by Elvistears » Fri Jan 11, 2008 2:11 pm

soft revolution wrote:
Hobart Paving wrote:I thought there might be - this is where Proper Chemistry probably departs from GCSE Chemistry. We were taught stability as the opposite of reactivity.
Really? I though they were taught as seperate concepts. I might be wrong because I'm only half remembering stuff here. A stable element such as iron can still react with things to form a compound - and the iron atom is still there, what does change is that it creates bonds with other elements.

Decay is how you do carbon dating, it's to do with how much of the carbon 14 has decayed into the more common and stabler carbon 12.
Perhaps its just a terminology thing. I feel quite sure that what we were told was stability is not the same thing that you're referring to. Which is why I didn't understand that programme and you probably would have done.

Carbon 14...Carbon 12... this is one of those places where I nod and suggest another drink..

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Post by Elvistears » Fri Jan 11, 2008 2:12 pm

[quote="Hobart Paving"]

Perhaps its just a terminology thing. I feel quite sure that what we were told was stability is not the same thing that you're referring to. Which is why I didn't understand that programme and you probably would have done.

[quote]

That's to imply that you know your stuff and what I was taught was...offbeat rather than to imply you're wrong, btw...

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Post by soft revolution » Fri Jan 11, 2008 2:13 pm

Image

Ka-boom (I'm 100% sure that it doesn't make a kaboom noise. Wish it did though)
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Post by Concrete » Fri Jan 25, 2008 7:33 pm

humblebee wrote:All the stuff about atoms and molecules that they taught us at school is bollocks, isn't it? I wouldn't mind so much if they'd thought it was true at the time and then they discovered all the other stuff later. But when you watch these programmes, it's like they've known about subatomic particles and the massive space of nothing inside an atom for fucking decades, and they just taught us the old wrong stuff at school because they couldn't be arsed to change the syllabus. And then they wonder why we don't go on and become scientists when we grow up. Stupid school.
That's just your school, perhaps. The physics I was taught at school wasn't that different from what I was taught at university, apart from the maths got more complicated at university, and we covered stuff like quantum physics. Certainly everything about orbitals and stuff like the relative sizes of an atom and a proton (and therefore the existence of all that space) were consistent with anything I've seen in degree textbooks. Did you do combined science GCSE? I think it helps a little to have done the separate physics GCSE.

"Stability" means different things in different contexts; if you see the word "stabilisers" in a set of ingredients on a food product, it's talking about stability in the sense of molecules not reacting. But if someone talks about something being a "stable element" it's to do with radioactive decay.

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Post by frogblast » Fri Jan 25, 2008 8:14 pm

humblebee wrote:All the stuff about atoms and molecules that they taught us at school is bollocks, isn't it? I wouldn't mind so much if they'd thought it was true at the time and then they discovered all the other stuff later. But when you watch these programmes, it's like they've known about subatomic particles and the massive space of nothing inside an atom for fucking decades, and they just taught us the old wrong stuff at school because they couldn't be arsed to change the syllabus. And then they wonder why we don't go on and become scientists when we grow up. Stupid school.
well the "massive space of nothing inside an atom" has been known about since Rutherford's famous gold foil experiment in 1909, so i don't think that's a case of not updating the syllabus. (it was certainly something i was taught repeatedly, but that was probably at A level, at GCSE age i had the unpleasant habit of reading science books, so i couldn't say if they had taught us that by then or not. i was certainly aware of it.)

in physics it's usually a question of scale: relativity doesn't matter unless you are going incredibly fast, quantum mechanics only makes a difference at a very small scale, so newtonian physics is not wrong as such, it's just a simplified picture.
My experience was similar to Concrete's - physics at university didn't disagree with what i was taught at school, it's just a lot (lot) more mathematical (vector calculus anyone?) and about things at more extreme scales.

anyway, as already mentioned, this is an issue of terminology: stable in a chemical sense or stable in a radioactive sense e.g. the energy released by fussing nuclei together - i think everything up to iron releases energy, above that it takes energy to fuse them together - hence splitting them releases energy. heavier nuclei also have more neutrons per proton to help counteract the problem of having all that positive charge in one place{warning: it's been a while since i did this stuff, and i'm very adept at forgetting such things}

here's a pretty picture of some science:
Image
(i can't remember what it is, but i have it at 2717x1977 resolution if anyone wants it)
Sun like honey on the floor,
Warm as the steps by our back door.

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Post by soft revolution » Fri Jan 25, 2008 9:24 pm

frogblast wrote: (vector calculus anyone?) and about things at more extreme scales.
I've still never been told a real world application for Laplace!
frogblast wrote:here's a pretty picture of some science:
Image
(i can't remember what it is, but i have it at 2717x1977 resolution if anyone wants it)
Those look like the noodly apendages of the Flying Spaghetti Monster to me.
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Post by Concrete » Sat Jan 26, 2008 2:06 pm

frogblast wrote:in physics it's usually a question of scale: relativity doesn't matter unless you are going incredibly fast, quantum mechanics only makes a difference at a very small scale, so newtonian physics is not wrong as such, it's just a simplified picture.
This is one that winds me up when people talk about it on internet forums - how many times have smartarses piped up and said "well, science isn't always right - look at Newton's laws for instance, great bit of science that was, ha ha"? Newton's laws are technically approximations, but anything that Newton was physically able to investigate would have met all the criteria for the approximation to hold. They're still used by engineers, because for objects big enough to hold they do actually work.

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Post by soft revolution » Sat Jan 26, 2008 2:41 pm

Exactly, scientific theory *evolves* over time when new evidence/experimentation methods become available. Doesn't mean what was said before was completely wrong, it was just the best model available at the time.

Its such a brilliant system.
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Post by gofelt » Tue Jan 29, 2008 8:20 pm

Isn't quantum mechanics/theory weird and wonderful? Even now I don't quite understand the probabilistic nature of quantum mechanics. I guess the theory is hard to grasp because the classical concept of the particle was abandoned and probabilites were introduced to interpret atomic world. That's mind boggling. And then all the philosophical consequences of the theory, is our world deterministic or probabilistic?!

I don't know how Schrödinger or Heisenberg came up with the wave function or the Uncertainty Principle. One things is for certain: they were true geniuses..
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Post by Concrete » Tue Jan 29, 2008 9:15 pm

gofelt wrote:Isn't quantum mechanics/theory weird and wonderful? Even now I don't quite understand the probabilistic nature of quantum mechanics. I guess the theory is hard to grasp because the classical concept of the particle was abandoned and probabilites were introduced to interpret atomic world. That's mind boggling. And then all the philosophical consequences of the theory, is our world deterministic or probabilistic?!

I don't know how Schrödinger or Heisenberg came up with the wave function or the Uncertainty Principle. One things is for certain: they were true geniuses..
I hated quantum physics when I was at university, because I wasn't very good at the exams in it (I even had to resit one), but it's actually an interesting concept. We got as far as some practical applications of it by my final year (the central area of my degree was biophysics and medical physics), and of course it's very helpful to know a bit about it when you're trying to understand electron energy levels and stuff. I don't really have to know about stuff like that now though. Shame, as my mother's trying to offload a bookcase full of my father's old textbooks, loads of which are about quantum mechanics and molecular physics. Maybe I'll just choose the ones which look best on a shelf...

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