Questions on chemistry

[sciart]

Hi,

 

I came across these questions when I was revising my chemistry studies. If you guys could help me out?

 

1. It says "......polyatomic ions. These ions, which act as discrete units, are positively or negatively charged combinations of two or more atoms."

What does 'discrete units' actually mean in this situation?

 

2. What is the difference between inorganic compounds and organic compounds? Why are they seperated?

 

3. What is absolute zero?

 

Thanks

[insane_alien]

1. discrete units means a multi atomed ion is acting like a exceptionally large monatomic ion. for instance lets takea methyl carbocation(methane missing a hydrogen and an electron.) so we have [CH3]+ this will act like its just a generic monatomic positive ion ie [X]+ where X is any element you want.

 

2.organic and inorganic classification is really a hold over from the early days of chemistry, organic compounds were thought to only be produced inside a living body because they needed a life force or something. then some geezer made urea in a lab. so now any compound that is based on carbon(and includes a selection of hydrogen, nitrogen, oxygen, and less commonly sulphur and the rest of the main group elements) inorganic compunds are everything else.

 

3. the coldest temperature you can get 0K where K stands for kelvin(sometimes called the absolute temperature scale) this is -273.15*C at this temperature all atomic motion stops, there is no kinetic energy.

[5614]

so now any compound that is based on carbon(and includes a selection of hydrogen, nitrogen, oxygen, and less commonly sulphur and the rest of the main group elements)

Is a buckyball, a compound made only from carbon, considered organic? As it does not include any other elements.

 

3. the coldest temperature you can get 0K where K stands for kelvin(sometimes called the absolute temperature scale) this is -273.15*C at this temperature all atomic motion stops, there is no kinetic energy.

Note this temperature can never actually be reached.

[insane_alien]

Well theres always a few exceptions in chemistry. its practically a rule that ever rule has an exception.

[5614]

Yeah... but is this one?

[RyanJ]

Yeah... but is this one?

 

I believe buckyballs are considered to be organic... some people consider them to be composed of hydrogen and carbon but then there are loads of exceptiosn there too...

 

Cheers,

 

Ryan Jones

[insane_alien]

yeah its one of those rules that has a few exceptions. buckyballs are all carbon and organic. well so says the mass spectrometer in my uni. i'll assume its accurate.

[RyanJ]

yeah its one of those rules that has a few exceptions. buckyballs are all carbon and organic. well so says the mass spectrometer in my uni. i'll assume its accurate.

 

My organic chemistry book also covers them so I agree with you

 

Cheers,

 

Ryan Jones

[5614]

Another interesting point I noticed recently when looking at a picture of a buckminsterfullerene was that each carbon has 3 bonds... they should have 4. My chemistry teacher suggested that the electrons could be located in the center of the ball... although I think he was guessing and I don't really know.

[RyanJ]

Another interesting point I noticed recently when looking at a picture of a buckminsterfullerene was that each carbon has 3 bonds... they should have 4. My chemistry teacher suggested that the electrons could be located in the center of the ball... although I think he was guessing and I don't really know.

 

I have heared that too... there was a theory about nanotubes being possible candidates for superconductors, if there are electrons located in the center then that could lead to some interesting properties I guess...

 

Cheers,

 

Ryan Jones

[Bignose]

I am relatively sure that some of the bonds are double and some are single. Look at the wikipedia article: http://en.wikipedia.org/wiki/Buckyball

 

"The 6:6 ring bonds (between two hexagons) can be considered "double bonds" and are shorter than the 6:5 bonds (between a hexagon and a pentagon).

"

 

Carbons can be really tricky, benzene's carbons really aren't 1-sided and 2-sided... the bond energies sort of get all smeared out so that both sides of the beneze carbons look like 1.5's.

 

I suspect that the drawings of C60 and so on are not drawn with the single and double bonds for conveneince. If every carbon only had 3 bonds, it would have quite a charge (-60 right?), and I think would be exceptionally unstable with that large of charge

[Yggdrasil]

All of the carbons in C₆₀ are sp² hybridized and therefore form 3 sigma bonds and have an electron in a p-orbital which gets delocalized into a conjugated pi-orbital which extends throughout the structure. All carbon atoms in C₆₀ are equivalent, each acting as the vertex of two hexagons and a pentagon. Furthermore, all bond lenghts are the same (wikipedia's statement to the contrary is wrong). In fact, buckminsterfullerene is the simplest molecule with icosahedral symmetry, the point group with the highest symmetry. Such a fact can be seen by examining the IR spectrum which has only 4 absorption lines as predicted by symmetry.