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In blatant theft of Fred's idea, and because I didn't know the Naked Baby Jesus Calender would have a sequel, I present the Molecules Bunny Likes Advent Calender!
(Everyone likes a bit of education with their holidays, right?)
December 1st
If we're looking at molecules I like, then there is really only one place to start.
This, my friends, is caffeine, a molecule of great importance.
Caffeine was discovered in 1819 by Frederick Ferdinand Runge, who named it after its presence in coffee. It is found in tea, coffee, gurana, mate, cocoa, and lots of soft drinks. The caffeine they take out of decaff coffee they put into Relentless, and so the cycle of life goes on.
It is, obviously, a stimulant. It's also a mild diuretic, is toxic to some animals (horses, dogs, parrots...why anyone ever thought a parrot on espresso would be a good idea I cannot guess) and has a surprisingly powerful effect on spiders.
On to the interesting bit: the chemistry!
Caffeine is basically planar - flat. Everything except the hydrogens lies in the same plane. The circle inside the six membered ring (on the left) indicates that it's an aromatic ring. You can also draw this ring out with aternating single (-) and double (=) bonds, and if you do that you see that the bonds can be shuffled around to include the right-hand ring in the pattern.
'Aromaticity' is an important concept. It means that the atoms in a ring are all putting some of their electrons into a 'pi system', a ring of electrons above and below the atoms. This makes the ring very stable and hard to break.
The idea of shuffling bonds around, by moving electrons from double bonds onto single bonds, is also an important concept. Chemists call it 'resonance', but that is a silly name. We will call it 'shuffling bonds around' because that is clearer in meaning. Being able to shuffle the bonds around makes a molecule, or part of a molecule, more stable by strengthening the bonds. The more shuffling you can do, the more stable you get. Aromaticity, that ring pattern above, is an extreme case of shuffling bonds around. Ring systems do it so well that all the bonds are equally double-ish, and that's aromaticity.
December 2nd
This is trinitrotoluene. It's an explosive, as I'm sure you know. Pure TNT is yellow and the chap who invented it, one Joseph Wilbrand, used it as a dye. While it gives a powerful explosion it's quite hard to set off and easy to work with - much safer than, say, nitroglycerine, which will explode if you nudge it too hard.
The picture above bears some explaination. It's a ball-and-stick model. The balls are atoms and the sticks are bonds. Unfortunately this makes the exact kind of bond we're looking at quite hard to see. Drawn out flat, TNT looks like this:
All those N-O bonds can be shuffled around, and so can all the C-C bonds. That's another aromatic ring in the middle, so that part of the molecule is flat. If you look back at the first picture for a moment, you'll see that the bottommost NO2 group is in the same plane as the carbon ring. That tells us that double bonds can also be shuffled around between the ring and that NO2, which - you guessed it - makes it more stable.
We can't do that with the other two NO2's. They don't sit in the right plane. They're tilted to avoid hitting the CH3 group. This sort of problem comes up a lot, and is called 'steric hindrance' or 'steric distortion'. 'Steric' means, roughly speaking, that the effect is caused by the atoms taking up space. Two atoms can't be in the same place at once, so one of them has to move out of the way.
We can only shuffle bonds around when things are in the same plane, so those two NO2s are out in the cold.
NO2 has some very efficient shuffling going on all by itself, though. There's actually no way to tell which of the oxygens is N-O and which is N=O, because the shuffling means they're both about a one-and-a-half bond. Nice and stable. The shuffling is how we get around what looks like a single bond to an oxygen - oxygen hates just having one bond. Notrogen can maintain this arrangement because, while it really likes to have three bonds, it can cope with four by becoming positively charged. We ought to draw it ought with a '+' on the nitrogen and a '-' shared between the oxygens
The explosiveness of TNT comes from all those oxygens, which speed up burning, and from the fact that when you burn this molecule you go from two solid molecules to fifteen gas molecules, which take up much more space. All that hot gas pushes outwards and give you an explosion.
(Everyone likes a bit of education with their holidays, right?)
December 1st
If we're looking at molecules I like, then there is really only one place to start.
This, my friends, is caffeine, a molecule of great importance.
Caffeine was discovered in 1819 by Frederick Ferdinand Runge, who named it after its presence in coffee. It is found in tea, coffee, gurana, mate, cocoa, and lots of soft drinks. The caffeine they take out of decaff coffee they put into Relentless, and so the cycle of life goes on.
It is, obviously, a stimulant. It's also a mild diuretic, is toxic to some animals (horses, dogs, parrots...why anyone ever thought a parrot on espresso would be a good idea I cannot guess) and has a surprisingly powerful effect on spiders.
On to the interesting bit: the chemistry!
Caffeine is basically planar - flat. Everything except the hydrogens lies in the same plane. The circle inside the six membered ring (on the left) indicates that it's an aromatic ring. You can also draw this ring out with aternating single (-) and double (=) bonds, and if you do that you see that the bonds can be shuffled around to include the right-hand ring in the pattern.
'Aromaticity' is an important concept. It means that the atoms in a ring are all putting some of their electrons into a 'pi system', a ring of electrons above and below the atoms. This makes the ring very stable and hard to break.
The idea of shuffling bonds around, by moving electrons from double bonds onto single bonds, is also an important concept. Chemists call it 'resonance', but that is a silly name. We will call it 'shuffling bonds around' because that is clearer in meaning. Being able to shuffle the bonds around makes a molecule, or part of a molecule, more stable by strengthening the bonds. The more shuffling you can do, the more stable you get. Aromaticity, that ring pattern above, is an extreme case of shuffling bonds around. Ring systems do it so well that all the bonds are equally double-ish, and that's aromaticity.
December 2nd
This is trinitrotoluene. It's an explosive, as I'm sure you know. Pure TNT is yellow and the chap who invented it, one Joseph Wilbrand, used it as a dye. While it gives a powerful explosion it's quite hard to set off and easy to work with - much safer than, say, nitroglycerine, which will explode if you nudge it too hard.
The picture above bears some explaination. It's a ball-and-stick model. The balls are atoms and the sticks are bonds. Unfortunately this makes the exact kind of bond we're looking at quite hard to see. Drawn out flat, TNT looks like this:
All those N-O bonds can be shuffled around, and so can all the C-C bonds. That's another aromatic ring in the middle, so that part of the molecule is flat. If you look back at the first picture for a moment, you'll see that the bottommost NO2 group is in the same plane as the carbon ring. That tells us that double bonds can also be shuffled around between the ring and that NO2, which - you guessed it - makes it more stable.
We can't do that with the other two NO2's. They don't sit in the right plane. They're tilted to avoid hitting the CH3 group. This sort of problem comes up a lot, and is called 'steric hindrance' or 'steric distortion'. 'Steric' means, roughly speaking, that the effect is caused by the atoms taking up space. Two atoms can't be in the same place at once, so one of them has to move out of the way.
We can only shuffle bonds around when things are in the same plane, so those two NO2s are out in the cold.
NO2 has some very efficient shuffling going on all by itself, though. There's actually no way to tell which of the oxygens is N-O and which is N=O, because the shuffling means they're both about a one-and-a-half bond. Nice and stable. The shuffling is how we get around what looks like a single bond to an oxygen - oxygen hates just having one bond. Notrogen can maintain this arrangement because, while it really likes to have three bonds, it can cope with four by becoming positively charged. We ought to draw it ought with a '+' on the nitrogen and a '-' shared between the oxygens
The explosiveness of TNT comes from all those oxygens, which speed up burning, and from the fact that when you burn this molecule you go from two solid molecules to fifteen gas molecules, which take up much more space. All that hot gas pushes outwards and give you an explosion.
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