I Have Returned
Mar. 3rd, 2009 09:52 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
tanarillThat was not as long a break as I had anticipated. A mini-break. A break-ette.
But I am back again, because I am a comment whore and writing nothing nets me no comments.
We will start with Awesome Dream Which I Had Last Night. I do not remember the whole thing. But the bit I remember starts with my family going and looking for advanced CASA schools. CASA stands for "Center for Advanced Studies and the Arts," and it was a school I attended instead of fourth period way back in high school. As far as I know, there is only one. Anyway. As it turned out, this CASA was advanced because it was a school for 'gifted' children, where 'gifted' means 'has magical talent oozing out of their pores.'
I didn't go, but while visiting I met and made friends with Rags. Rags' sister, CSkerries, was also attendant. And then, for some reason whih I will not ever know considering that everyone knows dealing with demons is a Bad Idea, Rags sealed one of them into a DDR board.
No, I have no idea either.
But that was what happened. CSkerries was, rightfully, horrified when she found out, by virtue of the fact that you can get demons into objects fairly easily but getting them out again without killing anyone is a bitch and a half. CSkerries' annoyingly superior classmate (and I have no idea where this person came from, but he had red hair and freckles and annoyed the living hell out of everyone) was all 'what did you do that for?!' followed by 'How do we fix it?'
And then pretty much the entire rest of the dream is us running around trying to collect various items which are needed for the deposses, or whatever you call it. For some reason, we were in my Shul to do it, which only makes sense in the context of it being a religious building and more likely to not get blown up. CSkerries and her team were cracking some kind of code. Rags and I and Annoying Redhead were gathering parts/supplies/people. I was also running interference because other members of my Shul kept wandering over to ask what was up.
That's it. I woke up. Good dream, but I would like to know what happened in the end.
Okay, now for Science! With visuals, even.
Sigma bonds are fairly simple. We'll use carbon, because it likes to form four bonds and conforms nicely to the models. If you have a single carbon floating in space, it'll have electrons in the 2s and 2p orbitals.
If you bring another atom nearby, though, the orbitals react by hybridizing into these sp3 orbitals. That is, the 2s and the three 2p orbitals combine to form four sp3 orbitals.
In the drawing, the solid circle is meant to be the 2s orbital and the dashed figures the 2p orbitals. When hybridized, the total numbers of electron and orbitals don't change, and like regular orbitals, they occupy the same space at the same time. Only the shape has changed.
If you overlap one sp3 orbital with either an s orbital or another sp3 orbital, it forms a sigma bond. That is, the electrons end up mostly in the region of overlap, caught between the two atoms. These are the most common types of bond.
Pi orbitals only occur during double- or triple-bonding. We'll use carbon again. Suppose you have two carbon atoms, sigma-bonded to each other. Each carbon still has another three possible bonds. But, and here is the important point, any two atoms can only form one sigma bond to each other. That doesn't mean the carbons can't form all sigma bonds; if those other sp3 orbitals formed bonds with hydrogens, for example, all the bonds would be sigma. But if the carbons want to double bond, they must form a pi bond.
To do this, both atoms need a free p-orbital, so the orbital shapes change again. One of the p orbitals dehybridizes (no, that's not a word), leaving 3 sp2 orbitals and one p-orbital. The p-orbitals line up. For the sake of argument, we will say they extend above and below the atom. If it is easier, think that they extend parallel to the z-axis, in an xyz coordinate system. Then they overlap, to make a kind of very wide donut. And that is a pi bond.
The carbons can form a second pi bond in the same way. An sp2 orbital dehybridizes to leave 2 sp orbitals and another free p-orbital. There can't line up in the same direction as the last pi bond, so instead of being above and below the atoms, the extend forward and back, parallel to the y-axis. (Pretend like it is coming out of the screen at you.) Then they overlap, and that forms the second pi bond.
Another pi bond can't form, though, because there are no more axes: the x-axis contains the sigma bond, the z and y axes the pi bonds. The fourth bond must form with something else. It can be another carbon, a hydrogen, or any other covalently bonding atom. The bonds formed that way will be sigma bonds.
Therefore, when counting sigma vs. pi bonds, all single bonds are sigma bonds, and the first bond in a double- or triple-bond is also a sigma bond. The second and third bonds are pi bonds.
I will do alkyls next. As a teachy question, have you covered the naming of alkanes yet? Alkyls and alkanes are closely related, this is why I ask.
But I am back again, because I am a comment whore and writing nothing nets me no comments.
We will start with Awesome Dream Which I Had Last Night. I do not remember the whole thing. But the bit I remember starts with my family going and looking for advanced CASA schools. CASA stands for "Center for Advanced Studies and the Arts," and it was a school I attended instead of fourth period way back in high school. As far as I know, there is only one. Anyway. As it turned out, this CASA was advanced because it was a school for 'gifted' children, where 'gifted' means 'has magical talent oozing out of their pores.'
I didn't go, but while visiting I met and made friends with Rags. Rags' sister, CSkerries, was also attendant. And then, for some reason whih I will not ever know considering that everyone knows dealing with demons is a Bad Idea, Rags sealed one of them into a DDR board.
No, I have no idea either.
But that was what happened. CSkerries was, rightfully, horrified when she found out, by virtue of the fact that you can get demons into objects fairly easily but getting them out again without killing anyone is a bitch and a half. CSkerries' annoyingly superior classmate (and I have no idea where this person came from, but he had red hair and freckles and annoyed the living hell out of everyone) was all 'what did you do that for?!' followed by 'How do we fix it?'
And then pretty much the entire rest of the dream is us running around trying to collect various items which are needed for the deposses, or whatever you call it. For some reason, we were in my Shul to do it, which only makes sense in the context of it being a religious building and more likely to not get blown up. CSkerries and her team were cracking some kind of code. Rags and I and Annoying Redhead were gathering parts/supplies/people. I was also running interference because other members of my Shul kept wandering over to ask what was up.
That's it. I woke up. Good dream, but I would like to know what happened in the end.
Okay, now for Science! With visuals, even.
Sigma bonds are fairly simple. We'll use carbon, because it likes to form four bonds and conforms nicely to the models. If you have a single carbon floating in space, it'll have electrons in the 2s and 2p orbitals.
If you bring another atom nearby, though, the orbitals react by hybridizing into these sp3 orbitals. That is, the 2s and the three 2p orbitals combine to form four sp3 orbitals.
In the drawing, the solid circle is meant to be the 2s orbital and the dashed figures the 2p orbitals. When hybridized, the total numbers of electron and orbitals don't change, and like regular orbitals, they occupy the same space at the same time. Only the shape has changed.
If you overlap one sp3 orbital with either an s orbital or another sp3 orbital, it forms a sigma bond. That is, the electrons end up mostly in the region of overlap, caught between the two atoms. These are the most common types of bond.
Pi orbitals only occur during double- or triple-bonding. We'll use carbon again. Suppose you have two carbon atoms, sigma-bonded to each other. Each carbon still has another three possible bonds. But, and here is the important point, any two atoms can only form one sigma bond to each other. That doesn't mean the carbons can't form all sigma bonds; if those other sp3 orbitals formed bonds with hydrogens, for example, all the bonds would be sigma. But if the carbons want to double bond, they must form a pi bond.
To do this, both atoms need a free p-orbital, so the orbital shapes change again. One of the p orbitals dehybridizes (no, that's not a word), leaving 3 sp2 orbitals and one p-orbital. The p-orbitals line up. For the sake of argument, we will say they extend above and below the atom. If it is easier, think that they extend parallel to the z-axis, in an xyz coordinate system. Then they overlap, to make a kind of very wide donut. And that is a pi bond.
The carbons can form a second pi bond in the same way. An sp2 orbital dehybridizes to leave 2 sp orbitals and another free p-orbital. There can't line up in the same direction as the last pi bond, so instead of being above and below the atoms, the extend forward and back, parallel to the y-axis. (Pretend like it is coming out of the screen at you.) Then they overlap, and that forms the second pi bond.
Another pi bond can't form, though, because there are no more axes: the x-axis contains the sigma bond, the z and y axes the pi bonds. The fourth bond must form with something else. It can be another carbon, a hydrogen, or any other covalently bonding atom. The bonds formed that way will be sigma bonds.
Therefore, when counting sigma vs. pi bonds, all single bonds are sigma bonds, and the first bond in a double- or triple-bond is also a sigma bond. The second and third bonds are pi bonds.
I will do alkyls next. As a teachy question, have you covered the naming of alkanes yet? Alkyls and alkanes are closely related, this is why I ask.
![[identity profile]](https://www.dreamwidth.org/img/silk/identity/openid.png){kind=small}
no subject
Date: 2009-03-04 03:26 am (UTC)no subject
Date: 2009-03-05 12:24 am (UTC)Actually it was supposed to be a Very Strange gift, like maybe a term project. I don't see that makes it any better, but there you are.
no subject
Date: 2009-03-05 12:00 am (UTC)The alkanes are named according to the number of carbon atoms, right? Methane, ethane, propane, butane, and then following the greek numbers... What we didn't cover well were things like isobutane. I mean, the teacher went over it, but I honestly can't understand anything he says unless I've studied it before somewhere else. ._.U
::::
...So, the demon couldn't get out of the DDR, or could it still kill people through it? That would make an awesome trap for unsuspecting enemies. They would know it was dangerous, and they would still want to try it out. XD
no subject
Date: 2009-03-05 12:35 am (UTC)Pi bond are overlapping p-orbitals, yes. I always found that easier to remember.
Yup, that is what I needed to know. Not having to explain that first makes everything much easier!
Nope, it was stuck and inert. Seems like a weird thing to be so worried about, but it was a dream. And my dreams ne ver made much sense XD
no subject
Date: 2009-03-05 06:17 am (UTC)...I kind of want that DDR now. o.o