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Condensed structures

How to go from Lewis dot structures to partially condensed structures to condensed structures.

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  • male robot donald style avatar for user vanaparthisuhas
    how we can decide the central atom in condensed structure?.?.?.?
    (7 votes)
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  • male robot hal style avatar for user Dakshina Sarma
    in the second example (CH3)3COCH3, why don't we use the last CH3 in the first part of the formula? i mean why don't we write it as (CH3)4CO?
    (3 votes)
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    • starky sapling style avatar for user Jm Cresencio
      (CH3)4CO is not possible because the central Carbon now forms 5 bonds which is not possible because Carbon can only form a maximum of 4 bonds. How do i know that? Well Carbon already has 4 valence electrons which means that it only needs 4 more electrons to complete its octet
      (7 votes)
  • aqualine ultimate style avatar for user H.S.J
    The difference between saturated and unsaturated in organic chemistry?
    (2 votes)
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  • blobby green style avatar for user Jeffrey Rose
    It looks like he has one to many CH3 groups.
    My question is how do you draw the Lewis structure for HCO3 and H2CO3?
    Thank you.
    Jeff
    (2 votes)
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    • hopper jumping style avatar for user Shubhangi Mani
      1.Carbon will be in the middle to that 3 oxygen will be attached and to one of the oxygen a hydrogen grp will be attached .between carbon and oxygen their will be a partial double bond present(a single bond present for the one attached to hydrogen)

      2.Carbon will be in the middle to that 3 oxygen will be attached and to 2 of the oxygen a hydrogen grp will be attached . there will be a double bond between one of the oxygen and carbon atom
      (2 votes)
  • piceratops ultimate style avatar for user Kevin George Joe
    at he doesnt draw the lone pairs on the condensed structure. do i always leave out the lone pairs on the condensed structure diagram?
    (1 vote)
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  • starky ultimate style avatar for user DeepShankarPratap
    At (CH)3COCH3, Is the Centered Carbon primary,secondary or tertiary?
    (1 vote)
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    • female robot grace style avatar for user tyersome
      Given that the definitions for primary through quaternary carbons are based on how many other carbon atoms are attached - what do you think the answer is?

      Look at the Lewis structure , there are three bonds to the carbons of -CH₃ groups and one to oxygen. That means the central carbon is a tertiary carbon.

      Note that the condensed structure is actually (CH₃)₃COCH₃.
      (2 votes)
  • blobby green style avatar for user Rachael Lim
    Would it matter if you put the OH first before the O in a condensed formula?
    (1 vote)
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  • piceratops ultimate style avatar for user Asif Sultan
    At you cannot tell how you will rearrange the condensed structure into partially condensed or lewis structure because you can't know where to place the two alkyl groups. Do you place both of them on the same side of the alpha carbon (both on left or both on right) or you will place each of them on either side separately.
    So you can't tell if it's a primary or secondary alcohol. Thus you cannot predict it's reactions, so why do we use these structures? I don't see any real purpose here. If you say "for convenience", well it doesn't allow you to predict properties and reactions, etc. and for that you will have to write the lewis or, if you are looking for convenience, partially condensed structure which shows the bonds, geometry and functional groups. So why do we use these pretty useless structures?
    (1 vote)
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    • mr pants purple style avatar for user Ryan W
      In condensed structures you group all the same things together, so rather than (CH3)C(CH3) you would do C(CH3)2, but I agree with you, condensed formulas for anything remotely complex is basically a waste of time. Just draw the line structures or give the name, it’s way easier.
      (2 votes)
  • aqualine ultimate style avatar for user sreekar273
    As I leaned about condensed structures , the first one should be condensed and the second close condensed structures .. then which one is the correct one among these?
    (1 vote)
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  • starky ultimate style avatar for user MackMonsterT
    Can someone Give me a random Molecular Formula? I wanna see if i can Make it into a Lewis dot structure to see if I actually understand it.
    (1 vote)
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Video transcript

- Let's say we're given the molecular formula C three H eight O, and we're asked to draw a Lewis dot structure. So on the left here is one possible Lewis dot structure that you can draw that has that molecular formula. There are three carbons, one, two, three. There's one oxygen, right here. And if you count up the hydrogens you will get eight. And this Lewis dot structure, let me go ahead and write that, this is a Lewis dot structure here, this one shows all of the bonds. So all the bonds are drawn in. But it takes a lot of time to draw in all the bonds and so we could represent this molecule in different ways. We could condense this Lewis structure a little bit. So this is equal to the structure I'm about to draw. And we'll focus in on the carbon I just circled there in red. So that carbon is this one right here. That carbon is bonded to an OH, so we can say this is an OH right here. Putting lone pairs of electrons on the oxygen. And that carbon is also bonded to this hydrogen, let me draw in that hydrogen. On the right side that carbon in red is bonded to this carbon in magenta. And the carbon in magenta is bonded to three other hydrogens. So we could represent that as a CH three. So I could write CH three here, and the carbon in red is this one and the carbon in magenta is this one. On the left side, the carbon in red is bonded to another carbon in blue and the carbon in blue is bonded to three hydrogens, so there's another CH three on the left side, so let me draw that in, so we have a CH three on the left and the carbon in blue is directly bonded to the carbon in red. So this is called a partially condensed structure so this is a partially condensed, partially condensed structure. We haven't shown all of the bonds here but this structure has the same information as the Lewis structure on the left. It's the same molecule it's just a different way to represent that molecule. We could keep going. We could go for a fully condensed structure. So let's do that. Focus in on the carbon in red. So this one right here. So let me draw in that carbon over here. So that's that carbon. That carbon is bonded to two CH three groups. There's a CH three group on the right, so there's the CH three group on the right. And there's a CH three group on the left. So I could write CH three and then I could write a two here which indicates there are two CH three groups bonded to directly bonded to the carbon in red. What else is bonded to the carbon in red? There's a hydrogen, so I'll put that in. So the carbon is bonded to a hydrogen. The carbon is also bonded to an OH, so I'll write in here an OH. This is the fully condensed version, so this is completely condensed and notice there are no bonds shown. Right, there are no bonds drawn in here, you have to infer you have to infer the bonding from the condensed. All right, let's start with the condensed and go all the way to a Lewis structure, so we'll start with a condensed and then we'll do partially condensed structure, and then we'll go to a full Lewis structure. Just to get some more practice here. So I'll draw in a condensed one, so we have CH three, three and then COCH three. All right let's turn that into a partially condensed structure. So this carbon in red right here we're gonna start with that carbon, so I'll start drawing in that carbon right here. What is bonded to that carbon? Well, we have CH three groups and we have three of them. So there are three CH three groups directly bonded to that carbon. So let me draw them in. So here's one CH three group here is another CH three group, and then finally here's the third CH three group. So this carbon in red over here is this carbon. The carbon in red is also bonded to an oxygen all right, so we need to draw in an oxygen next. So now we have our oxygen. Notice the carbon in red now has an octet of electrons around it. The oxygen is bonded to another CH three group. So the oxygen is bonded to another CH three and let's draw that in so we have our CH three and since we're doing a partially condensed I won't draw in those bonds. We have CH three like that. I could put in my lone pairs of electrons on the oxygen to give the oxygen an octet of electrons. And now we have our partially condensed structure. If we want to expand it even more, and draw the full Lewis structure, again we start with the carbon in red. So here's the carbon in red, and that carbon is bonded to another carbon and this carbon is bonded to three hydrogens, so I draw in those three hydrogens. So this CH three group that I just drew is this one. All right, next, we have a CH three group on the left side, so I need to draw in a CH three on the left, hopefully I have enough room to do that. I'll squeeze it in here, so we have our hydrogens, and that's our second CH three group. So let me circle it in green here. So here's a CH three. And then finally we have let me make this blue down here, we have another CH three group, so I'll draw that one in. So we have another CH three, we'll make room for all these hydrogens here. And that's the one in blue. So we're drawing out all of the bonds now in our full Lewis structure. Next we have an oxygen, so we have an oxygen right in here, with two lone pairs of electrons on the oxygen. The oxygen is bonded to another CH three. So let me let me pick a color here for that one. So we have another CH three on the right, and let's draw it in. There's a carbon with three bonds to hydrogen. So that's our last CH three group, so let me circle it. This one right here is this one. So that's an important skill, being able to go from a condensed to a partially condensed, to a full Lewis dot structure, and also going the opposite direction. Going from Lewis to partially condensed, and finally to condensed. And usually you'll only see these used for small molecules. Right, it's obviously it's obviously easy to work with when you have small molecules. When you have large molecules this doesn't work very well and you'll see almost exclusively bond line structures used to represent larger organic molecules. And we'll look at those in the next video.