Spatial Orientation of Bonds - Online Tutor, Practice Problems & Exam Prep

Spatial Orientation of Bonds Concept 1

This video, we're going to take a look at spatial orientational bonds. Now we're going to say that the skeletal formula also shows how atoms in the molecule are arranged in space in addition to how atoms are bonded. Here we're going to say that atoms or groups on a solid wedge come out of the page, meaning they're above the plane towards the observer. So imagine you're looking at this molecule that O is pointing straight up at you towards your face. So here, this is our solid wedge, meaning that O is pointing straight out of the paper towards you.

We're going to say next that atoms on dashed wedges go inside the page, they lie below the plane, and we're going to say they are away from the observer. So here's our dashed wedged line, that means it goes into the page. So if you want to think about this in terms of 3D, imagine my hand here is a piece of paper, we'd say that the O is a solid wedge, so it's pointing up towards my face, towards my chin. And then we'd say that this group here, which is a CH₃ group, is dashed, so it's below. It's on the bottom, away from my chin. So that's what we mean in terms of orientation and space. We can actually say what direction the group is pointing now based on if it's a solid wedge or a dashed wedge. So hopefully that makes more sense. As we go deeper into skeletal formulas, we'll see these types of bonds pop up here and there.

Spatial Orientation of Bonds Example 1

Here in this example question, it says, identify which groups in the given structure are above or below the plane of drawing. So remember, if you have a solid wedged bond, that means you're above the plane, and if you have a dashed wedged bond, you're below the plane. If we take a look here, at the end of this bond here is a carbon that we don't see. Carbon must make 4 bonds, so it has 3 hydrogens that are invisible. From this image, we'd say what's above the plane would be our CH₃ group here, this OH group, and then what's below would be this NH₂ group, because it's the one with the dashed wedge bond. And those are the only bonds that we see that have either a solid wedge or a dashed wedge. So those are the only options that we can set. Alright. So these would be the answer to this following example question.

Transform the following skeletal formula so that groups 1 and 2 come out of the page and group 3 goes inside the page.

• A.
• B.
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• D.