Considering structures A-D, classify each pair of compounds as isomers, resonance structures, or

Considering structures A-D, classify each pair of compounds...

Considering structures $\textbf{A-D}$, classify each pair of compounds as isomers, resonance structures, or neither: (a) $\textbf{A}$ and $\textbf{B;}$ (b) $\textbf{A}$ and $\textbf{C;}$ (c) $\textbf{A}$ and $\textbf{D;}$ (d) $\textbf{B}$ and $\textbf{D}$.

Key Concepts

Resonance Structures

Resonance structures are different Lewis representations of the same molecule used to illustrate delocalized electrons among atoms. They do not represent distinct compounds but rather contribute to a hybrid structure that more accurately reflects the true electron distribution within a molecule, enhancing the understanding of its stability and reactivity.

Isomerism

Isomerism refers to the phenomenon where compounds share the same molecular formula but differ in the connectivity or spatial arrangement of their atoms. This concept is central to understanding how molecules with identical compositions can exhibit different chemical and physical properties based on how their atoms are linked together or oriented in space.

Transcript

00:01 To classify whether a pair of compounds are isomerase resonance structures or neither, the first step is to determine their molecular formulas.

00:10 So i've done that for you already.

00:12 A is c2h -4 -02, b, c2h -4 -02, c -2h -5 -02, and d, c2h -2.

00:22 I'm just adding up the number of atoms within each of those structures.

00:26 It wants us to compare a and b to start with.

00:30 Well, first we need to know what a number of.

00:31 An isomer is, what a resonance structure is, and then we can determine neither from there.

00:37 So an isomer is two compounds that have the same molecular formula, but they're connected in a different fashion.

00:44 So the atoms are actually connected differently.

00:47 Nothing about the actual number of bonds or number of electrons, but different connectivity of physical atoms.

00:55 Resonant structures have the same molecular formula and the same atom connectivity.

01:01 You're just, pushing electrons, pushing pie bonds, pushing electrons.

01:07 And then neither, of course, probably is just not going to have the same molecular formula.

01:13 So let's compare a and b.

01:15 Well, they have the same molecular formula, so it has to be either an isomer or a resonant structure.

01:22 So the next thing you want to look at is how the atoms are actually connected.

01:26 Well, you have ch3c.

01:28 In this case, it's bonded to two oxygens, one of them's in alcohol.

01:33 Ch3, c, oxygen, oh, h.

01:36 So they have the same connectivity.

01:39 You're just pushing electrons instead.

01:42 So they must be resonant structures, and at the end we'll draw some arrows to prove that.

01:49 Compare a and c.

01:50 Well, a has a molecular formula of c2h4 of 2.

01:54 C has a molecular formula of c2h5 .02.

01:58 Already, that tells us they can't be is.

02:00 Or resonance structures, so the answer is neither.

02:05 Compare a and d.

02:06 Have the same molecular formula, so it could be an isomer or a resonant structure...

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