Three resonance structures can be drawn for CO2. Which resonance structure is best from a formal

Three resonance structures can be drawn for CO2. Which...

Key Concepts

Octet Rule

The octet rule states that atoms tend to be more stable when they are surrounded by eight electrons. Resonance structures that allow atoms, especially second-period elements, to complete their octets are usually preferred for accurately representing the molecule's bonding.

Electronegativity

Electronegativity reflects an atom's ability to attract electrons. In determining the best resonance structure, any negative formal charges should be located on more electronegative atoms, while any positive charges should reside on less electronegative atoms to ensure maximum stability.

Formal Charge

Formal charge is a calculated value that helps determine the electron distribution across a molecule. A resonance structure with minimal formal charges, ideally with zero formal charges when possible, is generally more stable and thus considered the best.

Resonance Structures

Resonance involves drawing multiple Lewis structures to represent the same molecule, where the overall electron density is a hybrid of the various forms. The best resonance structure is usually the one that contributes most to the overall hybrid, typically the structure where electrons are most suitably arranged.

Transcript

00:01 So in this video, we're going to talk about question 104 from chapter 8, which says three resonant structures can be drawn for co2.

00:08 Which resonance structure is best from a formal charge standpoint? so let's go ahead and draw the lewis structure for co2 and then draw some resonant structures.

00:17 So carbon is going to bring four valence electrons, and each of our oxygen atoms bring six valence electrons, so we have a total of 16 electrons to work with.

00:26 And then our less electronegative atom, our carbon atom is going to be our central atom.

00:31 Remember, when you have a choice about what to make your central atom, about which atom to make your central atom, you're going to pick the atom that's less electronegative to be your central atom.

00:42 So we have our carbon bonded to our oxygen, bonded to our oxygen.

00:47 And let's start out just with single bonds and fill in our octet and see what happens.

00:51 That actually uses up all 16 of our electrons.

00:55 So what are our formal charges look like? well, the formal charge in our oxygen atom is 6 minus 6 minus 1.

01:00 That's a formal charge of minus 1.

01:02 And our carbon atom, it's 4 minus 2.

01:05 So it's plus 2.

01:06 So i have minus 1 plus 2 in minus 1.

01:09 So we can do better than that from a formal charge standpoint.

01:13 So what if instead of single bonds to my carbon atom, i made double bonds to my carbon atom.

01:19 And then i just go ahead and fill in my octet on my oxygen atoms in the exact same way...

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