(c) Do you expect the O—O bond in H 2 O 2 to be longer or shorter than the O—O bond in O 2 ? Explain.

Hello. Everyone in this video we're taking a look at different lewis structures and risk ranking the carbon auction bonding of three different molecules from longest to shortest. So let's go ahead and also recognize before we draw the lower structure, we need to know the number of valence electrons here. We're only dealing with two different atoms carbon and oxygen. So carbon is in group four a. So that gives us four bands electrons And oxygen is a group 68. So there's going to be six valence electrons. Alright, so first molecule that we're dealing with is going to be our C. O. So we have four advanced electrons from that one carbon and then we have six valence electrons from our oxygen. Four plus six is equal to 10. So in this molecule we have 10 fans electrons. So drawing out the lewis structure, we have our cartman and auction adam connected through a triple bond and to fulfill its octet will give one lone pair to each atom. Next we have R. C. 02. So really well known carbon dioxide, so C. 02. Again we have that one carbon atom that's four fans electrons And then we have two oxygen atoms each giving us six bands electrons. They're just doing the math here. Now We have the four plus and two sexes. That's going to equal to 16 valence electrons. Now we have our carbon is our central atom Double bonded to two oxygen's and now the carbon has fulfilled its octet But the oxygen still needs four valence electrons, how can do that? It's just by giving it too long pairs per adam. Alright now, lastly we're moving on to our an eye on here because of the two minus charge. So we have C 032 minus. Let's just temporarily ignore that two minus charge. So our carbon provides us for veils electrons And this time we have three Auction items each giving us six electrons And so doing the math. Heard we are given a sum of fans electrons. Now we can deal with the two minus charge having to minus charge. Just means that we have two extra electrons adding to here. 32 plus two is 34 electrons join the lower structure for that will have carbon again being the central atom connected to three oxygen atoms. So oxygen usually likes to have two bonds. However, that would break octave rules if we have double bonds for each oxygen atom so we'll only give to one of them. And of course we need to fulfill its octet rule still. So we'll just go ahead and fill in with long pairs in this ocean Adam will have a negative one charge as well as this one right here. And if you add the formal charges of negative one and negative one, you'll get negative two just like the iron suggests. And so let's see here to keep in mind when ranking the bond lengths, it's that our single bond is going to be the longest but the weakest then we have our double bond which is just in the middle and then we have our triple bond which is going to be the shortest and the strongest. So think of it as a rubber band, the longer you stretch it, it's going to be longer. Yes but it's definitely going to get a lot weaker. Alright so we can see your hair that we have a clear triple bond and a clear double bond. But what about this one right here? Well we can go ahead and actually draw different resonance structures for this. You can see here we have this pipe on this can go ahead and break and create a long parent. And one of these lone pairs can go ahead and form a double bond so that we can have several resident structures. And because of that we know that resonance structures are kind of like a hybrid of all. To create an accurate representation of the molecule. In that case is that of a double bond. Or a single bond will kind of average it out. And then we have average that's going to actually be 1.5. So we have a triple bond here, we have a double bond and have that 1.5. So because 1.5 is close enough to single, they will name this being the longest but the weakest. And then we have this triple bond here being the shortest and the strongest. So if we follow this little guide map here, then our answer should be again from longest to shortest. We will have a c. two minus, Then CO two unless they are C. O. And this is going to be our final answer for this problem. Thank you all so much for watching.

Ch.8 - Basic Concepts of Chemical Bonding

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Brown 15th Edition

Ch.8 - Basic Concepts of Chemical Bonding

Problem 38c

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Chapter 8, Problem 38c

(c) Do you expect the O—O bond in H₂O₂ to be longer or shorter than the O—O bond in O₂? Explain.

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Identify the molecular structure of both H2O2 (hydrogen peroxide) and O2 (oxygen gas). Hydrogen peroxide has a bent structure due to the presence of lone pairs on oxygen atoms, while oxygen gas is a diatomic molecule with a double bond between the oxygen atoms.

Consider the types of bonds present in each molecule. In H2O2, the oxygen atoms are connected by a single bond, whereas in O2, the oxygen atoms are connected by a double bond.

Recall that double bonds are generally shorter and stronger than single bonds due to the increased electron density between the atoms.

Apply the concept that the length of the bond is inversely related to the bond order (number of chemical bonds between a pair of atoms). A higher bond order typically results in a shorter bond.

Conclude that based on the bond order and the type of bonding, the O—O bond in O2 (double bond) is expected to be shorter than the O—O bond in H2O2 (single bond).

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Bond Length

Bond length refers to the distance between the nuclei of two bonded atoms. It is influenced by factors such as atomic size, bond order, and the presence of lone pairs. Generally, shorter bonds indicate stronger interactions between atoms, while longer bonds suggest weaker interactions.

Bond Order

Bond order is a measure of the number of chemical bonds between a pair of atoms. In simple terms, a higher bond order (e.g., double or triple bonds) typically results in shorter bond lengths due to increased electron sharing. In contrast, a single bond has a lower bond order and is usually longer.

Lone Pairs and Steric Effects

Lone pairs are pairs of valence electrons that are not involved in bonding. In molecules like H2O2, the presence of lone pairs on oxygen atoms can create repulsive forces that affect bond lengths. This steric effect can lead to longer bond lengths compared to molecules with fewer or no lone pairs, such as O2.