bond length

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Tiffanny_Carranza_2D
Posts: 64
Joined: Fri Oct 02, 2020 12:15 am

bond length

Postby Tiffanny_Carranza_2D » Sat Nov 14, 2020 5:49 pm

are we supposed to know how to calculate bond length?

if so what equation or how do we do that?
thank you

Audrey Han 3L
Posts: 95
Joined: Wed Sep 30, 2020 9:38 pm

Re: bond length

Postby Audrey Han 3L » Sat Nov 14, 2020 5:51 pm

I don't believe so! I think we just need to know the lengths of bonds relative to others, so a double bond is shorter than a single bond, a triple bond is shorter than a double bond, etc.

Edward Tang 1k
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Re: bond length

Postby Edward Tang 1k » Sat Nov 14, 2020 6:11 pm

Agree with what is said above^. Maybe sometimes in resonance structures we will be asked to find the actual bond length when there are say two double bonds and one single bond that can be in any place of the three bonds, in that case we just find the average of all the bond lengths. I'm not sure why it would simply be the average but even if not it would be some value close to the average.

MichaelMendozaD1F
Posts: 55
Joined: Wed Sep 30, 2020 9:55 pm

Re: bond length

Postby MichaelMendozaD1F » Sun Nov 15, 2020 4:46 pm

so how are we able to see which bonds are longer or smaller? like in Q11 of the sapling week 5 and 6 HW?

Jessica Manriquez 1H
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Joined: Wed Sep 30, 2020 9:47 pm

Re: bond length

Postby Jessica Manriquez 1H » Sun Nov 15, 2020 4:49 pm

Like most people have said, i don't think we necessarily have to know how to calculate the bond length, but we should know which bonds are longer and which bonds are shorter; so for example double bonds are shorter than single bonds, but triple bonds are shorter than double bonds, single bonds are always the longest. Hope this helped :)

Keon Amirazodi 3H
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Re: bond length

Postby Keon Amirazodi 3H » Sun Nov 15, 2020 4:52 pm

No, we are not. If we need to know bond lengths for to answer a question, we should be given them.

Jaden Ji 2K
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Re: bond length

Postby Jaden Ji 2K » Sun Nov 15, 2020 4:54 pm

I think the bond lengths would be given if we needed to calculate, but like what other people have been saying, to calculate the resonance structure bonds you just need to calculate the average of all the bonds (triple, double, single). The more single bonds, the longer the resonance bonds would be, and the more triple or double bonds, the shorter.

DPatel_2L
Posts: 70
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Re: bond length

Postby DPatel_2L » Sun Nov 15, 2020 5:13 pm

I don't believe we need to.

Justin Zhang_1A
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Re: bond length

Postby Justin Zhang_1A » Sun Nov 15, 2020 5:14 pm

No, bond lengths will be given in problems if we need the exact length. You should still know the relationship between bond length and strength with single, double, and triple bonds though.

Shivani Kapur 2J
Posts: 95
Joined: Wed Sep 30, 2020 9:59 pm

Re: bond length

Postby Shivani Kapur 2J » Sun Nov 15, 2020 5:15 pm

We don't need to know how to calculate them but we do need to know which bond lengths are stronger and shorter compared to which bond lengths are longer and weaker.

Savannah Torella 1L
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Joined: Wed Sep 30, 2020 9:40 pm

Re: bond length

Postby Savannah Torella 1L » Sun Nov 15, 2020 5:30 pm

We do not need to know how to calculate for bond lengths. In lectures, Dr. Lavelle told us that the values given to us were ones that he looked up, meaning that we wouldn't be expected to find them ourselves. All you need to know is that the bonds from longest to shortest are single, double, triple and how the length compares to the strength of the bond.

Taha 2D
Posts: 80
Joined: Wed Sep 30, 2020 9:50 pm

Re: bond length

Postby Taha 2D » Sun Nov 15, 2020 5:36 pm

We dont need to specific bond lengths but we should know that in resonance hybrid structures all bond lengths are equal(average of the different lengths) and the higher the electron density of the bond, the shorter the bond length

Joanne Yuh 3I
Posts: 103
Joined: Wed Sep 30, 2020 9:42 pm

Re: bond length

Postby Joanne Yuh 3I » Sun Nov 15, 2020 5:38 pm

Yeah, I don't think we need to know the exact bond length because Professor Lavelle said in his lectures that the examples of bond length are from research and that we don't need to memorize them. Also, we just need to know the general trends of bond length through atomic radius trend and other concepts.

Kyla Roche 2K
Posts: 93
Joined: Wed Sep 30, 2020 9:59 pm

Re: bond length

Postby Kyla Roche 2K » Sun Nov 15, 2020 5:39 pm

We don't need to know the exact numbers for bond length but know that single bonds are the longest, then double bonds, then triple bonds are the shortest. The length tells us the strength; the longer the bond, the weaker it is.

Chance Herbert 3A
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Joined: Wed Sep 30, 2020 9:55 pm

Re: bond length

Postby Chance Herbert 3A » Sun Nov 15, 2020 5:47 pm

From everything I have seen so far, the bond length is usually given. I think it would be more beneficial to know what factors contribute to bond length. For example, size of an atom may increase the bond length. Also know that the greater the bond length, the weaker the bond will be.

Jaden Joodi 3J
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Joined: Wed Sep 30, 2020 9:31 pm

Re: bond length

Postby Jaden Joodi 3J » Sun Nov 15, 2020 6:07 pm

I do not believe that we are expected to calculate bond length. BUT, it is important to know trends for bond length. Know that bond length is inversely proportional to bond strength. Also make sure to remember that the larger an atom is, the larger the bond length will be.

Sondia Luong 1C
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Re: bond length

Postby Sondia Luong 1C » Sun Nov 15, 2020 6:09 pm

The bond length will most likely be given in the problem. We could use the bond length to determine which lewis structure best fits the molecule or to determine how tightly held the shared electrons are between atoms.

Carolina Gomez 2G
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Re: bond length

Postby Carolina Gomez 2G » Sun Nov 15, 2020 6:15 pm

I believe we don't need to solve for the exact bond length, but it is possible to estimate what the bond length will be without having to solve for it based on information given. If a molecule has 4 bonds and three are single bonds, then the bond length will be closer to the value given for the expected bond length for single bonds and it will be within the range given for the expected single bond length to the expected double bond length.

Haochen He 3L
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Joined: Wed Sep 30, 2020 9:37 pm

Re: bond length

Postby Haochen He 3L » Sun Nov 15, 2020 6:20 pm

Hi, I don't think we need to calculate the actual bond length. As long as you know some characters like the longer length the weaker strength, you should be fine.

Sarah Huang 3A
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Re: bond length

Postby Sarah Huang 3A » Sun Nov 15, 2020 6:23 pm

Tiffanny_Carranza_2D wrote:are we supposed to know how to calculate bond length?

if so what equation or how do we do that?
thank you


Hi Tiffany!

In this class, we do not need to calculate the actual bond length, as it is usually given, both the theoretical and the experimentally observed one. However, we will be asked on the average bond length of the molecule, and when that happens, you use the theoretical bond length that is given to you. For example, if they said that C-O is 164 pm and C=O is 143 pm (these are random numbers, not official ones), and you were told to calculate the average bond length, then you would add up the total bond length and divide it by the number of bonds. If you had 1 double bond and 2 single bonds, then you would write (2(164)+1(143)/3 because you have two single bonds and 1 double bond, making a total of three bonds. Go ahead and solve it.

If you got 157pm, then you are correct!

I know you may not have needed the example, but I really hope that clarifies with what we need to do in the class.

Rayna Irving 2C
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Joined: Wed Sep 30, 2020 9:33 pm

Re: bond length

Postby Rayna Irving 2C » Sun Nov 15, 2020 8:04 pm

No, I don't think we're expected to calculate bond length as of right now, just know certain trends and ideas like triple bonds are the shortest while single bonds are the longest, and the bigger atoms have longer bond lengths when bonded with another, etc.

Mari Williams 1K
Posts: 89
Joined: Wed Sep 30, 2020 9:53 pm

Re: bond length

Postby Mari Williams 1K » Sun Nov 15, 2020 8:50 pm

Do we need to know the relative lengths of other bonds like hydrogen bonds?

Algernon Jackson 2l
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Joined: Mon Jan 06, 2020 7:27 am

Re: bond length

Postby Algernon Jackson 2l » Sun Nov 15, 2020 8:53 pm

No, bond lengths are given.

nayha a 1E
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Joined: Wed Sep 30, 2020 9:54 pm

Re: bond length

Postby nayha a 1E » Sun Nov 15, 2020 8:59 pm

I don't think we need to calculate the exact bond lengths, but you should know the difference between the general bond lengths. Which ones are stronger and shorter vs. weaker and longer in regards to the single, double, and triple bonds.

Irene Nguyen 2J
Posts: 50
Joined: Wed Sep 30, 2020 9:44 pm

Re: bond length

Postby Irene Nguyen 2J » Sun Nov 15, 2020 9:19 pm

As others have mentioned, the bond length should be given to solve such. It's more important to know lengths in regards to the number of bonds, e.g Single bonds > Double bonds > Triple bonds.

joshtully
Posts: 92
Joined: Wed Sep 30, 2020 9:36 pm

Re: bond length

Postby joshtully » Sun Nov 15, 2020 9:26 pm

No, we do not need to calculate actual lengths.

Lauren Strickland 1B
Posts: 89
Joined: Wed Sep 30, 2020 9:47 pm

Re: bond length

Postby Lauren Strickland 1B » Sun Nov 15, 2020 9:28 pm

No I do not think we have to know how to calculate bond lengths.

Britney Tran IJ
Posts: 90
Joined: Fri Aug 30, 2019 12:18 am

Re: bond length

Postby Britney Tran IJ » Sun Nov 15, 2020 10:24 pm

nope but we do need to know the length of the bonds in regards to the number of bonds

Gustavo_Chavez_1K
Posts: 92
Joined: Wed Sep 30, 2020 9:46 pm

Re: bond length

Postby Gustavo_Chavez_1K » Sun Nov 15, 2020 10:48 pm

I do not think that we need to know how to calculate bond length necessarily. However, we should definitely be able to differentiate bond length based on the number of bonds. The higher the bond order (single bond, double bond, triple bond), the shorter the bond length.

Maryeli Garay 2H
Posts: 91
Joined: Wed Nov 13, 2019 12:18 am

Re: bond length

Postby Maryeli Garay 2H » Sun Nov 15, 2020 10:54 pm

I’m pretty sure we’re not gonna need to know how to solve for/calculate the bond length for the upcoming midterm!

Arnav Saud 2C
Posts: 117
Joined: Wed Sep 30, 2020 9:51 pm

Re: bond length

Postby Arnav Saud 2C » Sun Nov 15, 2020 11:01 pm

I don't think we'll need to calculate bond length for this midterm.

Brandon McClelland3L
Posts: 89
Joined: Wed Sep 30, 2020 9:31 pm

Re: bond length

Postby Brandon McClelland3L » Sun Nov 15, 2020 11:26 pm

We just need to be able to compare them, no exact numbers. Just know that double bonds are stronger than single bonds, and that larger molecules have weaker bonds.

Queena Chu 3E
Posts: 86
Joined: Wed Sep 30, 2020 10:09 pm

Re: bond length

Postby Queena Chu 3E » Sun Nov 15, 2020 11:27 pm

We don't need to know the exact numbers but we do need to know how to compare them in terms of strength and length.

sabrina ghalambor 2J
Posts: 98
Joined: Wed Sep 30, 2020 9:35 pm

Re: bond length

Postby sabrina ghalambor 2J » Sun Nov 15, 2020 11:29 pm

we won't need to know anything exact, but know that the order from longest to shortest goes single>double>triple

305572629
Posts: 86
Joined: Wed Sep 30, 2020 9:41 pm

Re: bond length

Postby 305572629 » Sun Nov 15, 2020 11:41 pm

no- all bond lengths in specific numbers should be given to us. If we ever have to figure out a bond length, just use a general periodic trend to make an estimate.

Jacob Schwarz-Discussion 3I
Posts: 81
Joined: Wed Sep 30, 2020 10:01 pm

Re: bond length

Postby Jacob Schwarz-Discussion 3I » Sun Nov 15, 2020 11:47 pm

No! You just need to know the concepts. For example, multiple bonds have a shorter bond length. Weaker bonds are longer. Lone pairs on neighboring atoms also repel each other, which then in turn weakens the bond.

Fernanda Olvera 3D
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Joined: Wed Sep 30, 2020 9:41 pm

Re: bond length

Postby Fernanda Olvera 3D » Sun Nov 15, 2020 11:47 pm

To my understanding, we don't need to.

Minh Nguyen 3A
Posts: 38
Joined: Wed Sep 30, 2020 9:36 pm

Re: bond length

Postby Minh Nguyen 3A » Sun Nov 15, 2020 11:48 pm

Here's hoping that all we need to know are the basic concepts behind bond length, which I'm pretty sure is the case.


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