Bond Angles

[Hayden Lee 1C]

Hi there,

For the final exam, will we be required to memorize the bond angles of certain molecular geometry? Thanks!

[SophiaBarden 2E]

Lavelle mentioned in his lectures that it will be important to remember the NAMES for bond angles of different structures (i.e. Linear, Trigonal Planar, Octohedral). Be able to recognize these patterns among molecules and look at the textbook example problems that lavelle assigns!

[Mansi Solanki 3A]

From what we are learning in lectures, I feel like it would be a good idea to know some of the bond angles for the most common molecular structures and then know that if a lone pair occurs in one of these structures then it will cause the bond angles to decrease from what they were in the structure with no lone pairs. I am not sure if we need to memorize the bond angles exactly though for all the structures.

[Karina Grover 1A]

Yes, I believe that you will have to memorize the bond angles. Most of them are pretty straightforward (180º, 90º, 120º, etc.), and the only difficult one is the bond angle of molecules with tetrahedral shape (109.5º). For molecules where a bonding pair is replaced by a lone pair, just remember that lone pairs tend to occupy a larger volume and thus affect the position of the bonding pairs. In consequence, the bond angles will be affected (less than 180º, slightly less than 109.5º, etc.). I hope this helps!

[Farah Abumeri 3F]

I think we just have to understand the patterns of bond angles and how bond angles change slightly based upon the number of lone pairs. If you have a basic understanding of for example, the tetrahedral arrangement, which has bond angles of 109.5, then you can adjust that number based upon how many electron density regions are lone pairs or atoms. The more lone pairs, the greater the electron repulsion, meaning the angle will be smaller than 109.5.

[Xinyu Li 1C]

I think we will need to know the bond angles for electron pair geometries (without lone pair), like 180, 120, 109, 90; and that having lone pairs influences the bond angles between bonded atom. But I doubt we will be required to memorize specific bond angles for different molecules.

[Jason Nguyen_1B]

For the final, you may have to memorize the bond angles of the basic molecular geometry, such as linear, trigonal planar, tetrahedral, trigonal bipyramidal, and octahedral geometry. However, for molecules with lone pairs, I think you just have to understand that the bond angles would be slightly less than molecules with the same electron density but no lone pairs.

[Gian Boco 2G]

I think it would be safe to know the bond angles with the common shapes and geomteries.

[Kandyce Lance 3E]

These responses are a bit mixed but I agree, it would be safest to memorize the basic bond angles in the common geometric shapes and planars

[Kandyce Lance 3E]

I have an additional question relating to bond angles, For two molecules with the same shape (like an AX_3 for example), will all the bond angles be the same? Or will they change depending on the individual elements?

[Kandyce Lance 3E]

I have an additional question relating to bond angles, For two molecules with the same shape (like an AX_3 for example), will all the bond angles be the same? Or will they change depending on the individual elements?

I understand bond angles with be slightly different with lone pairs vs no lone pairs, but besides that I wasn't entirely sure.

[Jaden Ji 2K]

I have an additional question relating to bond angles, For two molecules with the same shape (like an AX_3 for example), will all the bond angles be the same? Or will they change depending on the individual elements?

I understand bond angles with be slightly different with lone pairs vs no lone pairs, but besides that I wasn't entirely sure.

I think that the bond angles will be the same generally speaking, there could be some differentiation if there was a single electron around the atom. But it doesn't change drastically between different elements.

[Kandyce Lance 3E]

I have an additional question relating to bond angles, For two molecules with the same shape (like an AX_3 for example), will all the bond angles be the same? Or will they change depending on the individual elements?

I understand bond angles with be slightly different with lone pairs vs no lone pairs, but besides that I wasn't entirely sure.

I think that the bond angles will be the same generally speaking, there could be some differentiation if there was a single electron around the atom. But it doesn't change drastically between different elements.

Awesome thanks for clearing that up! :)

[Jeffrey Fenn 1G]

I think as long as you know the names you will be okay, I don't think we need to memorize how to draw them.

[Alexa Pham 1D]

Hi there,

For the final exam, will we be required to memorize the bond angles of certain molecular geometry? Thanks!

I believe that we have to have a good understanding on the molecular geometry of the different molecules. This will help us predict the bond angles rather than memorizing them. However, I think the bond angles we should know are 109.5 for tetrahedral shape, 120 for trigonal planar, and 180 for linear.

[Chance Herbert 3A]

I think Alexa put this very nicely. Knowing that bond angles 109.5° for tetrahedral shape, 120° for trigonal planar, and 180° for linear will definitely help in comparing molecules. I feel like these might be used as a reference for different molecules. For example, comparing an AX₄ to an AX₃E would allow you to predict that the second molecule (trigonal pyramidal molecular geometry) with a lone pair would have slightly smaller bond angles than the general tetrahedral since lone pairs exert a slightly greater repulsion than a bonding pair.

[Chance Herbert 3A]

Adding on to my last response, it would be impossible to know the bond angles for every molecule given that bonding atoms will have different properties that make their properties slightly different from the general bond angles; however, these values listed above give a great idea of understanding the general shapes of molecules with the same VSEPR formula.

[EnricoArambulo3H]

I think we would only have to actually memorize the basic bond angles for the arrangement of electron density regions (linear, trigonal planar, tetrahedral, trigonal bipyramidal, and octahedral). I think you should also know the effects of inserting a lone pair on the bond angles since sometimes a certain region will become a lone pair because it will maximize the bond angles between atoms. I hope this helped!

[Yijia_Yang_3A]

I think so because the sapling hw asked us to. However I think it is helpful to know conceptually what they are when compared.

[Lorraine Medina 3E]

I'm pretty sure we will have to memorize the shapes as well as the bond angles. Hope this helps!

[gabbi_r2C]

No, I don't think so. I remember Dr. Lavelle saying as much a few times during lecture, but you should know their relative bond angles (ie trigonal planar has a larger bond angle than tetrahedral) and how adding lone pairs would affect those relative bond angles.

[Juwan_Madaki_3K]

I think we will have to memorize the bond angels for shapes that have a consistent bond angles such as tetrahedral, trigonal planar, and linear. For other shapes, we most likely just need to know if it's above or below 120 degrees or 109.5 degrees.

[Cooper_Geralds_3B]

Here is a helpful summary of the molecular structures that we have done so far and their corresponding bond angles. Please feel free to add to this list!
-linear 180 degrees
-trigonal planar 120 degrees,
-trigonal pyramidal 109.5 degrees
-trigonal bipyramidal 90 degrees, 120 degrees
-octahedral 90 degrees
-square planar 90 degrees
-square pyramidal 90 degrees

[Becca Nelson 3F]

Yes. I do believe we will have to know the bond angles for the common geometries and we should be able to know how lone pairs impact these bond angles. We will have to know the general bond angle for that shape, but not the specific, experimentally derived values for each molecule.

[Vanessa Perez]

Here is a helpful summary of the molecular structures that we have done so far and their corresponding bond angles. Please feel free to add to this list!
-linear 180 degrees
-trigonal planar 120 degrees,
-trigonal pyramidal 109.5 degrees
-trigonal bipyramidal 90 degrees, 120 degrees
-octahedral 90 degrees
-square planar 90 degrees
-square pyramidal 90 degrees

thank you so much! very helpful

[105618850]

I do not remember him mentioning that we are required to memorize the bond angles, but I believe you should make an effort to familiarize yourself with which bond angles are associated with their respective molecular shapes.