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### bond angles

Posted: Sat Dec 07, 2019 11:09 pm
Can someone explain how we knows what the bond angles are? I'm still confused about how we know that, or like how we know that an angle is less than some other angle(for example when they say that an angle is <120, how do they reach that conclusion)?

### Re: bond angles

Posted: Sat Dec 07, 2019 11:15 pm
Bond angles will be less than the ideal structure due to lone pair and bond pair repulsion and/or lone-pair lone-pair repulsions.

### Re: bond angles

Posted: Sat Dec 07, 2019 11:20 pm
Bond angles were covered in lecture and can also be found in the textbook. Bond angles are affected by repulsion between electrons, with stronger repulsions between lone pair and lone pair electrons and weaker repulsions between bonded pair and bonded pair electrons.

### Re: bond angles

Posted: Sun Dec 08, 2019 6:33 pm
Lone pairs will make a bond angle less than (<) the angle of the shape it is derived from, because the electron repulsion from lone pairs condenses the angles of the bonds.

### Re: bond angles

Posted: Sun Dec 08, 2019 6:47 pm
Bond angles will depend on electrons and the molecular shape. Lone pair electrons have greater repulsion than bonded electrons and will therefore create a smaller bond angle.

### Re: bond angles

Posted: Sun Dec 08, 2019 7:05 pm
bond angles will be dependent on the electron arrangement and determining if they are less than a certain angle will be the effect of lone pairs.

### Re: bond angles

Posted: Sun Nov 15, 2020 10:53 am
bonding angle is determined by the number of atoms in a molecule and the arrangement of atoms

### Re: bond angles

Posted: Sun Nov 15, 2020 2:43 pm
though the explanations make some sense, im still a bit confused in the process of finding the actual value of a bonding angle. can someone possibly explain an example? maybe one of the ones from lecture?

### Re: bond angles

Posted: Sun Nov 15, 2020 2:47 pm
If lone pairs have more repulsion power than a bond, how does a lone pair affect the bonding angles of a molecule? How would we calculate it?

### Re: bond angles

Posted: Sun Nov 15, 2020 9:54 pm
The bond angle will depend on the arrangement of electrons and molecular shape.

### Re: bond angles

Posted: Wed Nov 18, 2020 11:18 am
Bond angles can be generalized and predicted based on shape, but will slightly differ based on certain atoms. Also, lone pairs contain additional force which pushes bonding electron pairs closer together, making bond angles smaller. I do not think we have to be able to determine bond angles, but we should be aware what could make them smaller / be able to estimate based on shape.

### Re: bond angles

Posted: Wed Nov 18, 2020 11:26 am
We are not required to know the bond angles, but we are able to tell if the bond angle will be less. If there are lone pairs, it will "squish" the bond angles, making the angle smaller.

### Re: bond angles

Posted: Wed Nov 18, 2020 11:50 pm
I think we can predict the bond angles using the VSEPR theory, so for example how long-pairs repel each other more than lone-pairs repel a bonding pair. So if we have a lone-pair of electrons on the central atom we will know that the other atoms bonded to the central atom will be pushed down and the bond angles will change accordingly.

Hope it helps!

### Re: bond angles

Posted: Thu Nov 19, 2020 3:49 pm
We can predict the bond angles using VSPR, which is based on electron electron repulsion between lone pair electrons and bonding pair electrons. In terms of finding the exact value of the bond angles, this may not be always known, as many times the angles are described as being "less than" a certain amount, in which we do not need to know the exact angle.

### Re: bond angles

Posted: Thu Nov 19, 2020 6:13 pm
Guzman_1J wrote:Can someone explain how we knows what the bond angles are? I'm still confused about how we know that, or like how we know that an angle is less than some other angle(for example when they say that an angle is <120, how do they reach that conclusion)?

an angle may be smaller than 120 because there is a lone pair of electrons that will "push" the bonded electrons down and therefore, decrease the bond angles. the unpaired electrons have a negative charge that is repelling the electrons in the bonded pair, moving them and impacting the bond angle.Also remember lone pair electrons hold a larger volume in which that space has a negative charge. This is another factor that decreases bond angle

### Re: bond angles

Posted: Fri Nov 20, 2020 10:43 am
If there are lone pairs causing the bod angles to deviate from their average measurements, will the new angles always be less than their average counterparts?

### Re: bond angles

Posted: Fri Nov 20, 2020 12:57 pm
Professor Lavelle referenced in his lecture that repulsion strength goes in this order (LP-LP, LP-atom, atom-atom) thus the lone pairs will exert a bigger repulsive force on the other atoms making the other atoms get closer together (becomes less than 120 degrees or 109.5 what have you) so the LP can stay father apart.