Angles Less Than a Certain Value

(Polar molecules, Non-polar molecules, etc.)

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joanneyseung22
Posts: 31
Joined: Fri Sep 28, 2018 12:15 am

Angles Less Than a Certain Value

Postby joanneyseung22 » Sun Nov 18, 2018 8:38 pm

How could we explain why a bond angle is less than another given certain bond angle? For example, sulfite has 4 electron pairs arranged tetrahedrally and the bond angles are around 106 degrees - less than 109.5. What is the specific explanation for why this is so?

deepto_mizan1H
Posts: 65
Joined: Fri Sep 28, 2018 12:16 am

Re: Angles Less Than a Certain Value

Postby deepto_mizan1H » Sun Nov 18, 2018 8:45 pm

Often we can answer the less than values by determining the differences in repulsion compared to other examples of the same orientation, where greater repulsive force from a pair or atom will push the others accordingly. It depends on each unique compound.

Akhil Paladugu 3G
Posts: 30
Joined: Fri Sep 28, 2018 12:26 am

Re: Angles Less Than a Certain Value

Postby Akhil Paladugu 3G » Sun Nov 18, 2018 8:49 pm

The lone pair repulsion pushes the other bond electron pairs to form a smaller angle. That is why denote it [censored] less than 109.5

Alexandra Ortega 4D
Posts: 31
Joined: Wed Oct 03, 2018 12:17 am

Re: Angles Less Than a Certain Value

Postby Alexandra Ortega 4D » Sun Nov 18, 2018 8:50 pm

For molecules with bond angles less than 109.5, such as sulfite, we say that the lone pair exerts a stronger force on the other bonding angles and it pushes them down. For molecules with bond angles less than 109.5 that have bonds with different elements, such as CH3Cl, we say that since the bonds are with 3 different elements, the bond angles differ slightly. In both cases, the bond angles are not 109.5.

Sara Sadrolsadat 1G
Posts: 39
Joined: Fri Sep 28, 2018 12:16 am

Re: Angles Less Than a Certain Value

Postby Sara Sadrolsadat 1G » Sun Nov 18, 2018 8:51 pm

To add on to the previous reply, for example, a molecule with a tetrahedral shape that has all bonding pairs may have bond angles of 109.5, but replace one of those bonding pairs with a lone pair and the bond angles will decrease because lone pairs repel bonding pairs more than bonding pairs repel other bonding pairs. Moreover, lone pairs repel lone pairs the most.


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