Increasing F-A-F Bond Angles: OF2, NF3, CF4, BeF3, BeF2

In summary, the conversation discusses arranging the AFn species (BeF3, BeF2, CF4, NF3, and OF2) in order of increasing F-A-F bond angles. The suggested order is OF2, NF3, CF4, BeF3, and BeF2. The conversation also mentions the importance of considering the effect of lone pairs on bond angles, which can vary between molecules.
  • #1
MysticDude
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Homework Statement


Another chemistry question :D
Arrange the following AFn species in order of increasing F-A-F bond angles: BeF3, BeF2, CF44, NF3, and OF2.

Homework Equations


The Attempt at a Solution


Ok so I'm thinking that it would be OF2 first because it's bent and both of the lone pairs decrease the bond angles by around 2° each, making them 105.5°.

Next should be NF3, the lone pair decreases the bond angle by 2° making it 107.5°.

Then I think that CF4 is next because it would angles around 109.5°.

Next one the list I chose BeF3 because the bond angles would be 120°.

Last I chose BeF2 because it is linear, making the bond angles 180°.

So in the end OF2 -> NF3 -> CF4 -> BeF3 -> BeF2

I hope that you can understand my logic and see if I'm right or wrong. Thanks for any help.
 
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  • #2
As far as I can see your methodology is correct and you seem to have the right answer. Just be careful and make sure how much the lone pairs decrease the bond angles for each distinct molecule because it can vary, for example 2 degrees for molecule A and 4 degrees for molecule B
 
  • #3
Okay thanks for the answer. This question is pretty old though and I'm already past the unit in the class.
 

What is the purpose of increasing F-A-F bond angles in OF2, NF3, CF4, BeF3, and BeF2?

The purpose of increasing F-A-F bond angles is to reduce the repulsion between the electron pairs on the fluorine atoms, making the molecules more stable and reducing the potential for bond distortion.

How is the F-A-F bond angle increased in these molecules?

The F-A-F bond angle is increased by replacing one or more of the fluorine atoms with a smaller, more electronegative atom such as oxygen or nitrogen.

Is there a specific range of F-A-F bond angles that is considered optimal?

Yes, the optimal range for F-A-F bond angles is between 109.5 degrees (the ideal angle for tetrahedral molecules) and 120 degrees (the ideal angle for trigonal planar molecules).

What effect does increasing the F-A-F bond angle have on the overall shape of the molecule?

Increasing the F-A-F bond angle can cause the molecules to become more linear or bent, depending on the number and placement of the electrons in the molecule.

How does the increase in F-A-F bond angle affect the physical and chemical properties of these molecules?

The increase in F-A-F bond angle can affect the polarity, melting and boiling points, and reactivity of these molecules. Generally, a larger F-A-F bond angle can lead to a more polar molecule with higher melting and boiling points, and increased reactivity due to the increased repulsion between the electron pairs.

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