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Bond angles in NH3 and NF3 & VSEPR theory?
I was trying to figure out if the bond angles in NF3 are larger than in NH3. My reasoning led me to the conclusion that they should be larger, though in reality the opposite is true (102 deg for NF3 and 106 deg for NH3). I can't pinpoint where I am mistaken.
Here is my reasoning:
According to VSEPR the repulsion for lone pair-bond e (electrons) is greater than bond e- bond e. Thus the bond angles will be determined by the strength of the lone-pair-bond e repulsion. F is more electronegative, thus it will pull closer to it the bond electrons, reduce the electron cloud density near N, reduce the repulsion lone-pair-bond e, thus decrease the lone pair-bond e angle and increase the bond e- bond e angle.
What am I missing?
3 Answers
- 1 decade agoFavorite Answer
Electron cloud of N-F bonds will pull closer to N as you reasoned... However -- this will reduce the overall repulsion between the N-F bonds! Thus, the repulsion from the lone pair-bond e will (in essence) be greater)and will tend to push N-F bonds closer togehter -- thereby reducing the bond angle for NF3.
- 4 years ago
The nearer that the lone pair is to the nitrogen, the greater area that is going to take up in terms of the attitude, forcing the bonded electrons nearer to one yet another. Lone pairs around atoms take up greater area than bonded pairs. think of of it like a string tied at basically one end and a string tied at 2 ends. The string tied down at 2 ends (a bonded pair) has little room to return and forth, mutually as the string basically held at one end (the lone pair) can flow everywhere.
- 5 years ago
In N-F bond electron cloud stays farther to N atom (Closer to F atom). So all three N-F electron clouds stay away in distance and stay less crowded near N atom and thus push less on each other N-F bonds. So they stay closer at 102° bond angle.
In N-H bond electron cloud stays closer to N atom (farther from H atom). So all three N-H electron clouds stay very closer and stay more crowded near N atom and thus push more on each other N-H bonds. So they stay farther at 107° bond angle.
