Gen chem question (bond angle)

[alanan84]

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What set of species is arranged in order of increasing O-N-O bond angle?

A) NO2-, NO2, NO2+
B) NO2, NO2-, NO2+
C) NO2+, NO2, NO2-
D) NO2, NO2+, NO2-

 

[joonkimdds]

NO2+ is 180 degree so it has to be the biggest.
I am not sure about the other two.

 

[bebebebebebe]

NO2+, NO2, NO2-

First draw the NO2 lewis structure. You will have 1 unpaired electron on Nitrogen. (The total valence electrons is odd= 17). The molecule is in fact bent. Think about the unpaired electron as 1 electron domain, plus other 2 bonds, you will have the total of 3 for electron domains. Therefore the hybrid for Nitrogen is sp2, and the ideal bond angle is 120, BUT
the one lone electron exerts a less repulsion than normal on the two bonding oxygen atoms so they are able to spread out more to a 134 bond angle from the ideal of 120.
For NO2-, again the molecule is bent with the ideal of 120. But here you have 1 lone PAIR on nitrogen. They will take up more space than 1 unpaired electron or bonding electrons. That makes the bond around 115. You don't have to know the exact degree, as long as you know the bond angle of NO2 is larger than NO2-, it would be enough.

Now for NO2+, the molecule is linear. The total valence es is 16. That makes nothing left on nitrogen atom. The ideal angle for linear is 180.

 

[Shingo123]

NO2+, NO2, NO2-

First draw the NO2 lewis structure. You will have 1 unpaired electron on Nitrogen. (The total valence electrons is odd= 17). The molecule is in fact bent. Think about the unpaired electron as 1 electron domain, plus other 2 bonds, you will have the total of 3 for electron domains. Therefore the hybrid for Nitrogen is sp2, and the ideal bond angle is 120, BUT
the one lone electron exerts a less repulsion than normal on the two bonding oxygen atoms so they are able to spread out more to a 134 bond angle from the ideal of 120.
For NO2-, again the molecule is bent with the ideal of 120. But here you have 1 lone PAIR on nitrogen. They will take up more space than 1 unpaired electron or bonding electrons. That makes the bond around 115. You don't have to know the exact degree, as long as you know the bond angle of NO2 is larger than NO2-, it would be enough.

Now for NO2+, the molecule is linear. The total valence es is 16. That makes nothing left on nitrogen atom. The ideal angle for linear is 180.

Isnt that in order of decreasing bond angle?

 

[bebebebebebe]

Isnt that in order of decreasing bond angle?

Question says: increasing order ( I know I always suck at these kinda questions😀; get them right but choose the wrong answer!!)

What I meant:
NO2+( 180) > NO2 ( ~134) > NO2- (~ 115)

I think when it says "increasing order", they mean the first one is the largest or highest. Correct me if I am wrong?

 

[Shingo123]

Question says: increasing order ( I know I always suck at these kinda questions😀; get them right but choose the wrong answer!!)

What I meant:
NO2+( 180) > NO2 ( ~134) > NO2- (~ 115)

I think when it says "increasing order", they mean the first one is the largest or highest. Correct me if I am wrong?

When they say increasing order they mean, start from the smallest angle and then go to the largest. Think about it this way, as you go along the list the angles should be increasing.

Your deduction is correct, but the answer is exactly wrong 🙂

 

[bebebebebebe]

When they say increasing order they mean, start from the smallest angle and then go to the largest. Think about it this way, as you go along the list the angles should be increasing.

Your deduction is correct, but the answer is exactly wrong 🙂

Gotcha🙂 smallest to greatest. Now I feel stupid!! haha