NHF2 (fluorimide) has one nitrogen atom, one hydrogen atom, and two fluorine atoms. In the lewis structure of NHF2, there are three single bonds around the nitrogen atom, with one hydrogen atom and two fluorine atoms attached to it. Each fluorine atom has three lone pairs, and the nitrogen atom has one lone pair.
Here’s how you can draw the NHF2 lewis structure step by step.
Step #1: draw sketch
Step #2: mark lone pairs
Step #3: mark charges (if there are)
Let’s break down each step in detail.
#1 Draw Sketch
- First, determine the total number of valence electrons
Hence, nitrogen has five valence electrons, hydrogen has one valence electron, and fluorine has seven valence electrons.
Since NHF2 has one nitrogen atom, one hydrogen atom, and two fluorine atoms, so…
Valence electrons of one nitrogen atom = 5 × 1 = 5
Valence electrons of one hydrogen atom = 1 × 1 = 1
Valence electrons of two fluorine atoms = 7 × 2 = 14
And the total valence electrons = 5 + 1 + 14 = 20
- Second, find the total electron pairs
We have a total of 20 valence electrons. And when we divide this value by two, we get the value of total electron pairs.
Total electron pairs = total valence electrons ÷ 2
So the total electron pairs = 20 ÷ 2 = 10
- Third, determine the central atom
Here hydrogen can not be the central atom. Because the central atom is bonded with at least two other atoms, and hydrogen has only one electron in its last shell, so it can not make more than one bond.
Now we have to choose the central atom from nitrogen and fluorine. Place the least electronegative atom at the center.
Since nitrogen is less electronegative than fluorine, assume that the central atom is nitrogen.
Therefore, place nitrogen in the center and hydrogen and fluorine on either side.
- And finally, draw the rough sketch
#2 Mark Lone Pairs
Here, we have a total of 10 electron pairs. And three bonds are already marked. So we have to only mark the remaining seven electron pairs as lone pairs on the sketch.
Also remember that both (nitrogen and fluorine) are the period 2 elements, so they can not keep more than 8 electrons in their last shell. And hydrogen is a period 1 element, so it can not keep more than 2 electrons in its last shell.
Always start to mark the lone pairs from outside atoms. Here, the outside atoms are hydrogen and fluorines. But no need to mark on hydrogen, because hydrogen already has two electrons.
So for each fluorine, there are three lone pairs, and for nitrogen, there is one lone pair.
Mark the lone pairs on the sketch as follows:
#3 Mark Charges
Use the following formula to calculate the formal charges on atoms:
Formal charge = valence electrons – nonbonding electrons – ½ bonding electrons
For nitrogen atom, formal charge = 5 – 2 – ½ (6) = 0
For hydrogen atom, formal charge = 1 – 0 – ½ (2) = 0
For each fluorine atom, formal charge = 7 – 6 – ½ (2) = 0
Here, the atoms do not have charges, so no need to mark the charges.
And in the above structure, you can see that the central atom (nitrogen) forms an octet. Hence, the octet rule is satisfied.
Therefore, this structure is the stable lewis structure of NHF2.
Next: CH3CH2Cl Lewis Structure