IF7 (iodine heptafluoride) has one iodine atom and seven fluorine atoms. In the lewis structure of IF7, there are seven single bonds around the iodine atom, with seven fluorine atoms attached to it, and on each fluorine atom, there are three lone pairs.
Here’s how you can draw the IF7 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, both iodine and fluorine have seven valence electrons.
Since IF7 has one iodine atom and seven fluorine atoms, so…
Valence electrons of one iodine atom = 7 × 1 = 7
Valence electrons of seven fluorine atoms = 7 × 7 = 49
And the total valence electrons = 7 + 49 = 56
- Second, find the total electron pairs
We have a total of 56 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 = 56 ÷ 2 = 28
- Third, determine the central atom
We have to place the least electronegative atom at the center.
Since iodine is less electronegative than fluorine, assume that the central atom is iodine.
Therefore, place iodine in the center and fluorines on either side.
- And finally, draw the rough sketch
#2 Mark Lone Pairs
Here, we have a total of 28 electron pairs. And seven I — F bonds are already marked. So we have to only mark the remaining twenty one electron pairs as lone pairs on the sketch.
Also remember that iodine is a period 5 element, so it can keep more than 8 electrons in its last shell. And fluorine is a period 2 element, so it can not keep more than 8 electrons in its last shell.
Always start to mark the lone pairs from outside atoms. Here, the outside atoms are fluorines.
So for each fluorine, there are three lone pairs, and for iodine, there is zero lone pair because all twenty one electron pairs are over.
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 iodine atom, formal charge = 7 – 0 – ½ (14) = 0
For each fluorine atom, formal charge = 7 – 6 – ½ (2) = 0
Here, both iodine and fluorine atoms do not have charges, so no need to mark the charges.
And in the above structure, you can see that the central atom (iodine) forms an octet. Hence, the octet rule is satisfied.
Therefore, this structure is the stable lewis structure of IF7.
Next: HOF Lewis Structure