Drawing the Lewis Structure for NI3

Viewing Notes:

  • NI3 is highly explosive when dry. When it explodes it produces a cloud of purple smoke (this is iodine gas). It is termed a "contact explosive" since it doesn't take much to set it off. Demonstrations will often use a feather to cause the explosion.
  • NI3 is very similar to NH3 and NF3.
  • For the NI3 Lewis structure there are a total of 26 valence electrons available.

Transcript: Hi, this is Dr. B. Let's do the Lewis Structure for NI3, Nitrogen Triiodide. That's one of Dr. B.'s favorite chemicals: big explosion, nice purple cloud. So let's look on the periodic table. Nitrogen is in Group 5, sometimes called fifteen, so it has five valence electrons. And then for Iodine we have seven valence electrons but there's three of them so 5 + 21 = 26 total valence electrons. Let's put Nitrogen in the center. It is the least electronegative. And then let's put some Iodines around the outside. We have three of them.

And so now that we've got that we can draw some electrons. We have 26. We'll start by forming the chemical bonds, right here, between atoms ... we've used six valence electrons. Now let's go around the outside: six, eight twelve, fourteen, sixteen, eighteen, twenty twenty-two, twenty four and then the last two. Let's see if we have octets. Each of the I's s has eight valence electrons so the octets are satisfied there. And then in the center the Nitrogen also has 8 valence electrons so those octets are satisfied. We've used all 26 valence electrons.

So that is the Lewis structure for NI3. You could also draw it like this right here as a structural formula. This is Dr. B., and thanks for watching.