## 3.61

vivianndo_1L
Posts: 30
Joined: Fri Apr 06, 2018 11:02 am

### 3.61

Can someone please explain to me why the Lewis structure of ICl4^-1 looks like this?

How is it determined that there are 2 lone pairs surrounding iodine?

Jared Pagal 1J
Posts: 24
Joined: Fri Apr 06, 2018 11:04 am

### Re: 3.61

There is a general rule when constructing lewis structures: any left over electrons usually are put on the central atom. Additionally, notice that Iodine has an expanded octet and can therefore accept those lone pairs.

Isabel Jabara 1C
Posts: 34
Joined: Fri Apr 06, 2018 11:03 am

### Re: 3.61

ICl4-1 has 36 valence electrons, but if you fill up all the octets there are still 4 left over. I is an exception to the octet rule so you can add lone pairs to it.

Yitzchak Jacobson 1F
Posts: 31
Joined: Wed Nov 22, 2017 3:00 am

### Re: 3.61

Hello, I believe since iodine is the least electronegative, it is centered in the middle. Also since it is an exception to the octet rule, you can add the excess lone pairs to it.
Really hope this helps :)

Heung Ching Chia 1E
Posts: 25
Joined: Mon Apr 09, 2018 1:38 pm

### Re: 3.61

ICl4- has 36 electrons in total. You first form a skeletal structure (with iodine (least electronegative atom) as your central atom)and so there are 4 single bonds connecting the iodine to each chlorine and that means you used up 8 electrons (28 e- left). You then add 6 electrons to each chlorine atom to form a complete octet because chlorine is more electronegative than iodine, so its pull on the electrons will be stronger and therefore you add the remaining electrons to chlorine first. You are then left with 28-(6*4)=4 electrons. The 4 electrons then go onto the central atom iodine as lone pair electrons. Iodine is an element after the 3rd period, so it can have an expanded octet.

Lastly, you can check formal charge to see if this is the best lewis structure.