Question help!!!!

[Dr rice]

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Im taking the test on the 20th of june, in like two days. Im doing top score pro and I have been getting 19's on every test. I have a question that I don't understand.
which of the following has an octet on central atom

ICl+4
IF3
BrF4-
PBr4+

the solution says PBr4+ how in the %$& does this work.


Does anyone have any last minute tips for not flunking the DAT

 

[pbure9]

hmm strange. Should it be IF3, its got 10 e- on the Iodine???

and dude, I'll be there soon too. Just relax and get it done!
Best of luck to ya

 

[tdkyun]

You have to be able to draw lewis structures. P has 5 valence electrons and shares 4 to make 4 bonds with Br. Since it has a + charge, it has lost that extra electron. So total 4 electron pairs making 4 bonds satisfies the octet.

So basically look at your central atom and see how many electrons are around it.

 

[Sublimation]

Okay relax. Here is a way to do this. Octet means 8 electrons. Some atoms can go beyond i.e. P and S. Now for PF4+. P has 5 valence e-. Now if u bond 4 things to it u get 1 electron by itself. But since its a + charge just drop one of the electrons and u get 8. 5+4(from the F that you add) and -1 gives u 8.