I need to draw the Lewis structure of KBF4
But I am not understand how B can be bound to 4 F atoms if it has only 3 Valence electrons?

In the picture you can see my direction I know is incorrect so I need help how to keep on from here.


Thanks. http://p1cture.me/images/62002452779010191790.jpg

Put the single electron on K onto the fluorine atom, making it a fluroide ion.
How many elecrons does it take to form a bond? Two, righ? Well the F- ion has four pairs, any of which can add to the BF3 molecule to form the BF4- ion. This is a classic Lewis acid/base reaction. Look at this in your textbook.

HI. Thank you for answering can you Please tell me if I get closer?
I Put the single electron on K onto the fluorine atom, making it a fluroide ion.
http://p1cture.me/images/04550208474310130500.jpg

Thanks.

I don't know the exact expectation when teachers ask for the lewis structure (we don't use this term here), but I would do it like this:

http://p1cture.me/images/08935347002282675440.png

+ is the outermost electron of B
Black square is the outermost electron of F
White square is the electron of K.

[zooming in the link of the image s clearer since I made them in pixels]

OK I will show this picture to my teacher and I will see what she will say.
Thanks a lot about this answer.

Unknown008 has given you the correct Lewis dot formula for potassium tetrafluoroborate. There are a couple of comments that can be made to the question and answers. A) in pop000's structure you should show the + charge on the K+ ion and the - charge on BF4-. B) pop000's structure shows the bonding electron pairs as lines -, this is fine but they are most often shown as the usual electron pairs : . Artistic license! I can't see for sure, but it looks like there might be a line as well as a dot; it should be one or the other.
C) Unknown008 has show the electrons from each source (K. F, BF3) with a differen notation. This is fine, I often do it myself to make sure the students can better visualize the structure, but you can also show all the electrons as dots. Well done by all of you.

COOL thank you :)