[pop000]

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.

[DrBob1]

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.

[pop000]

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.


Thanks.

[Unknown008]

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:



+ 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]

[pop000]

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

[DrBob1]

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.

[pop000]

COOL thank you :)