The shapes of nitrogen trifluoride and boron trifluoride??

As you may already know the shapes of nitrogen trifluoride and boron trifluoride is a trigonal pyramidal. However apparently the shape of nitrogen trifluoride is different to boron trifluoride. Can someone please explain to me why the shape of NF3 is different to BF3.

Thanks..

Reply 1

kinglrb

OP

12

actually I got the answer from a friend, thanks if you did read this.
here is the answer if anyone is intrested...
"The shape of the molecule depends on how many electrons and bonds you have in the outer shell of the central atom.
For NH3, N is the central atom. It has 3 covalent bonds and a lone pair. Thus the repulsion of the lone pair electrons and the bond electrons will force them to arrange at the corners of a tetrahedral. The molecule will look as a trigonal pyramid (since the lone pair is not "visible" in the structure.

For BH3, B is the central atom and has no lone pair apart from the three bonds. So the repulsion of the bond electrons will force them to be in a planar trigonal arrangement"

Reply 2

amyAcurran

Original post by kinglrb

actually I got the answer from a friend, thanks if you did read this.
here is the answer if anyone is intrested...
"The shape of the molecule depends on how many electrons and bonds you have in the outer shell of the central atom.
For NH3, N is the central atom. It has 3 covalent bonds and a lone pair. Thus the repulsion of the lone pair electrons and the bond electrons will force them to arrange at the corners of a tetrahedral. The molecule will look as a trigonal pyramid (since the lone pair is not "visible" in the structure.

For BH3, B is the central atom and has no lone pair apart from the three bonds. So the repulsion of the bond electrons will force them to be in a planar trigonal arrangement"