The Student Room Group

Shapes of molecules

When a lone pair is involved in a dative covalent/ coordinate bond with another atom is it then considered as a bonding pair (when considering the shape of the moelcule?)
For example I thought the F-B-F angle in H3NBF3 would be 107 (trigonal) because there are 3 bonding pairs around the central B atom, and one lone pair, however it is 109.5, implying a tetrahedral shape and that the central atom has 4 bonding pairs around it.

I hope that makes sense!
H3NBF3? Which is the central atom?
Original post by annaj97
When a lone pair is involved in a dative covalent/ coordinate bond with another atom is it then considered as a bonding pair (when considering the shape of the moelcule?)
For example I thought the F-B-F angle in H3NBF3 would be 107 (trigonal) because there are 3 bonding pairs around the central B atom, and one lone pair, however it is 109.5, implying a tetrahedral shape and that the central atom has 4 bonding pairs around it.

I hope that makes sense!


Original post by annaj97
When a lone pair is involved in a dative covalent/ coordinate bond with another atom is it then considered as a bonding pair (when considering the shape of the moelcule?)
For example I thought the F-B-F angle in H3NBF3 would be 107 (trigonal) because there are 3 bonding pairs around the central B atom, and one lone pair, however it is 109.5, implying a tetrahedral shape and that the central atom has 4 bonding pairs around it.

I hope that makes sense!


The basic shape (before VSEPR distortions) adopted by the electron domains around any atom is only dependent on the number of domains.

Four domains = tetrahedral
Reply 4
Original post by zetamcfc

Thank you!!
Reply 5
Original post by charco
The basic shape (before VSEPR distortions) adopted by the electron domains around any atom is only dependent on the number of domains.

Four domains = tetrahedral


Thank you!!

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