a level chemistry

Which molecule is not able to form a co-ordinate bond with another species?
A) BH3
B )CH4
C )NH3
D )H2O
the answer is B but why cannot it be A as boron is group 3 so all the outer electrons are involved in bonding so no lone pairs therefore no dative covalent bond

(edited 5 months ago)

Reply 1

TypicalNerd

Original post by nnn121337

Try drawing a dot-and-cross diagram of BH3.

How many outer electrons are there in the boron and how many electrons should there be as a general rule of thumb?

It is also worth noting that for a coordinate bond to form in a reaction, one of your reactants must be a lone pair donor and the other must be a lone pair acceptor.

Reply 2

Emmaclems

Original post by TypicalNerd

Try drawing a dot-and-cross diagram of BH3.
How many outer electrons are there in the boron and how many electrons should there be as a general rule of thumb?
It is also worth noting that for a coordinate bond to form in a reaction, one of your reactants must be a lone pair donor and the other must be a lone pair acceptor.

Thanks lots for the explanation! I as well had no clue why the ans is what it is