How?

[kristinalaudis3e]

How do I know if it will actually bond to make a coordinate covalent bond? I understand that one accepts the pair and one donates the pair, but how do you know if it will willingly donate?

[Marcus Lagman 2A]

Hello!

I believe a Lewis base will willingly donate its electrons if it still has available electrons for bonding. For example, NH3 is a Lewis base that will donate its electrons to a Lewis acid because it has a lone pair that its willing to donate. From these lone pairs, it's assumed that it will donate because of its availability.

I hope this makes sense. If anyone has a better explanation, I would appreciate it!

[David Chibukhchian 2G]

I agree with the other answer and would like to add that coordinate covalent bonds often form whenever the Lewis acid has an atom with an incomplete octet. An example is BF3. Because boron has an incomplete octet in this molecule, we can assume that it will in fact willingly accept the electron pair from the Lewis base that approaches it. That's how I think of it, I hope that helps!

[Kaihan_Danesh_2J]

It depends on the dipole moment of the molecules. If there is a molecule with a lone pair and a slightly negative charge on the atom with the lone pair, that atom will likely make a coordinate covalent bond with another molecule in which the central molecule has a slightly positive charge. So, it is based on lone pairs and dipole moment and where those two things are in the molecule.