Hi, the 2 conditions given for hydrogen bonding are:
1) A hydrogen atom must be covalently bonded to O, N or F atom. I can understand this part, as O, N and F are highly electronegative and will leave the H with a positive dipole (more or less a H+ ion).
2) The other condition is that the atom with a lone pair which the H is hydrogen-bonded to must be O, N or F. I don't get this part, though. Why can't it be any atom with a lone pair? Is it because O, N and F are highly electronegative and so the lone pair will not be donated directly to the H but will be held on tightly by the O, N or F and form a bond based on electrostatic forces of attraction instead of covalent bond?