Question

Why is hydrogen bonding (except ion) the strongest intermolecular force? Give a brief explanation in 1 - 2 sentences. Note: drawing structures (bonds) helps. (4 pts)

Answer 1

hydrogen bonding is the strongest intermolecular force.Because, this strong intermolecular force is due to a strong dipole-dipole force .

Other bonds e.g. dipole dipole, van der waals…etc are dependent on electron arrangement at a given time and coincidence. E.g. one side of the atom may have more electrons by coincidence and therefore the other side is more positive. This would attract other atoms that are slightly negative on one side of the atom- also by coincidence. These fluctuating movements of electrons dont last long as they spin so fast and therefore the atoms begin to dissociate and do not require much energy to do so.

A hydrogen bond is a special type of attractive interaction (perhaps a variation of a dipole-dipole bond) that exists between an electronegative atom and a hydrogen atom bonded to another electronegative atom. This type of bond always involves a hydrogen atom, thus the name. Hydrogen bonds can occur between molecules (intermolecularly), or within different parts of a single molecule (intramolecularly). The typical hydrogen bond is stronger than van der Waals forces, but weaker than covalent or ionic bonds.

Example

H-bonding in H2O

So with water, H2O. The oxygen has two lone pairs of electrons and on top of this it is partially negative, making the hydrogen partially positive. The hydrogen bond is the bond formed from an oxygen atom in one molecule to a hydrogen atom in another molecule. Each oxygen has two hydrogen bonds while each hydrogen has one hydrogen bond. Hydrogen bonds happen with other covalent molecules with an electronegative atom. Like ammonia, NH3 and hydrogen fluoride, HF.