As a subject matter expert in the field of physical chemistry, I can explain why hydrogen has a very low boiling point. The boiling point of a substance is determined by the strength of the intermolecular forces that hold its molecules together. Hydrogen, being the lightest element, has a very small molecular mass. This results in relatively weak intermolecular forces, specifically van der Waals forces, which are the forces of attraction between molecules that are not chemically bonded to each other.

The primary type of van der Waals force in hydrogen is the London dispersion force, which is the weakest of the van der Waals forces. It arises due to the temporary polarization of the molecule, which induces an instantaneous dipole that can attract other molecules. However, since hydrogen is a diatomic molecule (H2), it has a very small surface area and a low electron cloud density, leading to a minimal chance for these temporary dipoles to form and interact with each other.

Furthermore, the **induced dipole-induced dipole interactions**, another type of van der Waals force, are also weak in hydrogen due to its simple molecular structure and lack of polarizability. There are no permanent dipoles or induced dipoles in hydrogen molecules that would significantly enhance these interactions.

The orientation-dependent nature of hydrogen bonding, which is a stronger intermolecular force seen in some other molecules, is not present in hydrogen because it lacks the necessary molecular geometry and polarity to form hydrogen bonds.

The boiling point of a substance is the temperature at which the kinetic energy of its molecules is sufficient to overcome the intermolecular forces holding them in the liquid phase. Since the intermolecular forces in hydrogen are very weak, it doesn't take much energy for the hydrogen molecules to overcome these forces and transition from the liquid to the gaseous state. This is why hydrogen has one of the lowest boiling points of all the elements, at approximately -252.87 degrees Celsius.

In summary, the low boiling point of hydrogen can be attributed to its small molecular size, the absence of strong intermolecular forces like hydrogen bonds, and the presence of only weak London dispersion forces. The ease with which these weak forces can be overcome by the kinetic energy of the molecules at relatively low temperatures results in hydrogen's very low boiling point.

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Intermolecular forces. All of these substances have very strong covalent bonds between the atoms, but much weaker forces holding the molecules together. ... Because the weak intermolecular forces break down easily these substances have low melting and boiling points.read more >>