Question

Hydrogen bonding exists in $$HF$$ but not in $$HCl$$ . Explain?

Answer 1

Hint: A hydrogen bond is an electrical attraction between a hydrogen ($$H$$ ) atom covalently linked to a more electronegative atom or group and another electronegative atom containing a single pair of electrons (the hydrogen bond acceptor) (Ac). The solid line signifies a polar covalent link, while the dotted or dashed line denotes the hydrogen bond in such an interacting system. The second-row elements nitrogen ($N$ ), oxygen ($O$ ), and fluorine ($F$ ) are the most common donor and acceptor atoms ($F$)

Complete answer:
Many of the unusual physical and chemical characteristics of $N$ , $O$, and $F$ compounds are due to the hydrogen bond. Water's high boiling point ($$100{}^{\circ }C$$) is due to intermolecular hydrogen bonding, as opposed to the other group $$16$$ hydrides, which have significantly weaker hydrogen bonds. Due to intramolecular hydrogen bonding, the secondary and tertiary architectures of proteins and nucleic acids are partial. It also plays a major function in the structure of synthetic and natural polymers.
Intermolecular and intramolecular hydrogen bonding are both possible. The energy of a hydrogen bond can range from $1$ to $$40kcal/mol$$ , depending on the nature of the donor and acceptor atoms that make up the bond, their shape, and the surrounding environment. This makes them a little stronger than a van der Waals interaction but not quite as strong as completely covalent or ionic connections. This kind of connection may be found in both inorganic and organic compounds, such as water and DNA and proteins. Hydrogen bonds are what hold things like paper and felted wool together, as well as what causes distinct sheets of paper to cling together after becoming wet and drying.
When electrons are transferred in a covalent link between atoms with differing electronegativities, the result is a polar covalent bond. Find the hydrogen chloride molecule ($$HCl$$). Each atom in $$HCl$$requires one additional electron to produce an inert gas electron configuration. The chlorine atom is far too hefty. The atom's size, in terms of electronegativity, is such that hydrogen bonds cannot form because the electron density is too low. This is why, whereas $$HF$$ exhibits hydrogen bonding, $$HCl$$does not.
Because chlorine is a big atom, the $$HCl$$has a high electronegativity value, but not enough to form a hydrogen bond. When hydrogen is linked to fluorine, oxygen, or nitrogen atoms, hydrogen bonds form. These are relatively tiny atoms that may form a connection with hydrogen.

Note:
These macromolecules fold into a particular form as a result of bonding between sections of the same macromolecule, which helps establish the molecule's physiological or biochemical purpose. The double helix shape of DNA, for example, is primarily owing to hydrogen bonding (as well as pi stacking interactions) between its base pairs, which join one complementary strand to the other and permit reproduction.