Question

Although nitrogen and chlorine have the same electroncgativity, nitrogen atoms form stronger hydrogen bonds than chlorine atoms. This is due to (1) the basic character of nitrogen (2) the smaller size of nitrogen (3) the lesset number of electrons in the nitrogen atom (4) the inertness of nitrogen atom

Short answer

The smaller size of nitrogen (2) allows it to form stronger hydrogen bonds.

Step-by-step solution

Understanding Electronegativity

Both nitrogen and chlorine have the same electronegativity, meaning they attract electrons equally well. This sets up a control for comparing other properties.

Analyzing Hydrogen Bond Strength

Hydrogen bonds are a type of dipole-dipole interaction between molecules where hydrogen is bonded to a highly electronegative atom like nitrogen, oxygen, or fluorine. The strength of these bonds is influenced by the size of the atom bonded to hydrogen.

Comparing Atomic Sizes

Nitrogen is smaller in size compared to chlorine. This smaller size allows the nitrogen atom to come closer to the hydrogen atom, resulting in a stronger interaction or a stronger hydrogen bond.

Conclusion

Given the same electronegativity, the size of nitrogen allows it to form stronger hydrogen bonds compared to chlorine. None of the other factors listed (basic character, number of electrons, inertness) directly affect hydrogen bond strength as significantly as atomic size.

Key concepts

Electronegativity

Electronegativity is a measure of an atom's ability to attract shared electrons in a chemical bond. Both nitrogen and chlorine have the same electronegativity, which means they attract electrons with equal strength.
This property is crucial because it sets up a consistent basis for comparing other characteristics.
Electronegativity plays a significant role in the formation of bonds, particularly hydrogen bonds, where a hydrogen atom is attracted to a highly electronegative atom like nitrogen, oxygen, or fluorine.
High electronegativity helps in creating partial positive and negative charges, which are essential for dipole-dipole interactions. However, despite having the same electronegativity, nitrogen and chlorine exhibit different bonding behaviors due to other factors such as atomic size.

Atomic Size

Atomic size refers to the distance from the nucleus to the outermost electron shell. Nitrogen is smaller in atomic size compared to chlorine.
This smaller size is beneficial in forming stronger hydrogen bonds.
Because nitrogen is smaller, it can come closer to the hydrogen atom in another molecule, leading to a stronger interactive force.
Therefore, even though nitrogen and chlorine have equal electronegativity, nitrogen’s smaller atomic size allows it to form much stronger hydrogen bonds.
This is why atomic size is a critical factor when considering the strength of hydrogen bonds.

Dipole-Dipole Interaction

Dipole-dipole interactions occur between polar molecules. These interactions involve the attraction between the positive end of one molecule and the negative end of another.
Hydrogen bonds are a specific type of dipole-dipole interaction where hydrogen is bonded to electronegative atoms like nitrogen, oxygen, or fluorine.
The partial positive charge on the hydrogen atom of one molecule is attracted to the partial negative charge on the electronegative atom of another molecule.
In the case of nitrogen, its smaller size and the presence of lone pairs create a strong dipole, enhancing hydrogen bond formation.
This makes nitrogen a key player in dipole-dipole interactions, especially in biological molecules like DNA and proteins.

Nitrogen

Nitrogen is an essential element in many organic and inorganic compounds. It is found in amino acids, proteins, and nucleic acids.
Because of its high electronegativity and small atomic size, nitrogen forms strong hydrogen bonds, which are crucial in the structure and stability of biological molecules.
Despite having the same electronegativity as chlorine, nitrogen forms stronger hydrogen bonds due to its smaller atomic size, allowing for closer and more effective interactions.
Nitrogen's ability to form strong hydrogen bonds makes it vital in various chemical and biological processes, emphasizing its role beyond simple electronegativity considerations.