Is Hydrogen Bonding Present in NH3?

Ammonia is a colourless, pungent-smelling gas that can be condensed into a liquid at low temperatures and pressure. It has the formula NH3 and is made up of one nitrogen atom linked to three hydrogen atoms.

It’s a common nitrogenous waste as well as a commercially relevant substance. It is formed both naturally and as a result of human activity. In concentrated form, ammonia can be dangerous. It dissolves easily in water.

We’ll look at whether NH3 molecules have hydrogen bonding in this article. So, let’s get this party started.

Is hydrogen bonding present in NH3? Yes, hydrogen bonds are formed by NH3. The intermolecular forces that operate between ammonia molecules are known as hydrogen bonding. Because of the electronegativity difference between nitrogen and hydrogen, nitrogen develops a partial negative charge, while hydrogen develops a partial positive charge. These charges are responsible for attracting and forming hydrogen bonds with nearby NH3 molecules.

Let’s take a closer look at this. Keep in touch.

What causes hydrogen bonds to form in NH3?

When a hydrogen atom is connected to an atom with a high electronegativity, hydrogen bonds are created.

In the NH3 molecule, nitrogen has an electronegativity of 3 while the hydrogen atom has an electronegativity of 2.2, resulting in a large negative difference between the two atoms.

Also, because the nitrogen atom has 5 electrons in its valence shell, it is left with one lone pair of electrons after associating with three hydrogen atoms.

The nitrogen atom pulls the shared pair of electrons towards itself due to the significant electronegativity difference between the two atoms, resulting in a partial negative charge on the nitrogen atom.

The hydrogen atom gains a little positive charge as electrons are pushed away from it.

Furthermore, the nitrogen atom possesses a lone pair of electrons, which increases the negative forces around it, causing the hydrogen atoms of the other ammonia molecules, which have a tiny positive charge, to be drawn to the nitrogen atom.

The creation of hydrogen bonds between various ammonia molecules is caused by the contact forces between the nitrogen atoms of one molecule and the hydrogen atoms of another ammonia molecule.

Intermolecular hydrogen bonding in NH3 molecules is caused by the electronegativity mismatch between hydrogen and nitrogen atoms, as well as the availability of a lone pair with nitrogen.

What is Hydrogen Bonding, and how does it work?

When hydrogen is connected to more electronegative atoms like nitrogen, oxygen, or fluorine, it forms a hydrogen bond, which attracts other molecules.

These forces are weaker than the ionic and covalent chemical bonds that normally develop between atoms.

The energy required to break the bonds is used to determine the strength, which is substantially lower in the case of hydrogen bonds.

However, if a combination contains a large number of hydrogen bonds, this might result in very strong forces.

The hydrogen bonds are generated as a result of an unequal charge distribution within a molecule, which is referred to as polarity.

The oxygen and nitrogen atoms, for example, are more electronegative than the hydrogen atoms linked to them in water and ammonia, respectively.

The creation of a partial negative charge on the more electronegative atom and a partial positive charge on the other atom is caused by the stronger electron affinity of nitrogen or oxygen atoms.

Hydrogen bonding occurs when the oppositely charged ends of two molecules of the same chemical become closer to each other, resulting in weak inter-molecular attraction forces between these molecules.

The electrostatic pull between the molecules causes these bonds to form, and they become more pronounced as the distance between the molecules decreases.

When a result, as the distance between the molecules reduces, the number of hydrogen bonds increases.

This is why water has the most hydrogen bonds in solid form and nearly none when it is present as a vapour.

Proteins, nucleic acids, and other vital biological components all rely on hydrogen bonding to function.

Is it true that NH3 and Water (H2O) form Hydrogen Bonds?

Hydrogen bonds are created between the molecules of a compound when hydrogen is bonded to a more electronegative atom such as nitrogen, fluorine, or oxygen, as detailed in the previous section.

In the case of water molecules, the oxygen atom, which is more electronegative, draws the bound pair of electrons towards itself and gains a partial positive charge, causing the hydrogen atom to gain a partial negative charge.

The oxygen atom also contains six valence electrons, which means that after making covalent connections with the two hydrogen atoms, it still retains two lone pairs of electrons that are responsible for creating a cloud of negative charge around it.

The attraction of hydrogen atoms from other water molecules and the formation of hydrogen bonds are due to this negative charge.

As a result, hydrogen bonds hold both ammonia and water molecules together.

Water, on the other hand, has a stronger hydrogen bond than ammonia because oxygen is more electronegative than nitrogen and possesses two lone pairs of electrons.

Because there aren’t enough lone pairs in the NH3 molecule to satisfy all of the hydrogen atoms with partial positive charges, ammonia quickly forms hydrogen bonds with water molecules when they’re combined together.

The fact that ammonia dissolves so easily in water is due to hydrogen bonding.

Why do NH3 and PH3 create hydrogen bonds but not PH3?

Both nitrogen and phosphorous are group 15 elements with five electrons in their valence shells, and they combine with three hydrogen atoms to generate their respective compounds, phosphorus phosphate and nitrogen ammonia.

Ammonia molecules, on the other hand, are joined together by hydrogen bonds, whereas phosphorus molecules do not.

The huge atomic radius of phosphorus is the cause for this. Taking a look at their electric setup:

[He] 2s22p3 Nitrogen (N)

[Ne] 3s23p3 phosphorus (P)

Because the electrons in nitrogen atoms are near to the nucleus, the atom has a high electronegativity, which is responsible for intermolecular hydrogen bonding in ammonia atoms.

The electrons of the phosphorous atom, on the other hand, are loosely linked since they are far out from the nucleus in the third orbital. As a result, the phosphorous atom has low electronegativity.

As a result, the phosphorous atom lacks a high electron affinity and hence is unable to attract electrons from the PH3 molecule.

Because the atoms do not develop partial charges, there are no electrostatic forces or negative charges to attract them from other molecules, and so no hydrogen bonds are created in the case of phosphine.

What causes hydrogen bonds to form?

The electronegativity differential between the hydrogen atom and the linked atom, such as nitrogen, oxygen, or fluorine, is the primary cause of hydrogen bond formation.

The element with a higher electron affinity draws the electron away from the hydrogen atom, giving it a slight negative charge while the hydrogen atom has a slight positive charge.

Furthermore, the atoms that form hydrogen bonds have a lone pair of electrons bonded to them, which increases the negative charge around the atom, attracting oppositely charged atoms from other molecules, resulting in the creation of hydrogen bonds due to electrostatic forces.

Hydrogen bonds, despite their weakness, are capable of holding the compound’s molecules together.

NH3’s Characteristics

The table below lists some of the most important features of hydrogen atoms:

Chemical NameAmmonia
Molecular formulaNH3
Molecular weight17.031 g/mol
AppearanceColorless gas
OdorPungent
Molecular GeometryTrigonal pyramidal
Melting Point−77.73 °C
Boiling Point−33.34 °C
Density0.86 kg/m3
Dipole moment1.42 D

NH3’s Applications

The following are some of the most important uses of ammonia:

• Fertilizers consume over 88 percent of the world’s ammonia production.

• Ammonia is used to make nitric acid, hydrazine, hydrogen cyanide, and urea, among other nitrogenous chemicals.

• Ammonia-water solutions containing 5-10% by weight are used as household cleaners, particularly for cleaning glasses.

• It’s also utilised for nitrogen-consuming bacteria in the fermentation industry.

• Ammonia is employed as an antibacterial agent because it is a strong antiseptic.

• Ammonia, which has about one-third the energy density of diesel, is also emerging as a possible fuel source.

• It’s also employed as a refrigerant gas and in air-conditioning systems.

• Paper, leather, and rubber are all industries that employ ammonia.

• It is also utilised in wastewater treatment.

Conclusion

The significant electronegativity gap between the nitrogen and hydrogen atoms causes intermolecular hydrogen bonding in ammonia molecules.

Because nitrogen is more electronegative, it has a strong electron affinity, drawing the shared pair of electrons to itself and gaining a partial negative charge, leading hydrogen to gain a partial positive charge.

Because of nitrogen’s partial negative charge and the lone pair of electrons placed above it, the positively charged atoms of the other molecules form weak intermolecular interactions known as hydrogen bonds.

Because hydrogen bonds occur between these molecules, ammonia is soluble in water.

Unlike the NH3 molecule, PH3 does not form a hydrogen bond because the atomic radius of phosphorous is much larger than that of nitrogen, making it unable to exert comparable electronegativity.

I believe I was able to explain the reasons for hydrogen bonding in NH3 molecules in detail.

Please share this post with your friends if you enjoyed it.

Thank you very much!!

Read more: Hybridization, Lewis Structure, and Molecular Geometry of H2SO4

Misha Khatri
Misha Khatri is an emeritus professor in the University of Notre Dame's Department of Chemistry and Biochemistry. He graduated from Northern Illinois University with a BSc in Chemistry and Mathematics and a PhD in Physical Analytical Chemistry from the University of Utah.

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