NH3, also called ammonia, is a colorless gas and is made up of three hydrogen molecules and one nitrogen atom. It typically exists in the gaseous state at room temperature.
Ever wondered about that distinctive pungent smell lingering around your chemistry laboratory’s fume hood? Well, that unmistakable odor belongs to ammonia, represented by the chemical formula NH3.
Ammonia is not just a bad-smelling gas; it holds crucial chemical properties and serves various practical purposes. This article delves into a fundamental aspect of NH3: its polarity.
So, is ammonia (NH3) polar or nonpolar? Read on to find out.
What is NH3?
NH3, also known as ammonia, is a colorless gas with a pungent odor. It is composed of one nitrogen atom and three hydrogen atoms, with a chemical formula of NH3.
The molecule has a trigonal pyramidal shape, with the nitrogen atom at the apex and the three hydrogen atoms forming the base. The bond angle between the nitrogen and hydrogen atoms is approximately 107 degrees.
Ammonia has a melting point of -107.91°F (-77.73°C) and a boiling point of -28.01°F (-33.34°C). It is highly soluble in water due to its polarity, which makes it useful in many chemical reactions. The molecular weight of NH3 is 17.03 g/mol.
Ammonia forms when nitrogen (N) bonds with three hydrogen (H) atoms through single covalent bonds. Nitrogen has a pair of nonbonding electrons, influencing polarity and creating localized negative charges.
This lone pair of nitrogen pushes the bonds outward, resulting in a trigonal pyramidal structure. NH3‘s asymmetry makes it a polar molecule with a net dipole moment.
Factors that determine polarity
Polarity is a measure of the separation of electric charges in a molecule. The polarity of a molecule is determined by the difference in electronegativity between the atoms in the molecule. The greater the difference in electronegativity, the more polar the molecule.
The following are some factors that determine the polarity of a molecule:
Electronegativity
Electronegativity is the ability of an atom to attract electrons towards itself. The greater the difference in electronegativity between the atoms in a molecule, the more polar the molecule.
Molecular geometry
The shape of a molecule also plays a role in determining its polarity. If the molecule is symmetric, it will be nonpolar, even if it contains polar bonds. If the molecule is asymmetric, it will be polar.
Electric dipole moment
A dipole moment is a measure of the separation of positive and negative charges in a molecule. If a molecule has a dipole moment, it is polar. If it does not have a dipole moment, it is nonpolar.
Solvent
The polarity of a solvent can also affect the polarity of a molecule. A polar solvent will dissolve polar molecules, while a nonpolar solvent will dissolve nonpolar molecules.
Temperature
Temperature can also affect the polarity of a molecule. As the temperature increases, the polarity of a molecule decreases.
What is the polarity of NH3?
NH3 is a polar molecule. This is because of its asymmetrical shape, trigonal pyramidal structure, and the difference in electronegativities of nitrogen (3.04) and hydrogen (2.2).
The charges over the nitrogen and hydrogen atoms are unequally distributed, which results in a net dipole moment making NH3 a polar molecule.
According to the VSEPR theory, the lone pair on nitrogen exerts an outward force on the bonds, creating an unsymmetrical shape for NH3. This lone pair-bond pair repulsion plays a crucial role in shaping the molecule.
It’s worth noting that this polarity has implications in various contexts, influencing NH3‘s behavior in chemical reactions, its role in atmospheric processes, and even its presence in our bodies where the kidneys release ammonia to balance acidity.
Is NH3 an ionic or covalent molecule?
NH3 is a covalent molecule. This is because it is composed of non-metal atoms that share electrons to form covalent bonds.
In a covalent bond, two atoms share a pair of electrons. In the case of NH3, the nitrogen atom shares three electrons with the three hydrogen atoms, forming three covalent bonds.
The sharing of electrons in a covalent bond results in a stable molecule. In contrast, an ionic bond is formed when one atom donates an electron to another atom, resulting in the formation of ions. Ionic compounds are typically composed of a metal and a non-metal.
In ammonia, the bonding between nitrogen (N) and hydrogen (H) involves the sharing of electrons. Nitrogen and hydrogen share electrons through three covalent bonds, resulting in a molecular structure where the atoms are held together by shared electron pairs.
This sharing of electrons is characteristic of covalent molecules, which distinguishes NH3 as a covalent compound rather than an ionic one.
NH3 polarity and its solubility in water
NH3, as stated earlier, is a polar molecule. The polarity of NH3 makes it highly soluble in water. This is because water is a polar molecule, and “like dissolves like”.
The partial positive charge on the hydrogen atoms of NH3 is attracted to the partial negative charge on the oxygen atom of water, while the partial negative charge on the nitrogen atom of NH3 is attracted to the partial positive charge on the hydrogen atoms of water.
The solubility of NH3 in water can be represented by the following equation:
NH3 + H2O ⇌ NH4+ + OH–
In this equation, NH3 reacts with water to form ammonium ions (NH4+) and hydroxide ions (OH–). The reaction is reversible, and the extent of the reaction depends on the concentration of NH3 and the pH of the solution.
Higher NH3 concentrations and alkaline conditions favor the formation of ammonium ions (NH4+) and hydroxide ions (OH–).
The polarity of NH3 also makes it useful in many chemical reactions. For example, NH3 is a good nucleophile, meaning that it can donate a pair of electrons to another molecule. This makes NH3 useful in the synthesis of amino acids and the production of fertilizers.
How does the polarity of NH3 affect its reactions?
The polarity of NH3 affects its reactions in several ways. For example, the polarity of NH3 makes it a good nucleophile, meaning that it can donate a pair of electrons to another molecule.
This makes NH3 useful in many chemical reactions, such as the synthesis of amino acids and the production of fertilizers.
NH3 can react with acids to form ammonium salts. For example, when NH3 reacts with hydrochloric acid (HCl), it forms ammonium chloride (NH4Cl):
NH3 + HCl → NH4Cl
NH3 can also react with acids to form ammonium ions. For example, when NH3 reacts with sulfuric acid (H2SO4), it forms ammonium sulfate ((NH4)2SO4):
2NH3 + H2SO4 → (NH4)2SO4
Ammonia can also react with aldehydes and ketones to form imines. For example, when NH3 reacts with formaldehyde (HCHO), it forms methenamine (CH2O)6N4:
4NH3 + 6HCHO → (CH2O)6N4 + 6H2O
In addition, NH3 can react with metal ions to form complex ions. For example, when NH3reacts with copper(II) ions (Cu2+), it forms a deep blue complex ion:
Cu2+ + 4NH3 → [Cu(NH3)4]2+
FAQs
Is NH3 a polar covalent bond?
Yes, NH3 has a polar covalent bond. The N-H bond is polar because of the difference in electronegativity values of nitrogen (3.04) and hydrogen (2.2).
The unsymmetrical shape of the molecule results in an asymmetrical distribution of bonding electrons in the molecule, making NH3 a polar molecule.
Why is NH3 stable?
NH3 is stable because of its covalent bond between nitrogen and hydrogen atoms. The bond is formed by sharing three electrons of nitrogen and hydrogen atoms, leaving behind one lone pair on the nitrogen atom.
The bond is strong and stable because of the overlap of atomic orbitals of nitrogen and hydrogen atoms.
Which is more polar, HCl or NH3?
NH3 is more polar than HCl. The polarity of a molecule depends on the difference in electronegativity values of the atoms forming the bond.
The difference in electronegativity values of nitrogen and hydrogen atoms in NH3 is 0.84, while the difference in electronegativity values of hydrogen and chlorine atoms in HCl is 0.9. Therefore, NH3 is more polar than HCl.
Why is CHCl3 more polar than NH3?
CHCl3 (chloroform) has a higher polarity than NH3 because it is a larger molecule and has a higher electronegativity difference. The higher the electronegativity difference, the larger the magnitude of the dipole moment and the higher the polarity.
Why is NH3 polar and BF3 non-polar?
NH3 is polar, while BF3 is non-polar. NH3 is polar because of its asymmetrical shape, trigonal pyramidal structure, and different electronegativities of nitrogen and hydrogen atoms.
The charges over the nitrogen and hydrogen atoms are unequally distributed, resulting in a net dipole moment. On the other hand, BF3 is non-polar because of its symmetrical planar shape and equal distribution of charges over the boron and fluorine atoms.
Conclusion
In summary, NH3 is a polar molecule with a trigonal pyramidal molecular geometry. Its polarity makes it highly soluble in water and useful in many chemical reactions. Understanding the polarity of NH3 is important for understanding its properties and applications.
In addition, the polarity of NH3 affects its reactions in several ways. NH3 can react with acids to form ammonium salts and ammonium ions. It can also react with aldehydes and ketones to form imines and with metal ions to form complex ions.
The polarity of NH3 makes it a good nucleophile, which makes it useful in many chemical reactions.
You should also learn about the polarity of CCl4.
Thanks for reading.