Is Ammonia (NH3) ionic or covalent? Types of bond in NH3
Ammonia appears as colorless gas and has a strong pungent odor having chemical formula NH3. It is made up of one nitrogen and three hydrogen atom. It is one of the important sources of nitrogen for plants and animals. Exposing to open air, liquid ammonia will quickly turn into a gas. Ammonia is easily liquified due to strong hydrogen bonding between molecules.
In this article, we will discuss Is Ammonia (NH3) ionic or covalent? Bond types in ammonia, etc.
So, Is NH3 ionic or covalent? Ammonia (NH3) is a covalent compound. Because the bond is formed between one nitrogen and three hydrogen atom by the sharing of electrons. Also, the difference of electronegativity between nitrogen (N) and hydrogen (H) atoms on the Pauling scale is not big enough to make an ionic bond in the NH3 compound.
Let’s read in detail, why NH3 is a covalent compound? How covalent bonds formation takes place in NH3?
A covalent compound is a chemical compound that is made when two nonmetals or two p-block elements together share their valence electron with each other to complete the octet and attain stability.
The sharing of valence electrons between two atoms makes a bond which is called a covalent bond. “Valence electrons are the outermost shell electron of an atom”.
Ammonia (NH3) is a covalent compound. Because the nitrogen (N) and hydrogen (H) atoms are nonmetals in nature, they don’t have any tendency to either accept or donate the electrons but both nitrogen and hydrogen atoms have a tendency to share their valence electron with each other and hence, complete the octet and make a stable NH3 covalent compound.
As we see in the above figure when one nitrogen and 3 hydrogens approach each other, they make a covalent bond in NH3 because of sharing of electrons.
“NH3 is a covalent bond. This is because, Nitrogen and Hydrogen have shared the electron. The main difference between an ionic and covalent bond is ionic bond will donate or accept electron.”
Examples of some compounds that form covalent bonds – are H2O, H2S, SO2, NO2, AlCl3, etc.
The covalent bond is formed in NH3 because one nitrogen and 3 hydrogen atom share the valence electron with each other to get stability.
Let’s see how covalent bond formation takes place in NH3.
There are two types of atoms present in the ammonia molecules – hydrogen and nitrogen atom.
⇒ The hydrogen atom is a nonmetal that belongs to Group I in the periodic table and has only one valence electron in the outermost shell.
⇒ The nitrogen atom is also a nonmetal that belongs to Group 15 in the periodic table and has a 5 valence electron in its outermost shell.
The rule is when two or more atoms come together then they want to complete their octet i.e. having 8 valence electrons in the outermost shell, to attain stability. The octet can be completed either by sharing the valence electrons or completely transferring the valence electron to another atom.
In the case of an NH3 molecule, when nitrogen and hydrogen atom approaches, they completed their octet by sharing the valence electrons with each other and attaining stability.
Note: The hydrogen atom has only one valence electron in its outermost shell and for completing the octet it needs only one more electron.
Hydrogen atom is exception to the octet rule as it need only two valence electron in its outershell to complete the octet.
Therefore, both hydrogen and nitrogen atoms will share the electrons with each other to complete the octet and due to this, a bond is formed between them which is called a covalent bond.
As we see in the above picture of covalent bond formation in NH3, the nitrogen atom has 5 valence electron in its outermost shell and it needs 3 more to complete the octet, hence, 3 hydrogen atom shares one electron each with the nitrogen atom.
In this process, 3 hydrogen atom and one nitrogen atom completed their octet as the nitrogen atom gets 8 electrons in its outer shell and each hydrogen gets 2 electrons in its octet shell.
So, every atom in the NH3 molecule completed its octet by sharing electrons, hence, making a covalent bond.
Therefore, we can say ammonia (NH3) has a three covalent bond(N-H) that contains 6 shared pairs of electrons or bonded pairs of electrons.
Note: NH3 molecule also contains 2 lone pairs of electrons but they never take part in the formation of a covalent bond, only shared electrons are used to make a covalent bond. After all, the covalent bond is made between the two atoms that share the electrons with each other.
Why is NH3 not a ionic compound?
The NH3 molecule is not an ionic compound because the difference in electronegativity value between nitrogen and a hydrogen atom is not big enough to make an ionic bond between them according to the Pauling scale.
According to the Pauling scale of electronegativity-
The covalent bond is formed between the two atoms when their electronegativity difference occurs less than 1.7.
The ionic bond is formed between the two atoms when their electronegativity difference occurs more than 1.7.
Now check the electronegativity difference in the NH3 molecule-
⇒ The electronegativity value for hydrogen atom = 2.2
⇒ The electronegativity value for nitrogen atom = 3.04
∴ The difference in the electronegativity between nitrogen and hydrogen atoms = 0.84
So, the difference in electronegativity in the N-H bond is less than 1.7, hence, it is low enough to make a covalent bond between them as per the Pauling scale of electronegativity.
Also, the main difference between ionic and covalent is that an ionic bond is formed when either donating or accepting the electrons occurs between two atoms, and a covalent bond is formed when only sharing of electrons occurs between two atoms.
The nitrogen and hydrogen atoms in the NH3 molecule can never transfer their electrons because their octet can be completed only when they share the electrons with each other, hence, the bond formed in the NH3 molecule is covalent in nature rather than ionic.
Examples of some ionic compounds – MgO, Na2O, MgCl2, NaCl, etc.
A pure covalent bond is mostly formed in the molecule that has the same type of atoms and the same electronegativity, for example – O2, F2, Cl2, etc.
Basically, a homonuclear molecule has the ability to form a pure covalent bond because the electronegativity of atoms is the same, hence, sharing of electrons is also equal to them.
In short, a pure covalent bond is formed between the atoms when they share an equal number of electrons.
So, Is NH3 a pure covalent compound? No, NH3 is a not pure covalent compound because it is a heteronuclear molecule that contains different types of atoms (nitrogen and hydrogen atom), and their electronegativity is also not the same.
The electronegativity for hydrogen is 2.2 whereas, for nitrogen, it is 3.04. So, the electrons are more shared towards the nitrogen atom as it is higher electronegative than the hydrogen atom, hence, unequal sharing of electrons occurs between nitrogen and hydrogen atoms.
So, the bonds formed in the NH3 molecule are not a pure covalent bonds, hence, NH3 is not a pure covalent compound.
Is NH3 polar covalent or nonpolar covalent compound?
A polar covalent compound is formed when the unequal sharing of electrons occurs between two atoms because of their difference in electronegativity value.
When the difference of electronegativity value between two atoms lies in between 0.4 to 1.7, then the bond formed between two atoms is polar in nature according to the Pauling scale of electronegativity.
A nonpolar covalent compound is formed when the equal sharing of electrons occurs between two atoms because of the very little difference in their electronegativity value.
When the difference in electronegativity value between two atoms is less than 0.4, then the bond formed between two atoms is nonpolar in nature according to the Pauling scale of electronegativity.
So, Is NH3 a polar covalent or nonpolar covalent compound? NH3 is a polar covalent compound because the electronegativity difference between nitrogen and a hydrogen atom is 0.84 which is in the range of the Pauling scale of the polar compound from 0.4 to 1.7.
Also, the unequal sharing of electrons occurs in NH3 molecules because nitrogen(3.04) is higher electronegative than a hydrogen atom(2.2), hence, it will pull more electrons towards itself, hence, the nitrogen atom induced a negative charge on it and hydrogen atoms get a slightly positive charge.
The separation of charges generates the dipole moment directed from positive to negative, hence, due to all these a bond is formed between nitrogen and hydrogen, which is called a polar bond.
Why do atoms in NH3 share the electron with each other to complete the octet and make a covalent bond?
This is because nitrogen and hydrogen are nonmetals in nature, which makes them more prone to sharing the electron with each other, also, the transferring of electrons cannot take place between nitrogen and hydrogen atoms because for competing in the octet they need to share the electrons as both atoms have incomplete octet shell.
Why is NH3 not a pure covalent compound?
The nitrogen atom is more electronegative than hydrogen, hence, it attracts more electrons towards itself. So, the unequal sharing of electrons occurs between nitrogen and hydrogen. This makes an NH3 molecule a non-pure covalent bond.
How covalent bond is formed in NH3 (ammonia)?
The hydrogen atom has one valence electron and the nitrogen atom have 5 valence electrons in its outermost shell, hence, hydrogen needs 1 electron, and nitrogen needs 3 more electrons to complete the octet, so, each hydrogen atom in the NH3 molecule shares the 1 electron with a nitrogen atom.
Hence, both of these atoms get full octet by sharing the electrons with each other. And in this process, a bond is formed between them which is called a covalent bond.
Summary
Is ammonia (NH3) ionic or covalent? NH3 (ammonia) is a covalent compound. Because the bond is formed between one nitrogen and three hydrogen atoms through the sharing of electrons with each other.
There are three N-H covalent bonds present in the NH3 molecule.
Ammonia (NH3) is not a pure covalent compound, since, the electrons are shared more towards nitrogen atoms, hence, unequal sharing occurs in it.
The difference in electronegativity between nitrogen (N) and Hydrogen (H) is 3.04–2.2=0.84 which is lower than 1.7, hence, according to the Pauling scale, the bond formed between nitrogen and a hydrogen atom (N-H) is covalent, which makes, NH3 compound, covalent in nature.
The covalent bond formed in the NH3 molecule is polar in nature, since, the nitrogen is more electronegative than the hydrogen atom hence, it strongly pulls an electron towards itself and this generates the dipole moment which leads to its polar nature.
Vishal Goyal is the founder of Topblogtenz, a comprehensive resource for students seeking guidance and support in their chemistry studies. He holds a degree in B.Tech (Chemical Engineering) and has four years of experience as a chemistry tutor. The team at Topblogtenz includes experts like experienced researchers, professors, and educators, with the goal of making complex subjects like chemistry accessible and understandable for all. A passion for sharing knowledge and a love for chemistry and science drives the team behind the website. Let's connect through LinkedIn: https://www.linkedin.com/in/vishal-goyal-2926a122b/
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