Is Nitrogen dioxide (NO2) ionic or covalent? Types of bond in NO2
Nitrogen dioxide appears as brown gas has an odor like chlorine, made up of one nitrogen and two oxygen atoms having chemical formula NO2. It also appears as a yellowish-brown liquid when cooled or compressed. It is paramagnetic in nature and toxic by inhalation and skin absorption. It is a highly poisonous gas.
In this article, we will discuss Is Nitrogen dioxide (NO2) covalent or ionic? Bond types, etc.
So, Is NO2 covalent or ionic? NO2 is a covalent compound. This is because the bond is formed between one nitrogen and two oxygen atom by the sharing of electrons.
Also, the difference of electronegativity between nitrogen (N) and oxygen (O) atoms on the Pauling scale is not big enough to make an ionic bond in the NO2 compound.
Why Nitrogen dioxide (NO2) is an covalent compound?
A covalent compound is a chemical compound that is made when two nonmetals or two p-block elements together share their valence electrons 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”.
Nitrogen dioxide (NO2) is a covalent compound. Because the nitrogen (N) and oxygen (O) atoms are nonmetals in nature, they don’t have any tendency to either accept or donate the electrons but both nitrogen and oxygen atoms have a tendency to share their valence electron with each other and hence, complete the octet and makes a stable NO2 covalent compound.
As we see in the above figure, the three atoms(two oxygen and one nitrogen) share a total of six electrons with each other through the help of one double bond and one single bond. Hence, the bond formed in the NO2 compound is covalent in nature as shared bonding electrons occur between the nitrogen and oxygen atom.
Examples of some compounds that form covalent bonds – are H2O, H2S, NH3, SO2, AlCl3, etc.
The covalent bond is formed in NO2 because of sharing of electrons occur between nitrogen and oxygen atom.
Let’s see how covalent bond formation takes place in NO2.
First of all, there are two types of atoms present in the nitrogen dioxide molecule – nitrogen and an oxygen atom.
⇒ The nitrogen atom is a nonmetal that belongs to Group 15 or 5A in the periodic table and has five valence electrons in the outermost shell.
⇒ The oxygen atom is also a nonmetal that belongs to Group 16 or 6A in the periodic table and has a 6 valence electron in its outermost shell.
Every atom wants to complete its octet i.e. having 8 electrons in the outermost shell and attaining stability. Atoms can complete their octet by bonding with other elements or atoms with the help of either sharing of electrons or the complete transfer of electrons.
In the case of a NO2 molecule, when nitrogen and oxygen atoms are placed together, they will share the electrons with each other to complete their octet and hence, makes a covalent bond.
Both nitrogen and oxygen atom needs some electrons to complete their octet, hence, both of these(one nitrogen and two oxygen atoms) shares a total of 6 valence electrons with each other.
Nitrogen shares a total of three valence electrons with the two oxygen atoms. one oxygen atom shares two valence electron and another oxygen shares one valence electron with the nitrogen central atom.
The three atoms(one nitrogen and two oxygen atoms) will share a total of six valence electrons, the equivalent of one double bonds and one single bond.
Therefore, the bond formed between nitrogen and oxygen atom is covalent in nature.
Note: The lone pair electrons can never take parts in chemical bonding or they never share electrons with any of the atoms. The shared pair of electrons is also called bonded pair of electrons.
Why is NO2 not a ionic compound?
The NO2 molecule is not an ionic compound because the difference in electronegativity value between nitrogen and an oxygen 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 NO2 molecule-
⇒ The electronegativity value for nitrogen atom = 3.04
⇒ The electronegativity value for oxygen atom = 3.4
∴ The difference in the electronegativity between nitrogen and oxygen atoms = 0.4
So, the difference in electronegativity value between nitrogen and oxygen atom 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 oxygen atoms in the NO2 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 NO2 molecule is covalent in nature rather than ionic.
Examples of some ionic compounds – MgO, Na2O, MgCl2, NaCl, etc.
So, Is NO2 a pure covalent bond? No, it is not. First of all, understand the actual means of a pure covalent bond.
We know, that NO2 is a covalent compound but whether it is pure or not that depends on the sharing of electrons that occur between the atoms(nitrogen and oxygen).
A pure covalent bond is formed when the electronegativity values of the two or more atoms in a molecule are the same. If the electronegativity value is the same for atoms, then the sharing of electrons between them is also equal, hence, the bond forms between them are pure covalent in nature.
In short, a pure covalent bond is formed between the atoms when they share an equal number of electrons.
But NO2 or nitrogen dioxide molecule is not a pure covalent compound because the difference of electronegativity value in nitrogen(3.04) and oxygen(3.4) caused unequal sharing of electrons between them.
The electrons are more shared towards the oxygen atom as it is more electronegative than nitrogen, hence, unequal sharing of electrons occurs in the NO2 compound, which makes it a not pure covalent compound.
Is NO2 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 occurs between two atoms lies 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 occurs 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 NO2 a polar covalent or nonpolar covalent compound? NO2 is a polar covalent compound because the electronegativity difference between nitrogen and an oxygen atom is 0.4 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 NO2 molecules because oxygen(3.4) is higher electronegative than a nitrogen atom(3.04), hence, it will pull more electrons towards itself, hence, the oxygen atom induced a negative charge on it and nitrogen atom 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 oxygen, which is called a polar bond.
Properties of nitrogen dioxide
It has a molar mass of 46.066 g mol−1.
It has an odor similar to chlorine.
It has a boiling point of 21.15 °C and a melting point of −9.3 °C.
It is an extremely poisonous gas.
It is soluble in chloroform, CCl4, and nitric acid.
In the liquid state, it appears as a yellowish-brown colored compound and in the gaseous state, it appears as a reddish-brown gas.
It acts as a pollutant and helps in absorbing UV light.
It is paramagnetic in nature.
Uses of nitrogen dioxide
It is used as an intermediate in the industrial synthesis of nitric acid.
It is used as a flour bleaching agent.
It is used as an oxidizer in rocket fuel.
It is also used as a polymerization inhibitor for acrylates.
FAQ
How many covalent bonds are present in a NO2 molecule?
A covalent bond is formed when sharing of electrons is done between the atoms to achieve the noble gas configuration.
NO2 has one double and one single covalent bond as a nitrogen atom is single bonded to an oxygen atom and double-bonded with another oxygen atom.
Why is NO2 polar covalent compound?
NO2 is a polar covalent compound because the electronegativity difference between nitrogen and an oxygen atom is 0.4 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 NO2 molecules because oxygen(3.4) is higher electronegative than a nitrogen atom(3.04), hence, it will pull more electrons towards itself, hence, the oxygen atom induced a negative charge on it and nitrogen atom 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 oxygen, which is called a polar bond.
Summary
Is Nitrogen dioxide (NO2) ionic or covalent? NO2 is a covalent compound. Because the difference in electronegativity between nitrogen (N) and oxygen (O) is low enough to result in sharing of electrons which leads to the formation of a covalent bond in NO2.
The covalent bond formed in the NO2 molecule is polar in nature.
NO2 is not a pure covalent compound because of the unequal sharing of electrons between atoms.
The difference in electronegativity between Oxygen (O) and Nitrogen (N) is 3.4–3.04=0.4 which is lower than 1.7, hence, according to the Pauling scale, the bond formed between oxygen (O) and a nitrogen (N) atom is covalent, that makes, NO2 compound, covalent in 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/
2 thoughts on “Is NO2 covalent or ionic or both? Types of bond in NO2”
M M sahil
This article carry wrong information.this is an odd electron species. But you mentioned lone pair of electron in fig. And another, If you symbolises the valence electrons of oxygen with orenge dot then one oxyge (which is single bonded in your fig) have 7 valence electrons which is wrong. Please update the article.
Vishal Goyal
Hi, please check the lewis structure of NO2, it will help you to clear your doubt regarding electron places on the figure. https://www.youtube.com/embed/0XTkO8KypUY
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This article carry wrong information.this is an odd electron species. But you mentioned lone pair of electron in fig. And another, If you symbolises the valence electrons of oxygen with orenge dot then one oxyge (which is single bonded in your fig) have 7 valence electrons which is wrong. Please update the article.
Hi, please check the lewis structure of NO2, it will help you to clear your doubt regarding electron places on the figure.
https://www.youtube.com/embed/0XTkO8KypUY