N2O5 Lewis Structure & Characteristics (13 Complete Facts)

N­₂O₅ or dinitrogen pentaoxide is a strong oxidizer having a molecular weight of 108.01 g/mol. Let us discuss the molecular property of N₂O₅ in detail.

N₂O₅ is an oxide of nitrogen where N has its +5 oxidation state which is maximum in the stable form. The molecule exists as an ion separation form, each N contains positive charge and two O contains negative charge. It is very unstable and reactive due to electronegative atoms present in the molecule.

N₂O₅ is a good reagent for organic chemistry to incorporate the nitro group in any molecule, so it can be used in many organic reactions. Now we will discuss the molecular property along with lewis structure, hybridization, and polarity of N₂O₅ in detail in the following section with proper explanation.

1.      How to draw the N₂O₅ lewis structure?

With the help of the octet rule, valency, and valence electrons we can draw the lewis structure of the N₂O₅ in a few steps. Let us draw the lewis structure of N₂O₅.

Counting the valence electrons

In the first step of drawing lewis’s structure, counting the total valence electrons should be done. Counting valence electrons for a molecule means counting the valence electrons for individual atoms. The total valence electrons for the N₂O₅ are 40 to which N and O contribute their valence electrons.

Choosing the central atom

2^nd step for drawing the lewis structure is select one atom as the central atom among all and other atoms should be connected through a bond with that central atom. N is selected as the central atom here because it has a larger size and less electronegativity than O, both N atoms are central here.

Satisfying the octet

Each atom in the N₂O₅ satisfied to octet by completing the valence shell with electrons. N and O both complete their valence shell by 8 electrons as they belong to the p block. The total electrons needed for octet in N₂O₅ is 7*8 = 56 and those number of electrons are accumulated by sharing bonds.

Satisfying the valency

During the bond formation by satisfying the octet each atom should be satisfied by its stable valency. The electrons needed as per octet are fulfilled by their valency to make bonds. The excess electrons should be accommodated by extra bonds and those bonds must be justified by stable valency of each atom.

Assign the lone pairs

After making the suitable bonds by the atoms if excess electrons are present in the valence orbital, it is assigned as lone pairs over the particular atom. N makes more bonds than its valency so it does not contain any lone pairs but each O atom contains four lone pairs of electrons.

2.      N­₂O₅ valence electrons

Valence electrons for the N₂O₅ are the combination of the valence electrons of N as well as O. Let us count the total number of valence electrons present in N₂O₅.

N₂O₅ has 46 valence electrons where both N and five O contribute their valence electrons individually. The electronic configuration of N and O are [He]2s²2p³ and [He]2s²2p⁴ respectively. So, valence electrons counting each N has 5 and O has 6 electrons and then added them together to get valence electrons.

• The valence electrons that contribute to N are, 5 (confirmed by the electronic configuration)
• The valence electrons that contribute to O are, 6 (confirmed by the electronic configuration)
• The total number of valence electrons for two N and five O for N₂O₅ is, (5*2) + (6*6) = 46.

3.      N₂O₅ lewis structure lone pairs

In the N₂O₅ only the O atom contains lone pairs, but N does not contain any lone pairs here. Let us calculate the lone pairs over the N₂O₅.

N₂O₅ contains 10 pairs of lone pairs and all the lone pairs are present over only five O atoms. Because each O has more electrons than valence electrons than bonding electrons, N makes bonds exceed its valency so it does not have electrons to exist as lone pairs. Add them together to get total of lone pairs.

• The total lone pairs present in the N₂O₅ are to be calculated by the formula, lone pairs = electrons present in the valence orbital – electrons involved in the bond formation.
• The lone pairs present over the N atoms are 5-4 = 1
• The lone pairs present over the O atoms are, 6-2 = 4
• The lone pairs present over the terminal O atoms are, 7-1 = 6
• So, the total lone pairs present over the N­₂O₅ are 4*2 + 6*2 = 20 electrons which mean 10 pairs of lone pairs.
• N has only one electron left, so it has no pair of electrons.

4.      N₂O₅ lewis structure octet rule

In the N₂O₅ molecule, N and O follow the octet during the bond formation by fulfilling their valence shell. Let us know about the octet of N₂O₅.

The electrons required for the octet of N₂O₅ are 56, and the valence electrons are 46 so, the excess 56-46 = 10 electrons should be filled by the 10/2 = 5 bonds, but in the N2O5 there will be 8 bonds present due to satisfied their valency, although N fulfil its octet due valency it gets a positive charge.

The terminal O atoms make only one bond that’s why it gets more electrons in its valence shell and for this reason, it gets a negative charge, but the valency is not satisfied here. O has stable di valency but terminal O atoms make only one bond and gets a negative charge over it to complete octet.

5.      N₂O₅ lewis structure shape

The molecular shape of the N₂O₅ is the orientation of the N and O atoms by the proper arrangement to get a particular shape. Let us predict the shape of N₂O₅.

The molecular shape of the N₂O₅ is trigonal planar around both central N atoms which can be confirmed by the following table,

N₂O₅ is an AX₃ type molecule because it is tri-coordinated and as per VSEPR (Valence Shell Electrons Pair Repulsion) theory, the molecule of AX₃ adopted trigonal planar geometry if there are no lone pairs present over the central atom like N₂O₅.

6.      N₂O₅ lewis structure angle

The angle made by the atoms in particular geometry is the proper arrangement of the atom without steric repulsion. Let us calculate the bond angle of N₂O₅.

The N-O-N bond angle is 112⁰ in the N₂O₅ molecule because it is a trigonal planar molecule and for this type of molecule, the general bond angle is 120⁰. But there is a repulsion between lone pairs and bond pairs for this reason the molecule changes its bond angle to such that repulsion will be minimized.

• The bond angle can be calculated from the hybridization value of the central atom.
• The bond angle formula according to Bent’s rule is COSθ = s/(s-1).
• The central atom N is sp² hybridized, so the s character here is 1/3^rd
• So, the bond angle is, COSθ = {(1/3)} / {(1/3)-1} =-( ½)
• Θ = COS^-1(-1/2) = 120⁰
• But due to steric reasons, the bond angle decreased from its actual value to 112⁰.

7.      N₂O₅ lewis structure formal charge

The presence of charge over any atom in a molecule is determined by the formal charge by assuming equal electronegativity. Let us calculate the formal charge for N­₂O₅.

The formal charge of the N₂O₅ molecule is zero, but the N and terminal O have a charge over them, so there is an equal and opposite charge present that can neutralize the molecule. But separately those atoms are charged or charge is present over those atoms in the N₂O_5. So, their bond will be more polar.

• The formal charge of the N₂O₅ can be calculated by the formula, F.C. = N_v – N_l.p. -1/2 N_b.p
• The formal charge present over each N atom is, 5-0-(8/2) = +1
• The formal charge over each terminal O atom is, 6-6-(2/2) = -1
• The formal charge over double bonded O atom is, 6-4-(4/2) = 0
• So, there are two N containing +1 formal charge and two O containing -1 formal charge, so they can neutralize each other by their formal charge and make the molecule neutral.

8.      N₂O₅ hybridization

Although N and O belong to the same the orbital energy is different and for this reason, they undergo hybridization to make a proper bond. Let us see the hybridization of N₂O₅.

The central N in the N₂O₅ is sp² hybridized and it can be confirmed by the following tale,

• We can calculate the hybridization by the convention formula, H = 0.5(V+M-C+A),
• So, the hybridization of central N is, ½(4+2+0+0) = 3 (sp²)
• One s orbital and two p orbitals of N are involved in the hybridization.
• The double bond between N and O is not involved in the hybridization.

9.      N₂O₅ solubility

To check the solubility of N₂O₅ we have used different type of solvent where they can fully dissociate and gets soluble. Now we see the solubility of N₂O₅.

N₂O₅ is not soluble in water rather it reacts with water to form nitric acid. Because dinitrogen pentoxide is a gaseous molecule and for a gaseous molecule it’s very difficult to soluble in polar water molecules rather can be adsorbed, but here it can react with a water molecule to form an acid molecule.

N₂O₅ can be soluble in other following solvents

• Negligible in CCl₄
• Partial soluble in CHCl₃
• Or any organic solvent

10. Is N₂O₅ solid or liquid?

The physical state of the N₂O₅ depends on the force attraction between the atoms and the temperature applied. Let us see whether N₂O₅ is solid or liquid.

N₂O₅ is a solid molecule, it appears as a white solid because the oxide contains more double bonds, so the van der Waal’s force of attraction is very high here and all the atoms are present nearby. So, it can exist as a solid form at room temperature.

In the solid form, it adopts a hexagonal crystal structure and this kind of crystal is not so strong so, it can melt at normal temperature, that’s why its melting point is very low.

11. Is N₂O₅ polar or nonpolar?

The polarity of the molecule depends on the resultant dipole-moment value and electronegativity difference between atoms. Let us see whether N₂O₅ is polar or not.

N₂O₅ is polar because it has a permanent dipole-moment having value 1.4. This permanent dipole moment creates due to the electronegativity difference between N and O atoms and also it is an asymmetrical molecule so the direction of the dipole moment cannot be opposed to others. So, the molecule is polar.

Due to the electronegativity difference, there is a dipole-moment flow that occurs from electropositive N towards electronegative O atoms. But the direction of the dipole moment is independent of other and create a permanent dipole moment here.

12. Is N₂O₅ acidic or basic?

The acidic or basic nature of oxide is determined when it reacts with water and formed which type of molecule. Let us see whether it is acidic or basic.

N₂O₅ is an acidic oxide because when it reacts with water it formed nitric acid, which is a strong acid. Also, the oxidation state of N is here +5, so it exists at its higher oxidation state and in higher oxidation then it cannot be further oxidized and behaves as acidic. Also, non-metal oxides are acidic.

But according to the Arrhenius theory, it cannot be released H⁺ or OH^– as it lacks both ions, so it neither be acidic nor basic itself.

13. Is N₂O₅ electrolyte?

To check the electrolytic nature of the N₂O₅ we have to see the ionization mechanism of the molecule in an aqueous solution. Let us check if N₂O₅ is an electrolyte or not.

N₂O₅ is not an electrolyte, because when it is dissolved in water it starts to react with it and forms another molecule. So, we cannot predict the ionization mechanism of the N₂O₅ in an aqueous solution. So, we cannot conclude whether that is an electrolyte or not, because it cannot soluble in water.

But the acid it forms nitric acid can be dissociated in the aqueous solution to form charged particles and can carry electricity, so its product by reaction of water can be an electrolyte.

14. Is N₂O₅ ionic or covalent?

A molecule is covalent or ionic to known by its bonding mechanism, whether it is formed by sharing electrons or electron donation. Let us see if it is ionic or covalent.

N₂O₅ is a pure covalent molecule because it forms by the sharing of the electrons between N and O atoms, although there is a partial polar character present in the bond as both are electronegative atoms. But the central N undergoes hybridization to make the proper covalent bond.

According to Fajan’s rule, no molecule is % covalent or ionic, the ionic molecule can be covalent or vice versa, it depends on the theory of polarizability.

Conclusion

Dinitrogen pentaoxide is a very dangerous and unstable oxide. It can react with different types of molecules and in organic chemistry, it can incorporate the nitro group into other functionality. The N is in a + oxidation state so it can be used as a strong oxidizing agent also.

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Biswarup Chandra Dey

Hi……I am Biswarup Chandra Dey, I have completed my Master’s in Chemistry from the Central University of Punjab. My area of specialization is Inorganic Chemistry. Chemistry is not all about reading line by line and memorizing, it is a concept to understand in an easy way and here I am sharing with you the concept about chemistry which I learn because knowledge is worth to share it.