HClO2 Lewis Structure, Characteristics: 25 Complete Quick Facts


This article contains only the HClO2 lewis structure and its 31st important facts in detail. Let’s start the article by drawing the HClO2 lewis structure.

Chlorus acid or HClO2 lewis structure consists of oxoacid of halogen Cl. The central Cl atom is sp3 hybridized in this acid. There is one dπ-pπ bond present between Cl and O. It is less acidic than HClO3 due to a shortage of one O atom. It is a binary compound. The oxidation state of central Cl in the HClO2 lewis structure is +3.

Due to the moderate oxidation state HClO2 can acts as an oxidizing or reducing agent, but it acts as an oxidizing agent in many redox reactions. The molecular geometry is tetrahedral around central Cl, due to the presence of two pairs of lone pairs and three bond pairs and one of them is a π bond.

Some facts about HClO2

The conjugate base of HClO2 is ClO2, which name is chlorite and the suffix is end with “ous” instead of “ite”. Based on the conjugate base, the acid gets its name. based on the stability of the conjugate base the acid is also decided by its acidity and how strong is. The oxidation state of cl is intermediate value in this acid so it is prone to disproportionation reaction and disproportionated to hypochlorous (+1) and chloric acid (+5).

2 HClO2 → HClO + HClO3

 III                    I           IV

The molar mass of HClO2 is 68.46 g/mol. The pka value of chlorous acid is 1.96, so it is less acidic than HClO3.

The method of preparation of HClO2 is, by reaction of barium or lead chlorite with diluted sulfuric acid.

Ba(ClO2)2 + H2SO4 → BaSO4 + 2 HClO2

Pb(ClO2)2 + H2SO4 → PbSO4 + 2 HClO2

Only Cl is a halogen that can form an isolable acid formula like HXO2, neither bromous acid nor iodous acid can ever be isolated.

1.    How to draw the HClO2 lewis structure?

For every covalent molecule, it is very important to draw its lewis structure. So, we try to draw the HClO2 lewis structure by following some protocols. This HClO2 lewis structure helps us to find different covalent characters.

HClO2 lewis structure
HClO2 Lewis Structure

In the process of drawing the HClO2 lewis structure, we should find the valence electrons for an entire molecule. We calculate the valence electrons for individual atoms present in the HClO2 lewis structure separately and added them together. Cl is a group VIIA element so it has seven valence electrons in its valence orbital, O is a VIA element so it has six electrons and H has only one electron.

So total valence electrons for HClO2 lewis structure are, 7+(6*2)+1 =20 electrons.

Now we have to choose the central atom for the HClO2 lewis structure. Cl is larger among all the molecules in the HClO2 lewis structure, so we choose Cl as the central atom for the HClO2 lewis structure. Two O and H are attached to the central atom with a suitable number of bonds.

In the HClO2 lewis structure, all the atoms should follow the octet rule. So according to the octet rule, the electrons required for every atom are 2+(3*8) = 26 electrons. But the valence electrons previously calculated for the HClO2 lewis structure are 20 electrons. So, the shortage of electrons are 26-20 = 6 electrons.

That shortage of six electrons will be accumulated by the 6/2 = 3 bonds. So, in the HClO2 lewis structure, there will be a required minimum of 3 bonds. We added all the atoms with the central atom by the required number of bonds.

Two O atoms are added with Cl by two single bonds and h will be attached to one O via a single bond. Being an acid molecule HClO2 should contain one -OH group, so H atoms are attached to the O site, not the Cl.

After adding a suitable number of single bonds, we added multiple bonds if required. To justify the valency of Cl and O we added one more bond between Cl and O. which is a double-bond character and it is a dπ-pπ back bonding also.

Now add the lone pairs over the respective atoms. Two O contains two pairs of lone pairs each and Cl also contains two pairs of lone pairs that are involved in the hybridization.

2.      HClO2 lewis structure shape

The shape of the HClO2 lewis structure is responsible for the lone pairs over the central Cl atoms and also surrounding two O atoms. Due to the lone pair-bond pairs repulsion, the shape somewhat deviates from the actual tetrahedral shape.

HClO2 Shape

The geometry of the HClO2 lewis structure is tetrahedral along with two lone pairs over the central Cl atom. But the electron geometry of the molecule is angular. Actually, without the lone pairs over the Cl atoms, the shape of the HClO2 lewis structure is bent or angular.

A molecule of type AX2  will be linear in shape according to the VSEPR (Valence Shell Electrons Pair ) theory. But if there are lone pairs present over the central atom then its geometry or shape will be changed and deviated from ideal geometry.

Again, from electron count for outer orbital for surrounding atoms as well as central atom and is equal to 8 then its shape will be tetrahedral. So, if we consider the lone pairs over the central Cl atom in the HClO2 lewis structure then the electron counts are 8 and it adopts tetrahedral geometry along with two pairs of lone pairs.

But without lone pairs, the shape cannot be linear for the HClO2 lewis structure due to electron density repulsion for O and Cl atoms.

3.    HClO2 valence electrons

The total valence electrons for the HClO2 lewis structure are the summation of individual valence electrons for every atom present in the molecule. We individually calculate the valence electrons for every atom and then add them together for the HClO2 lewis structure.

The central atom in the HClO2 lewis structure is Cl which is group 17th element in the periodic table, so it has seven valence electrons in the valence orbital. Those seven electrons are involved in the bond formation or lone pairs, so we count seven electrons for Cl as its valence electrons.

2nd important atom in the HClO2 lewis structure is O, which is group 16th element in the periodic table and it also belongs to group VIA. So, it has six valence electrons. Those six electrons are involved in the bond formation and lone pairs in the HClO2 lewis structure, so we consider six electrons for O as its valence electrons.

The remaining H atom has one valence electron in its orbital.

So, the total valence electrons in the HClO2 lewis structure are, 7+(6*2)+1 = 20 electrons.

4.    HClO2 lewis structure lone pairs

The lone pairs are available for those atoms which have many electrons from the bond pair in the valence shell or orbital. Only O and Cl atoms have lone pairs in the HClO2 lewis structure.

In the HClO2 lewis structure, CL has seven valence electrons in its valence shell, but not all the electrons are involved in the bond formation or donation, so the remaining electrons which are not involved in the bond formation exist as lone pairs.

 Cl used only three electrons for bond formation with two O atoms, two single bonds, and one double bond. So, the rest of the four electrons which are present in the valence shell of Cl in the HClO2 lewis structure exist as two pairs of lone pairs over the Cl atom.

Now come in O atoms, O has six valence electrons as it is a VIA element, and both O makes two bonds in the HClO2 lewis structure. One O atom makes one sigma and one π bond with Cl and the other O makes one single bond with Cl and one sigma bond with the H atom.

So basically, two O atoms used two valence electrons in the bond formation, and the rest of the four electrons which are not involved in the bond formation but in contribute octet exists as two pairs of lone pairs over each O atom in the HClO2 lewis structure.

H has no opportunity like that so it is a lack of lone pair.

5.    HClO2 lewis structure octet rule

All the atoms in the periodic table after bond formation try to complete their octet and try to gain the nearest noble gas configuration for a stable state especially s and p block elements always follow the octet rule and in the HClO2 lewis structure, all the atoms are from s and p block so they have to follow the octet rule.

The electronic configuration of Cl is [Ne]3s23p4, it is a group  17th element. Cl belongs to the halogen family and group VIIA. From the electronic configuration of the central Cl atom, we can say that it has seven valence electrons which are present in 3s and 3p orbitals respectively. According to the octet rule, p block element should fulfill the valence shell by eight electrons, so it needs one more electron to complete its octet.

There are five electrons in the 3p orbital of the Cl atom, and the maximum number of electrons accumulated by the p orbital is six, now it forms two single bonds with two O atoms shared with two electrons. Now it has six electrons in its 3p orbital undergoing hybridization. So, Cl fulfills its octet by forming bonds with O undergoing hybridization.

Now for O, the electronic configuration is, [He]2s22p4. O is group 16th element and VIA element. So, it has six valence electrons, where two electrons are in the 2s orbital and four electrons in the 2p orbital. O is also a p block element, so it should follow the octet rule by completing its 2p orbital by six electrons.

Now O forms two bonds one with Cl and one with H, or a double bond with Cl atoms. In these two bonds, O shares its two electrons and the other two electrons come from Cl or H site. So, after sharing in bond formation, O completes its octet by fulfilling its 2p orbital by six electrons and two electrons are already in the 2s orbital.

H is s block element having one electron in its orbital. For the s block element to complete the octet rule, it needs two electrons in the s orbital because the s orbital can accumulate a maximum of two electrons only as it has one subshell. So, H makes a bond with O to share one of its electrons and the other from the O site to complete its octet.

6.    HClO2 lewis structure formal charge

The oxidation state of Cl in the HClO2 lewis structure is +3 but we cannot predict that the molecule is charged or neutral. So, we have to calculate the formal charge for the molecule by considering the same electronegativity for each and every substituent.

The formula we can use to calculate the formal charge, F.C. = Nv – Nl.p. -1/2 Nb.p.

Where Nv is the number of electrons in the valence shell or outermost orbital, Nl.p is the number of electrons in the lone pair, and Nb.p  is the total number of electrons that are involved in the bond formation only.

In the HClO2 lewis structure, there are three different substituents are present so, we have to calculate the formal charge for an individual atom.

The formal charge of Cl is, 7-4-(6/2) = 0

The formal charge of O is, 6-4-(4/2) = 0

The formal charge of H is, 1-0-(2/2) = 0

So, from the calculation of the formal charge of HClO2 lewis structure, it is evident that the molecule is neutral and no charge appears on it or the charge is neutralized fully.

7.    HClO2 lewis structure angle

Due to lone pair-bond pair repulsion, the bond angle decreases from the expected value in the HClO2 lewis structure. If there is any deviation factor present then the bond angle always deviates for proper orientation of the atoms in the molecule.

HClO2 Bond Angle

The geometry around the central Cl in the HClO2 lewis structure is tetrahedral along with two pairs of lone pairs. So, the expected bond angle should be 109.50 according to the VSEPR theory. But here if the O-Cl-O bond angle adopts to 1090 then there should be massive repulsion between the double bond and lone pairs.

We Know lone pairs and double bonds required more space.  So, the molecule will no longer exist in its stable form. So, avoiding such type of repulsion, the O-Cl-O bond angle decreases from its original value and it should nearby 1040. Actually, it adopts a bent type shape, so the bond angle decreases for proper orientation of bond pairs as well as lone pairs.

Again, another bond angle Cl-O-H is also observed in the HClO2 lewis structure. This bond angle is nearly 1040 because the structure is like a water molecule v-shaped. Actually, the geometry around the O is tetrahedral with two lone pairs, but here repulsion is less than in the previous case because her Cl-O single bond is present and the bond distance of a single bond is always greater than a double bond.

So, here repulsion of lone pairs is less and the bond angle is nearly 1040 like a water molecule, as it adopts the same shape as water.

8.    HClO2 lewis structure resonance

The conjugate base of the HClO2 lewis structure is more resonance stabilized than the acid molecule. In the Chlorus ion (ClO2) due to the negative charge, the electron clouds can be delocalized between different skeleton forms via resonance.

HClO2 Resonating Structures

All three structures are different resonating forms of the conjugate base of the HClO2 lewis structure. Among three structures III is the more contributing structure of resonance as it is more stable due to more covalent bonds and the negative charge is present over electronegative atom Cl.

After that structure, II comes, as it contains a lesser number of covalent bonds than structure I but more number than structure I. The structure I is less contributing or less stable as it contains a lesser number of covalent bonds and a positive charge over the electronegative Cl atom which is a destabilization factor.

The overall stability of the conjugate base of the HClO2 lewis structure is III>II>I.

9.    HClO2 hybridization

The energy of orbital of Cl and O are different and it is not easy to form a covalent bond, so they undergo hybridization by mixing orbital to produce a hybrid orbital of equivalent orbital and form a stable covalent bond. The central Cl is sp3 hybridized here.

We used the formula to predict the hybridization of the HClO2 lewis structure is,

H = 0.5(V+M-C+A), where H= hybridization value, V is the number of valence electrons in the central atom, M = monovalent atoms surrounded, C=no. of cation, A=no. of the anion.

In the HClO2 lewis structure, the central Cl atom is, ½(6+2) = 4 (sp3)

Structure    Hybridization value  State of hybridization of central atom    Bond angle
Linear           2          sp /sd / pd            1800
Planner trigonal    3sp2                 1200
Tetrahedral      4sd3/ sp3            109.50
Trigonal bipyramidal 5sp3d/dsp3          900 (axial), 1200(equatorial)
Octahedral            6sp3d2/ d2sp3          900
Pentagonal bipyramidal  7sp3d3/d3sp3            900,720

           

From the hybridization table we can say that if the hybridization value for any central atom is 4 then it should be sp3 hybridized.

Let us under the hybridization of central Cl in the HClO2 lewis structure.

HClO2 Hybridization

From the box diagram of the HClO2 lewis structure, we can say that two pairs of lone pairs over Cl also present a hybrid orbital and we cannot consider the π bond in the hybridization. One s and three p orbitals are involved here.

10. HClO2 solubility

HClO2 soluble in,

  • Water
  • Benzene
  • Carbon tetrachloride

11. Is HClO2 soluble in water?

HClO2 is partial ionic and polar, so it is soluble in water.

12. Is HClO2 an electrolyte?

Yes, HClO2 is an electrolyte in an aqueous solution.

13. Is HClO2 a strong electrolyte?

Yes, electrolysis produces strong H+ ions, so it is a strong electrolyte.

14. Is HClO2 acidic or basic?

Due to the presence of acidic proton HClO2 is acidic.

15. Is HClO2 a strong acid?

HClO2 is a strong acid due to the presence of strong electronegative Cl and O atoms.

16. Is HClO2 polyprotic acid?

No, HClO2 is a monoprotic acid.

17. Is HClO2 a lewis acid?

No, there is no vacant site is present in HClO2.

18. Is HClO2 an Arrhenius acid?

HClO2 releases H+ ion in an aqueous medium, so it is an Arrhenius acid.

19. Is HClO2 polar or nonpolar?

Yes, HClO2 is a polar molecule due to its asymmetric structure and having a resultant dipole moment.

20. Is HClO2 linear?

No, HClO2 is bent-shaped.

21. Is HClO2 paramagnetic or diamagnetic?

Due to the absence of any unpaired electrons, HClO2 is diamagnetic.

22. HClO2 boiling point

The boiling point of HClO2 is high due to the breaking of a double bond.

23. Is HClO2 ionic or covalent?

HClO2 is a covalent molecule.

24. Is HClO2 hydrogen bonding?

No, in the HClO2 there is no H bonding present.

25. Is HClO2 binary or oxoacid

Yes, HClO2 is a binary oxoacid of halogen.

Conclusion

HClO2 is a strong acid as its conjugate base is more stable. The acid is less strong than HClO3, due to the lesser number of O atoms.

Biswarup Chandra Dey

Hi......I am Biswarup Chandra Dey, I have completed my Master's in Chemistry. 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.

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