HIO3 Lewis Structure, Characteristics: 19 Facts You Should Know

In this article, “hio3 lewis structure” different facts like lewis structure, formal charge calculation, solubility, acidity etc are discussed briefly.

HIO3, known as iodic acid is a white and water soluble compound having molecular weight 175.91 g/mol. It is one of the most stable oxo-acids between all the halogens. Iodine is in +5 oxidation state in HIO3. Iodic acid is used in synthesis of sodium potassium iodate for increasing iodine content of salt.

Let’s focus on the following discussion of HIO3.

How to draw HIO3 lewis structure?

Lewis structure also known as lewis electron dot structure shows the bonding between atoms as well as the lone pairs or nonbonding electrons in the molecule.

  1. Determining the valence electrons: Hydrogen, iodine, oxygen have one, seven and six electrons in their respective valence shell.
  2. Finding out the bonding electrons:  Iodine is attached with two oxygen atoms by two double bonds and with one hydroxyl group by a single bond. Therefore, five valence electrons of iodine and two electrons of each of the oxygen are involved in bond formation.
  3. Determining the nonbonding electrons:  Two valence electrons of iodine and four valence electrons of each of the oxygen are not participating in bond formation. They remain as nonbonding electron pairs.
hio3 lewis structure
HIO3 Lewis Structure

HIO3 Lewis Structure Shape

Hybridization of the central atom is the main term to determine the molecular shape or geometry in absence of any repulsion involving bond pairs and lone pairs. These repulsive factors have great effect on the molecular shape.

For the above repulsion, HIO3 is deviated from its geometrical structure. In HIO3, total two double bonds and one single bond is present between iodine and oxygen atom. Iodine is sp3 hybridized in HIO3 molecule. The geometry of any sp3 hybridized atom should be tetrahedral but due to presence of lone pair, the actual structure of HIO3 is trigonal pyramidal.

HIO3 shape jpeg
Shape of HIO3.
Image Credit: Snappy goat.

HIO3 Lewis Structure Formal Charge

Formal charge is the charge of any atom that resided on that atom if all of the bonding electrons are shared equally. One formula is introduced to calculate the formal charge.

  • Formal charge = Total number of valance electrons – number of electrons remain as nonbonded – (number of electrons involved in bond formation/2)
  • Formal charge of iodine = 7 – 2 – (10/2) = 0
  • Formal charge of each of the oxygen atom = 6 – 4 – (4/2) = 0
  • Formal charge of hydrogen atom = 1 – 0 – (2/2) = 0

HIO3 Lewis Structure Angle

Lewis structure angle denotes the bond angle, which depends upon the hybridization central atom. In HIO3, central atom iodine is sp3 hybridized. The ideal geometry of a sp3 hybridized atom is tetrahedral.

Iodine has two valence electrons left as nonbonding electron pairs. Actual geometry of HIO3 is tetrahedral according to its hybridization. But the fourth vertex of tetrahedron is replaced by a lone pair instead of any atom. Thus, the shape of the molecule becomes trigonal pyramidal and the bond angle will be 1200.

Read more about H2CO lewis structure

HIO3 Lewis Structure Octet Rule

Octet rule states that any atom should attain the electron configuration which should resemble with the electron configuration of its nearest noble gas according to periodic table.

Octet rule is violated in HIO3 because iodine already has seven electrons in its outer most shell. After forming bond with three oxygen atoms (two oxygen atom and one hydroxyl group) iodine gains five more electrons in its valence shell. But the nearest noble gas of iodine is Xenon having electron configuration 5s2 5p6. Thus, the number of valence shell electrons do not match with the Xenon valence shell electrons.

Octet rule is satisfied in oxygen atoms. Oxygen has already six outer most shell electrons and after forming two bonds, it shares eight electrons and matches with its nearest noble gas (Neon) electron configuration (2s2 2p6).

Hydrogen does not obey octet rule, rather it obeys duplet. It has one electron and after bond formation, it gains another electron in its valence shell, which matches with the electron configuration of Helium (1s2).

HIO3 Lewis Structure Lone Pairs

Lone pairs generally do not participate in bond forming with other atoms. They have a significant role in structure determination of any molecule because they are involved in different repulsion which effects the structure.

  • Nonbonded electron = Total number of valance electron – number of bonded electrons.
  • Nonbonding electron of each of the oxygen atom = 6 – 2 = 4 or 2 lone pairs.
  • Nonbonding electron of iodine = 7 – 5 = 2 or 1 pair of lone electrons.
  • Nonbonding electron of hydrogen = 1 – 1 = 0

HIO3 Valence Electrons

Any atom is surrounded by electrons in their respective shell. Among them Valence electrons are the outer most shell electrons which are most loosely bound to the nucleus (due to larger distance from nucleus) and most reactive with comparing to the inner shell electrons because inner shell electrons are tightly bound with the nucleus due to attraction force.

Iodine has seven electrons in its 5s and 5p electrons (5s2 5p5). Each of the oxygen has six electrons in its 2s and 2p orbitals (2s2 2p4). Hydrogen has one electron (1s1) and it is its only valence electrons.

Therefore, total valence electrons in HIO3 = [1+7+ (3×6)] = 26.

HIO3 Solubility

 HIO3 is a white, water-soluble compound. It dissolves in water. The solubility of HIO3 in water is 269 g/100 ml, which indicates that it is highly soluble in water. Its aqueous solution is acidic in nature.

Is HIO3 a strong acid?

Yes, HIO3 is a strong acid. Iodine in HIO3 is an electronegative atom. Thus, the O-H bond becomes polar and hydrogen ion can be eliminated easily from HIO3. After  elimination of H+ ion the conjugate base IO3formed is getting stabilization through conjugation.

Therefore, hydrogen ion can be eliminated easily from HIO3. From the above explanation, it is concluded that HIO3 is a strong acid.

Is HIO3 an oxidising agent?

Yes, HIO3 is a strong oxidizing agent. It can oxidize HI to form molecular iodine. This oxidizing agent is used in the iodination reaction of alkane to destroy the by product HI.

CH3CH3 + I CH3CH3I + HI (in presence of light).

Hi is a very strong reducing agent which converts alkyl iodide to alkane again and the desired reaction is hampered. Thus, HIO3 is used to oxidize HI into molecular iodine (I2) to remove from the reaction medium.

Is HIO3 ionic or molecular?

HIO3 is an ionic compound. Iodine is in +5 oxidation state in HIO3. It can be dissociated into two opposite ions H+ and IO3.

HIO3= H+ + IO3.

Is HIO3 stronger than HBrO3?

No, HBrO3 is stronger acid than HIO3. The reason behind this the larger electronegativity of Br than I. Br attracts the Br-O bonded electron pair towards itself than the iodine. For the greater shift of bonded electron pairs towards the central atom, the O-H bond becomes more polar in HBrO3 than HIO3.

Thus H+ ion can be eliminated easily from HBrO3 with respect to HIO3. As acidity depends upon the elimination of H+ , HBrO3 shows stronger acidity than HIO3.

Is HIO3 binary or oxyacid?

Binary acids are those in which hydrogen is combined with a second non-metallic atom like HCl, HI, HBr etc and oxyacid is defined as the acid in which oxygen atom is present and at least one hydrogen atom is attached with oxygen that can dissociate into H+ cation and an anion containing oxygen.

From the above definition, it is clear that HIO3 is an oxyacid (iodine oxyacid), because it contains oxygen and it can be dissociated into H+ and IO3. It is known as iodic acid.

Is HIO3 amphoteric?

Amphoteric are defined as those compounds which can act as acid as well as base. HIO3 is not an amphoteric compound. It is a strong acid.

Is HIO3 or HIO2 a stronger acid?

HIO3 is stronger acid than HIO2 because HIO3 contains more number of oxygen than HIO2. After H+ elimination, the conjugate acid formed are stabilized by the resonance effect. In HIO3, IO3conjugate base is formed and IO2 is formed for HIO2. The conjugate base of HIO3 is stabilized in a greater extent than the conjugate base of HIO3 due to delocalization of electron density over more atoms in HIO3 (three oxygen atoms and one iodine atom) with respect to HIO2 (two oxygen and one iodine atom).

Conclusion

From the above article on HIO3, it can be concluded that HIO3 is an ionic acid with sp3 hybridization and trigonal planar structure. It is a strong oxidizing agent and used in the salt industry for the synthesis of sodium potassium iodate which is a very important reagent for analytical chemistry.

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