Hypochlorous Acid Lewis Structure

HOCl’s Lewis structure is H–O–Cl with oxygen in the center, two lone pairs on O, three on Cl, and a bent shape (~102.45°).

March 01, 2026

5 min read

Hypochlorous acid (HOCl) is drawn as H–O–Cl, with oxygen as the central atom, single bonds to H and Cl, two lone pairs on oxygen, and three lone pairs on chlorine. This matches the known identity/formula of hypochlorous acid (ClHO / HOCl).

Step-by-step Lewis structure (sciency, but simple)

Count valence electrons

H = 1, O = 6, Cl = 7 → 14 total valence electrons (7 pairs).

Choose the skeleton

Hydrogen almost never sits in the middle (it forms 1 bond), so oxygen goes central: H–O–Cl.
Make single bonds

Two single bonds (H–O and O–Cl) use 4 electrons (2 pairs). Remaining: 10 electrons.
Fill octets with lone pairs

Put 3 lone pairs on Cl (6 e⁻) to complete Cl’s octet.
Put 2 lone pairs on O (4 e⁻) to complete O’s octet.

Now all 14 valence electrons are used.

Check formal charges (they come out clean)

O: 6 − (4 nonbonding + 2 from bonding) = 0
Cl: 7 − (6 nonbonding + 1 from bonding) = 0
H: 1 − (0 nonbonding + 1 from bonding) = 0

So the most reasonable Lewis structure has no formal charges.

Shape + bond angle (why it’s bent)

Around oxygen there are 4 electron regions (2 bonds + 2 lone pairs) → VSEPR predicts a tetrahedral electron arrangement and a bent molecular shape (AX₂E₂) (same idea as water).

Experimentally, the H–O–Cl bond angle is ~102.45° (gas-phase equilibrium geometry, reported in NIST’s CCCBDB experimental geometry listings).

Polarity (why HOCl has a “direction”)

Because the molecule is bent and the atoms differ in electronegativity, the bond dipoles don’t cancel → HOCl is polar. That polarity helps explain why HOCl behaves differently from its conjugate base hypochlorite (OCl⁻) in water.

Acid–base pair: HOCl ⇌ H⁺ + OCl⁻

In water, hypochlorous acid partially dissociates into H⁺ and OCl⁻.

A commonly reported pKₐ is ~7.5–7.6, meaning near neutral pH you can have significant amounts of both HOCl and OCl⁻.

FAQ

Is there resonance in HOCl?

Not in the usual “multiple equivalent Lewis structures” sense. The simplest, best Lewis structure is single-bond H–O–Cl with lone pairs completing octets.

Why is oxygen the central atom, not chlorine?

Hydrogen can only form one bond, so it must be terminal. Oxygen comfortably forms two single bonds here, making it the natural center.

What’s the quickest way to remember HOCl’s shape?

Treat it like water: central O with two bonds + two lone pairs → bent.

Disclaimer

This is general chemistry education, not medical or product-use advice.

References

Andrés, M. T., Fierro, J. F., & Mendoza, E. (2022). Hypochlorous acid: An ideal wound care agent with powerful microbicidal, antibiofilm, and wound healing properties. Journal of Wound Care, 31(Suppl 10), S1–S12. https://pmc.ncbi.nlm.nih.gov/articles/PMC9504810/
Chemistry LibreTexts. (n.d.). The VSEPR model. Chemistry LibreTexts. Retrieved March 1, 2026, from https://chem.libretexts.org/Bookshelves/General_Chemistry/Map%3A_Chemistry_-*The_Central_Science*(Brown_et_al.)/09%3A_Molecular_Geometry_and_Bonding_Theories/9.02%3A_The_VSEPR_Model
National Institute of Standards and Technology. (n.d.). CCCBDB: Experimental bond angles for HOCl (hypochlorous acid). Retrieved March 1, 2026, from https://cccbdb.nist.gov/expangle1ax.asp?descript=aHOCl
National Institute of Standards and Technology. (n.d.). NIST Chemistry WebBook: Hypochlorous acid (CAS 7790-92-3). Retrieved March 1, 2026, from https://webbook.nist.gov/cgi/cbook.cgi?ID=C7790923&Mask=10
National Center for Biotechnology Information. (n.d.). Hypochlorite. In PubChem Compound Summary. Retrieved March 1, 2026, from https://pubchem.ncbi.nlm.nih.gov/compound/Hypochlorite
National Center for Biotechnology Information. (n.d.). Hypochlorous acid. In PubChem Compound Summary. Retrieved March 1, 2026, from https://pubchem.ncbi.nlm.nih.gov/compound/Hypochlorous-Acid
Wikipedia contributors. (n.d.). Hypochlorous acid. In Wikipedia. Retrieved March 1, 2026, from https://en.wikipedia.org/wiki/Hypochlorous_acid

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