Lewis structure for HClO2
The correct answer and explanation is:
Sure! Here’s the Lewis structure for chlorous acid (HClO₂) and a detailed explanation:
Lewis Structure of HClO₂ (Chlorous Acid)
- Count total valence electrons:
- H (hydrogen): 1 valence electron
- Cl (chlorine): 7 valence electrons
- O (oxygen): 6 valence electrons × 2 = 12 valence electrons
Total valence electrons = 1 + 7 + 12 = 20 electrons
- Determine the central atom:
Chlorine (Cl) is less electronegative than oxygen, so Cl is the central atom. Hydrogen will be bonded to oxygen, as hydrogen typically bonds with oxygen, not chlorine.
- Connect atoms with single bonds initially:
- Cl central atom
- Two oxygens bonded to Cl
- Hydrogen bonded to one oxygen (since H-O bonds are common)
- Distribute remaining electrons to satisfy octets:
- Each single bond uses 2 electrons
- Cl-O bonds = 2 bonds × 2 electrons = 4 electrons
- O-H bond = 1 bond × 2 electrons = 2 electrons
- Total electrons used in bonds = 6 electrons
- Remaining electrons = 20 – 6 = 14 electrons
Assign lone pairs to oxygen atoms first to complete octets.
- Add double bond if necessary:
If both oxygens have full octets and chlorine does not, try a double bond between Cl and one oxygen to satisfy octet rule for Cl.
Final Lewis structure (simplified):
- Cl bonded to one oxygen by a double bond (O=Cl)
- Cl bonded to the other oxygen by a single bond (Cl–O)
- The single-bonded oxygen also bonded to hydrogen (O–H)
- Lone pairs complete octets:
- Double-bonded oxygen has 2 lone pairs
- Single-bonded oxygen has 2 lone pairs
- Chlorine has 1 lone pair
Explanation (about 300 words):
The Lewis structure of chlorous acid (HClO₂) reflects how the atoms share electrons to achieve stable electron configurations, especially octets for second-row elements like oxygen and chlorine. First, we count the total valence electrons from each atom, summing to 20 electrons. Hydrogen contributes one electron, chlorine seven, and each oxygen six, as these elements belong to groups 1, 17, and 16 of the periodic table, respectively.
Chlorine is chosen as the central atom because it is less electronegative than oxygen and can expand its octet due to available d orbitals, unlike oxygen and hydrogen. Hydrogen, being a terminal atom, bonds to oxygen rather than chlorine.
We initially connect the atoms with single bonds: Cl to both oxygens and hydrogen to one oxygen. This uses six electrons. To satisfy the octet rule, we distribute the remaining 14 electrons as lone pairs on the oxygen atoms first, because oxygen strongly prefers to complete its octet. If the central chlorine lacks a full octet, we form a double bond between chlorine and one oxygen atom. This double bond allows chlorine to share more electrons, reaching a stable configuration.
The final structure shows chlorine bonded to one oxygen with a double bond and to the other oxygen with a single bond, which in turn bonds to hydrogen. The double-bonded oxygen holds two lone pairs, and the single-bonded oxygen has two lone pairs as well. Chlorine has one lone pair. This arrangement respects the octet rule for all atoms except chlorine, which can accommodate more than eight electrons due to its third-period position. The structure explains chlorous acid’s reactivity and acid behavior since the O-H bond can dissociate to release H⁺ ions in aqueous solutions.