Draw the Line Bond Structure for Acetone

Draw the Line Bond Structure for Acetone (C3Hâ‚‚O) Step 2: Step 1A: (ADD HYDROGENS UNTIL EACH CARBON HAS 4 BONDS = OCTET) Use the skeleton structure from step 1A to find: O || C C C Step 1B: Count the total number of valence electrons from all the atoms in the molecule. Chemical formula of molecule Atom # of atoms X X X # of valence electrons = = Total # of electrons in structure = totals Step 3: Subtract the number of electrons used to make the skeleton structure from the total number of valence electrons. Total # of electrons in structure (from step 1 above) # of electrons used in skeleton (from step 2 above) Remaining # electrons to be added= Step 5: Check for Octets Check the structure in step 4 for octets (4 pairs) of electrons around each atom. If octet rule is satisfied, you are done. If octet rule is not satisfied, go to Step 6. # of electrons used in skeleton = (multiply # of bonds in skeleton by 2) Step 4: Add the remaining electrons (if any remain) to the skeletal structure above as lone pairs as evenly as possible on all atoms except hydrogen. Step 6: Use existing lone pairs to make double or triple bonds until the octet rule is satisfied for all atoms

The Correct Answer and Explanation is :

Acetone (C₃H₆O), also known as propan-2-one, is the simplest ketone with a central carbonyl group (C=O) flanked by two methyl groups (CH₃). To draw its Lewis structure, follow these steps:

Step 1A: Skeleton Structure

Arrange the atoms to reflect the molecular formula:

   H3C—C—C—H3
        ||
        O

Here, the central carbon (C₂) is double-bonded to oxygen (O) and single-bonded to two other carbons (C₁ and C₃), each bonded to three hydrogens.

Step 1B: Count Valence Electrons

• Carbon (C): Each carbon atom has 4 valence electrons. With three carbons, that’s 4 × 3 = 12 electrons.
• Hydrogen (H): Each hydrogen atom has 1 valence electron. With six hydrogens, that’s 1 × 6 = 6 electrons.
• Oxygen (O): Oxygen has 6 valence electrons.

Total valence electrons: 12 (C) + 6 (H) + 6 (O) = 24 electrons.

Step 2: Add Hydrogens to Satisfy Carbon’s Octet

Each carbon atom needs four bonds to satisfy the octet rule:

• C₁ and C₃: Each is bonded to three hydrogens, fulfilling their valency.
• C₂ (central carbon): Forms a double bond with oxygen and single bonds with C₁ and C₃, totaling four bonds.

Step 3: Subtract Electrons Used in Skeleton from Total Valence Electrons

• Bonds in skeleton:
• C₁—C₂: 1 bond
• C₂—C₃: 1 bond
• C₂=O: 1 bond
• C₁—H₃, C₃—H₃: 3 bonds each
• Total bonds: 1 + 1 + 1 + 3 + 3 = 9 bonds
• Electrons used: 9 bonds × 2 electrons/bond = 18 electrons

Remaining electrons: 24 total electrons – 18 used electrons = 6 electrons.

Step 4: Add Remaining Electrons as Lone Pairs

Distribute the remaining 6 electrons as lone pairs:

• Oxygen (O): Needs two lone pairs to complete its octet.
• C₂ (central carbon): No lone pairs; all valence electrons are used in bonding.
• C₁ and C₃: No lone pairs; all valence electrons are used in bonding.

Step 5: Check for Octets

• C₁ and C₃: Each has four bonds (three single bonds with hydrogens and one single bond with C₂), satisfying the octet rule.
• C₂: Four bonds (one double bond with O and two single bonds with C₁ and C₃), satisfying the octet rule.
• O: Two lone pairs and one double bond with C₂, satisfying the octet rule.

All atoms have complete octets, confirming the structure is correct.

For a visual demonstration, you can refer to the following video:

Acetone Lewis Structure: How to Draw the Lewis Structure for Acetone