Question

select the lewis structure that most accurately represents difluoromethane (cf₂h₂). refer to a periodic table. four lewis structure options are shown in the image, with fluorine, hydrogen, and carbon atoms and their bonding/non - bonding electrons as per the image content

Explanation:

Step1: Determine valence electrons

Carbon (C) has 4 valence electrons, Hydrogen (H) has 1 each (2 H atoms: \(2\times1 = 2\)), Fluorine (F) has 7 each (2 F atoms: \(2\times7 = 14\)). Total valence electrons: \(4 + 2 + 14 = 20\).

Step2: Analyze bonding and lone pairs

• Carbon is the central atom. It forms single bonds with 2 H and 2 F (4 bonds, 8 electrons used in bonding).
• Each F needs 3 lone pairs (6 electrons per F, 2 F: \(2\times6 = 12\) electrons). H has no lone pairs (since H only needs 2 electrons, satisfied by the single bond).
• Total electrons used: \(8 + 12 = 20\), which matches the total valence electrons.
• In the first structure: C is bonded to 2 H (single bonds, no extra dots on H) and 2 F (with 3 lone pairs each). H atoms have no lone pairs (correct, as H's valence is satisfied by the bond). F atoms have 3 lone pairs (correct, as F needs 8 electrons: 2 in bond, 6 in lone pairs).
• The second structure has dots on H, which is incorrect (H can't have lone pairs as it only needs 2 electrons from the bond). The third and fourth have incorrect central atoms (F or C in wrong position), so they are invalid.

Answer:

The first Lewis structure (with H - C - H, F above and below C, each F with 3 lone pairs, no dots on H)