What is the strongest intermolecular force that would act between CH4 molecules? Dipole-dipole interactions, hydrogen bonding, London dispersion forces Draw the Lewis structure of CHF2; Select Draw More Erase 3 Rings
The Correct Answer and Explanation is:
The strongest intermolecular force acting between CH₄ (methane) molecules is London dispersion forces.
CH₄ is a nonpolar molecule. Carbon and hydrogen have a small electronegativity difference, and the tetrahedral symmetry of CH₄ ensures that any dipole moments cancel out, resulting in no permanent dipole. Because CH₄ is nonpolar and has no hydrogen atoms bonded to highly electronegative atoms like nitrogen, oxygen, or fluorine, neither dipole-dipole interactions nor hydrogen bonding applies. That leaves only London dispersion forces, also known as instantaneous dipole-induced dipole interactions. These arise from momentary shifts in electron distribution that induce weak attractions between adjacent molecules. Although relatively weak, London forces are universally present in all molecules, including nonpolar ones like CH₄.
Lewis Structure of CHF₂ (difluoromethane)
- Count valence electrons:
- Carbon: 4
- Hydrogen: 1
- Fluorine (×2): 7 × 2 = 14
- Total = 4 + 1 + 14 = 19 electrons (but that’s odd—so actually the correct molecular formula is likely CH₂F₂, which matches a stable even count of 20 valence electrons)
So assuming the intent was CH₂F₂:
- Determine central atom: Carbon will be at the center.
- Attach outer atoms:
- Carbon forms single bonds with two hydrogen atoms and two fluorine atoms.
- Distribute remaining electrons:
- Each fluorine gets three lone pairs to complete its octet.
- Hydrogen atoms need no lone pairs.
- Structure:
H
|
F – C – H
|
F
This tetrahedral geometry minimizes electron repulsion, obeys the octet rule, and reflects correct valence electron distribution. The polar C–F bonds introduce a molecular dipole, making CH₂F₂ a polar molecule, but CH₄ remains nonpolar. Understanding these distinctions helps predict boiling points, solubility, and behavior in polar versus nonpolar solvents. Want to explore how this molecular polarity affects real-world applications like refrigerants or solvents? I’d be happy to dive in.
