Draw the best Lewis structure for CH2F2. Which of the following is/are true? Select all that apply.
CHF2 is nonpolar
There are dispersion forces between two CH2F2 molecules
There are dipole-dipole forces between two CH2F2 molecules
There is hydrogen bonding between two CH2F2 molecules
The correct answer and explanation is :
To answer the question, we must first understand the structure and intermolecular forces of CH₂F₂ (difluoromethane).
Correct Lewis Structure of CH₂F₂:
The central atom is carbon (C), which forms four single bonds:
- Two bonds to hydrogen atoms (H)
- Two bonds to fluorine atoms (F)
Each fluorine atom also has three lone pairs of electrons. The structure looks like this:
F
|
H — C — H
|
F
(Note: This is a simplified 2D sketch. In 3D, the molecule has a tetrahedral geometry.)
Which of the following are true?
- CHF₂ is nonpolar
❌ False – CH₂F₂ is polar because fluorine is highly electronegative. The dipoles from the C–F bonds do not cancel out due to the tetrahedral geometry, resulting in a net dipole moment. So, CH₂F₂ is polar, not nonpolar. - There are dispersion forces between two CH₂F₂ molecules
✅ True – Dispersion forces (London dispersion) exist between all molecules, polar or nonpolar, due to temporary shifts in electron density. - There are dipole-dipole forces between two CH₂F₂ molecules
✅ True – Since CH₂F₂ is polar, it exhibits dipole-dipole forces between its molecules. - There is hydrogen bonding between two CH₂F₂ molecules
❌ False – While hydrogen is bonded to fluorine, the hydrogen is not directly bonded to F on another molecule. For hydrogen bonding, the hydrogen must be covalently bonded to N, O, or F, and interact with a lone pair on N, O, or F of another molecule. In CH₂F₂, this setup is not met.
Final Answer:
✅ There are dispersion forces between two CH₂F₂ molecules
✅ There are dipole-dipole forces between two CH₂F₂ molecules
❌ CH₂F₂ is not nonpolar
❌ CH₂F₂ does not exhibit hydrogen bonding