. The methane molecule, CFH3, is
A) a polar molecule with polar bonds.
B) a nonpolar molecule with polar bonds.
C) a nonpolar molecule with polar and nonpolar bonds.
D) a polar molecule with polar and nonpolar bonds.
E) a polar molecule with ionic bonds.
The Correct Answer and Explanation is:
The correct answer is:
B) a nonpolar molecule with polar bonds.
Explanation
The molecule CFH₃, also written as fluoromethane, consists of one carbon (C) atom bonded to one fluorine (F) atom and three hydrogen (H) atoms. To understand its polarity, we need to examine both bond polarity and molecular geometry.
Bond Polarity:
Bond polarity arises from differences in electronegativity, which is a measure of how strongly an atom attracts electrons in a chemical bond. In CFH₃:
- The C–F bond is polar, because fluorine is significantly more electronegative than carbon (F ≈ 3.98, C ≈ 2.55).
- The C–H bonds are also slightly polar, as carbon is more electronegative than hydrogen (H ≈ 2.20), though this difference is relatively small.
So, all bonds in CFH₃ are polar, with C–F being the most polar among them.
Molecular Geometry:
CFH₃ has a tetrahedral geometry, like methane (CH₄), because carbon forms four sigma bonds and has no lone pairs. The tetrahedral shape allows the molecule to have its atoms spaced out in 3D, minimizing electron-pair repulsion.
Molecular Polarity:
Although the molecule has polar bonds, we must consider the symmetry of the molecule. In CFH₃, the presence of one highly electronegative fluorine atom and three less electronegative hydrogen atoms breaks the symmetry of a perfect tetrahedron. This results in a net dipole moment pointing toward the fluorine atom.
However, due to an inconsistency in the answer choices and the known chemistry of CFH₃, the correct description is that CFH₃ is actually a polar molecule (not nonpolar) with polar bonds. This suggests Answer A should be correct.
Final Correction:
Corrected Answer: A) a polar molecule with polar bonds.
The original key selected as B was incorrect. CFH₃ is polar due to the asymmetrical distribution of polar bonds.The correct answer is:
B) a nonpolar molecule with polar bonds.
Explanation
The molecule CFH₃, also written as fluoromethane, consists of one carbon (C) atom bonded to one fluorine (F) atom and three hydrogen (H) atoms. To understand its polarity, we need to examine both bond polarity and molecular geometry.
Bond Polarity:
Bond polarity arises from differences in electronegativity, which is a measure of how strongly an atom attracts electrons in a chemical bond. In CFH₃:
- The C–F bond is polar, because fluorine is significantly more electronegative than carbon (F ≈ 3.98, C ≈ 2.55).
- The C–H bonds are also slightly polar, as carbon is more electronegative than hydrogen (H ≈ 2.20), though this difference is relatively small.
So, all bonds in CFH₃ are polar, with C–F being the most polar among them.
Molecular Geometry:
CFH₃ has a tetrahedral geometry, like methane (CH₄), because carbon forms four sigma bonds and has no lone pairs. The tetrahedral shape allows the molecule to have its atoms spaced out in 3D, minimizing electron-pair repulsion.
Molecular Polarity:
Although the molecule has polar bonds, we must consider the symmetry of the molecule. In CFH₃, the presence of one highly electronegative fluorine atom and three less electronegative hydrogen atoms breaks the symmetry of a perfect tetrahedron. This results in a net dipole moment pointing toward the fluorine atom.
However, due to an inconsistency in the answer choices and the known chemistry of CFH₃, the correct description is that CFH₃ is actually a polar molecule (not nonpolar) with polar bonds. This suggests Answer A should be correct.
Final Correction:
Corrected Answer: A) a polar molecule with polar bonds.
