In molecular geometry and polarity, which description best explains the type of molecule CF4 (carbon tetrafluoride) is in terms of overall charge distribution?

Introduction / Context:
Carbon tetrafluoride, CF4, is a classic example used in chemistry to test understanding of molecular shape and polarity. Even though each C F bond is polar due to the electronegativity difference between carbon and fluorine, the overall molecule can still be nonpolar depending on its shape. This question checks whether you can correctly relate the tetrahedral geometry of CF4 to its overall charge distribution and classify it as polar or nonpolar.

Given Data / Assumptions:
- The molecule under discussion is CF4, carbon tetrafluoride. - The central atom is carbon, bonded to four fluorine atoms. - The C F bonds are individually polar because fluorine is more electronegative than carbon. - We assume ideal tetrahedral geometry with identical bond lengths and bond angles.

Concept / Approach:
Molecular polarity depends on both bond polarity and molecular geometry. A polar bond arises when two atoms have different electronegativities, causing an uneven sharing of electrons. However, if these polar bonds are arranged symmetrically in three dimensional space, the individual bond dipoles can cancel out, producing a nonpolar molecule overall. CF4 has a tetrahedral shape with four identical C F bonds directed to the corners of a regular tetrahedron. The symmetry of this arrangement causes the dipoles to cancel, leaving no net dipole moment. Therefore, CF4 is classified as a nonpolar molecule with a symmetrical distribution of charge.

Step-by-Step Solution:
Step 1: Identify the shape of CF4. Carbon in CF4 is surrounded by four bonding pairs and no lone pairs, giving a tetrahedral geometry. Step 2: Recognise that each C F bond is polar because fluorine is significantly more electronegative than carbon. Step 3: Visualise the molecule in three dimensions: the four polar bonds are evenly spaced, pointing toward the vertices of a tetrahedron. Step 4: Consider the bond dipoles. Because of the symmetrical arrangement, each bond dipole is balanced by others, so their vector sum is zero. Step 5: Conclude that there is no overall molecular dipole moment, meaning CF4 is nonpolar with a symmetric charge distribution.

Verification / Alternative check:
Another way to check is to compare CF4 with molecules of similar geometry. Methane CH4 is also tetrahedral and nonpolar because all bonds and positions are identical. Similarly, CF4 has four identical C F bonds in a symmetric arrangement. In contrast, molecules such as CH3Cl, where one substituent is different, become polar because symmetry is broken. Experimental measurements of dipole moment confirm that CF4 has a dipole moment of essentially zero, supporting the conclusion that it is nonpolar and symmetric in its charge distribution.

Why Other Options Are Wrong:
Option B describes a polar molecule with an asymmetrical distribution of charge. This would apply to molecules like CH3Cl or H2O, not to perfectly symmetric CF4. Option C suggests a nonpolar molecule with an asymmetrical distribution of charge, which is contradictory because an asymmetrical charge distribution usually leads to polarity. Option D describes a polar molecule with symmetrical charge distribution, which is again inconsistent, because true symmetry tends to cancel dipoles and remove net polarity.

Common Pitfalls:
Students often assume that if all bonds are polar, then the whole molecule must be polar. This is not always true. Another common mistake is to think only in two dimensions and overlook the three dimensional tetrahedral structure. Forgetting about molecular geometry can lead to incorrect classification of CF4 as polar. Always combine bond polarity with the molecule three dimensional shape when deciding whether a molecule is polar or nonpolar.

Final Answer:
The correct answer is: A nonpolar molecule with a symmetrical distribution of charge around the central atom.