Q. \( \text{ch4} \ \) molecular polarity.

Goal: Determine whether a molecule is polar or nonpolar based on its bonding and molecular shape, and explain how to decide for CH₄ (methane).

Step 1: Identify the molecule and its geometry

Methane is CH₄. It has one carbon atom in the center and four hydrogen atoms attached to it.

To predict molecular shape, use the idea of electron domains (VSEPR concept):

• The carbon atom is bonded to 4 hydrogen atoms.
• That gives 4 bonding regions around carbon.
• With 4 electron domains, the geometry is tetrahedral.

So the molecular shape is tetrahedral, with bond angles close to \(109.5^\circ\).

Step 2: Determine whether each C–H bond is polar

Polarity of a bond comes from differences in electronegativity.

• Carbon (C) is slightly more electronegative than hydrogen (H).
• Therefore, each C–H bond has a small bond dipole moment pointing toward carbon.

So: each individual C–H bond is polar.

Step 3: Check whether the bond dipoles cancel

The overall molecular polarity depends on whether the vector sum of all bond dipoles is zero.

In CH₄, the four C–H bond dipoles are arranged symmetrically in a tetrahedral shape.

Because the geometry is perfectly symmetric:

• The dipole moments have equal magnitude (all C–H bonds are identical).
• The dipoles point in directions that are evenly distributed around the center.

These equal and opposite components cancel out.

As a result, the net dipole moment of the molecule is \(0\).

Step 4: Conclude the molecular polarity

Even though each C–H bond is polar, the tetrahedral symmetry causes cancellation of dipoles.

Therefore, methane (CH₄) is nonpolar overall.

Final Answer: CH₄ is molecularly nonpolar because it is tetrahedral and the polar C–H bond dipoles cancel, giving a net dipole moment of \(0\).