In a molecule of methane (CH_4), what is the approximate value of the bond angles between the hydrogen atoms (labeled 1)?

• A. 120^ext{o}
• B. 104.5^ext{o}
• C. 90^ext{o}
• D. 109.5^ext{o}

Answer: (D)

Verified step by step guidance

1. Recognize that methane (CH_4) has a central carbon atom bonded to four hydrogen atoms, forming a molecular geometry that minimizes electron pair repulsion.
2. Recall that the electron pairs around the central atom in methane arrange themselves in a tetrahedral geometry to be as far apart as possible.
3. Understand that in a perfect tetrahedral geometry, the bond angles between the hydrogen atoms are all equal.
4. Use the known bond angle for a tetrahedral molecule, which is approximately \$109.5^\circ$.
5. Conclude that the bond angles between the hydrogen atoms in methane are approximately \$109.5^\circ$, not 120°, 104.5°, or 90°.