In methane, the carbon atom forms four sigma bonds.

• A. Four sigma bonds
• B. Three sigma bonds
• C. Five sigma bonds
• D. Two sigma bonds

Answer: (A)

In methane, carbon forms four covalent bonds by sharing one electron with each of four hydrogen atoms. Those bonds are all sigma bonds, created by head-on overlap of carbon’s sp3 hybrid orbitals with hydrogen’s 1s orbitals. This uses up carbon’s four valence electrons to achieve a full octet, and there are no leftover electrons to make pi bonds, since all bonds are single bonds. The arrangement is tetrahedral, with bond angles about 109.5 degrees, reflecting the four equivalent sp3 hybrids. So there are four sigma bonds around the carbon in CH4.