The molecule CH₂ (methylene) is considered nonpolar. Here’s why:
1. Molecular Geometry:
CH₂ is linear or planar depending on its bonding context (e.g., in CH₂ as part of larger compounds like formaldehyde, H₂C=O). In isolation, CH₂ is planar due to sp² hybridization.
2. Electronegativity:
Carbon and hydrogen have similar electronegativities (2.55 for carbon and 2.20 for hydrogen on the Pauling scale).
The bond between C-H has a slight polarity, but the small difference in electronegativity results in nearly equal charge distribution.
3. Symmetry:
In a molecule like CH₂, the bond dipoles from the two C-H bonds typically cancel out, leading to a nonpolar molecule.
If CH₂ is part of a more complex structure (like CH₂=CH₂, ethylene), its polarity depends on the overall molecular structure. For an isolated CH₂ group, it is considered nonpolar.