The vibration of the formaldehyde molecule is composed of six normal modes. Two modes are stretching the molecule along the covalently bound C and H in the σ_v^xz relfection plane. One mode is stretching the molecule along the covalently bound C and O in the σ_v^xz plane, while bending the entire molecule in the same plane. Two other modes are bending the molecule in the σ_v^xz reflection plane, while the remaining mode is bending the molecule out of this plane. The stretching ν₁(A₁) and ν₂(A₁), as well as the deformations ν₃(A₁) and ν₆(B₂) are symmetric with respect to the σ_v^yz reflection plane, while the stretching mode ν₄(B₁) and the deformation ν₆(B₂) are antisymmetric. Formaldehyde is in the C_2v point group with the symmetry elements: C₂ axis (black), σ_v^xz plane (cyan) and σ_v^yz plane (yellow). [compare to water in symotter-gallery]