Atom rotational, vibrational, and translational energy modes have same energy {energy partition} {partition of energy, chemistry}. If energy is different, rotation or vibration gains or loses energy to neighboring rotations and vibrations and returns to equilibrium.
Molecular groups can rotate around single bonds {rotation, bond}. Double bonds, triple bonds, and bonds with resonance have no rotation.
types
Because spherical molecules are symmetric in all three space directions, spherical molecules have no net rotation. Spin around axis leaves molecule the same. Spherical molecules cannot rotate around axis that does not go through center.
Linear molecules can spin around axis perpendicular to chemical bond, so linear molecules can have net rotation. Because linear molecules are symmetric in one space direction, linear molecules have no net rotation around line between nuclei, because spin around that axis leaves molecule the same.
Molecules that are not spherical or linear have no symmetry axis and can rotate around three mutually perpendicular space dimensions.
Molecule bonds can have different vibration types {vibration, molecule}.
types
Vibrations can stretch and compress chemical bonds along line between nuclei. Vibrations can widen and narrow angle between two bonds.
number
Molecules with no bonds cannot vibrate.
Molecules with one bond have one vibration type, bond compressing and stretching.
Molecules with two bonds can have four vibration modes. One bond can stretch, as the other compresses. Both bonds can stretch and compress at same time. Angle between bonds can narrow and widen. One bond can move downward perpendicular to bond plane, while one moves upward perpendicular to bond plane.
symmetry
Molecule symmetries can make two vibration modes indistinguishable and decrease total number of vibration modes.
5-Chemistry-Inorganic-Chemical-Molecule
Outline of Knowledge Database Home Page
Description of Outline of Knowledge Database
Date Modified: 2022.0225