Question

What are the points of differences between stretching vibration and bending vibrations?

Answer 1

Hint : The absorption of IR radiation makes the bonds stretch and bend. Stretches correspond to the increasing and decreasing of bond length of a given atom. Radiation in the infrared region within the spectrum has the energy to excite vibrations of valence bonds.

Complete Step By Step Answer:
The periodic motion of the particles and vibration of a medium, commonly result in stretching rotation when almost any physical system is relocated from its equilibrium condition and allowed to respond to the forces which tend to restore equilibrium.
Vibrations are subdivided depending on whether the bond length or angle is changing: They are Stretching and Bending.
$1.$A stretching vibration is the change in bond length. These are of two type.
$(1.1)$ In symmetric stretching, two or more bonds which vibrate in and out together.
$(1.2)$In asymmetrical stretching, the orientation is such that some bonds are getting shorter at the same time as others are getting longer.
$2.$Bending vibration which changes the angle between two bonds.
There are of the following type:
$2.1$Scissoring is the movement of two atoms.
$2.2$Rocking is like the motion of a pendulum on a clock.
$2.3$Wagging is like the motion in which one makes a v sign with your fingers and bend back and forth.
$2.4$Twisting is a motion as if the atoms were walking on a treadmill.

Note :
Normal modes of vibration may be described using displacement coordinates or internal coordinates. for every normal mode of vibration all the coordinates vary periodically with the same frequency and go through equilibrium simultaneously.