. DEFINE BOND ANGLE
The bond angle is defined as the average angle between the lines representing the orbitals containing the bonding electrons.
Bond angle is expressed in degree/minute/seconds. For example, H—C—H bond angle in CH4 molecule is 109° 28'. Similarly, F—B—F bond angle in BF3 is 120° and H—N—H bond angle in NH3 molecule is 107°.
The bond angles in CH4, NH3, H2O and BF3 molecules are shown below in Figure below.