Question

What is vsepr theory how does it explain bond angles observed in Ch4 NH3 an H2o

Answer 1

Answer:

In Valence Shell Electron Pair Repulsion (VSEPR) theory, pairs of electrons that surround the central atom of a molecule or ion are arranged as far apart as possible to minimise electron-electron repulsion. Decide which is the central atom in a molecule. ..

Explanation:

In CH4, the central atom is C, which is in sp3 hybridization state. The four H-atoms are situated at the four corners of the tetrahedron. The bond angle between H—C—H is 109.5°, which is called the tetrahedral angle. But in the case of NH3 and H2O molecules, their central atoms N and O have a lone pair of electrons.

Answer 2

In order to identify arrangement of electron pairs around central atom for determination of the shape of molecule and the angles we use the VSEPR theory.

Bond angles observed in CH4, NH3 and H2O are :-

• CH4 :- Methane has got a tetrahedron structure. The four electrons of Carbon pair up with four electrons of Hydrogen at an equal length . There's no distortion in the structure so, the bond angle between each of them is 109.5 degree.
• NH3 :- Ammonia has got a trigonal pyramidal structure. In ammonia there's a lone pair of electron because it doesn't participate in bonding. Because of the lone pair, there is a distortion in structure. So, bond angle of NH3 is 107 degree.
• H20 :- Water molecule has a bent structure. In water molecule there are two lone pair of electrons. Because of the two lone pairs there's a strong repulsion which leads to distortion in shape of the molecule. So, bond angle of H20 is 104.5 degree.