Name: Lewis Dot Structures
Uploaded: 2019-07-19
Duration: 4 min 41 s
Description: Lewis dot structures, also called electron-dot structures, describe the chemical bonding between atoms in a molecule. Watch the video to learn more.

Question

Explain the formation of

H_{2}

molecule on the basis of valence bond theory.

Accepted Answer

Let us assume that two hydrogen atoms $(A$ and $B)$ with nuclei $(N_{A}$ and $N_{B})$ and electrons $(e_{A}$ and $e_{B})$ are taken to undergo a reaction to form a hydrogen molecule.
When $A$ and $B$ are at a large distance, there is no interaction between them. As they begin to approach each other, the attractive and repulsive forces start operating.

Attractive force arises between:
(a) The nucleus of one atom and its own electron i.e., $N_{A} - e_{A}$ and $N_{B} - e_{B}$ .
(b) The nucleus of one atom and electron of another atom i.e., $N_{A} - e_{B}$ and $N_{B} - e_{A}$ .
Repulsive force arises between:
(a) Electrons of two atoms i.e., $e_{A} - e_{B}$ .
(b) Nuclei of two atoms i.e., $N_{A} - N_{B}$ .

The force of attraction brings the two atoms together, whereas the force of repulsion tends to push them apart.

The magnitude of the attractive forces is more than that of the repulsive forces. Hence, the two atoms approach each other. As a result, the potential energy decreases. Finally, a state is reached when the attractive forces balance the repulsive forces and the system acquires minimum energy. This leads to the formation of a $H_{2}$ molecule.

At this stage two hydrogen atoms are said to be bonded together to form a stable molecule having the bond length of $74 pm$ . Since the energy gets released when the bond is formed between two hydrogen atoms, the hydrogen molecule is more stable than that of isolated hydrogen atoms.

Explain the formation of $H_{2}$ molecule on the basis of valence bond theory.

Important Questions on Chemical Bonding and Molecular Structure

Learn and Prepare for any exam you want !

Explain the formation of H2 molecule on the basis of valence bond theory.

Important Questions on Chemical Bonding and Molecular Structure

Learn and Prepare for any exam you want !

Explain the formation of $H_{2}$ molecule on the basis of valence bond theory.