H2 have higher bond energy than cl2, it is because it depends on the number of electrons because of high electron density between F-F bond it is easily breaks down

The bond energy of H2 is greater than that of Cl2 due to the following reasons:

1. Bond Length:
- The bond length of H2 is shorter than that of Cl2.
- The hydrogen molecule consists of two hydrogen atoms bonded together, while the chlorine molecule consists of two chlorine atoms bonded together.
- The smaller size of hydrogen atoms leads to a shorter bond length, resulting in stronger bonds between the hydrogen atoms.

2. Atomic Size:
- The size of hydrogen atoms is significantly smaller than that of chlorine atoms.
- The smaller size of hydrogen atoms allows for a closer proximity between the two atoms in the H2 molecule.
- This closer proximity results in stronger attractive forces between the atoms, leading to a higher bond energy.

3. Electronegativity:
- Electronegativity is the ability of an atom to attract electrons towards itself in a chemical bond.
- Chlorine is more electronegative than hydrogen.
- The higher electronegativity of chlorine atoms in the Cl2 molecule leads to stronger electron-electron repulsion between the atoms.
- This repulsion weakens the bond between the chlorine atoms and reduces the bond energy.

4. Bond Strength:
- The strength of a covalent bond is determined by the overlap of atomic orbitals and the number of shared electrons.
- The strength of the bond in a hydrogen molecule is greater than that of a chlorine molecule.
- Hydrogen has only one valence electron, so the overlap of atomic orbitals is more effective in forming a strong covalent bond.
- Chlorine, on the other hand, has seven valence electrons and requires one additional electron to complete its octet.
- The additional electron in chlorine atoms reduces the effectiveness of orbital overlap, resulting in a weaker bond and lower bond energy.

Conclusion:
- The bond energy of H2 is greater than that of Cl2 due to factors such as shorter bond length, smaller atomic size, lower electronegativity, and stronger bond strength.
- The combination of these factors leads to a stronger bond between the hydrogen atoms compared to the bond between the chlorine atoms.