Formation of Sigma Bond in H₂
The H₂ molecule is formed through a sigma (σ) bond created by the head-on overlap of two hydrogen 1s orbitals. This is a classic example of a covalent bond formed by the sharing of electrons between two atoms.
1. S-S Overlap: The formation of the H₂ molecule involves the overlap of two spherical 1s orbitals along the internuclear axis, resulting in a sigma (σ) bond.
2. Electron Density: When the bond forms, electron density concentrates in the region between the two nuclei, creating a region of high electron probability.
3. Bond Energy: The bond dissociation energy of H₂ is approximately 436 kJ/mol, making it a relatively strong single covalent bond.
4. Bond Length: The internuclear distance in H₂ is about 74 pm (0.74 Å), representing the optimum distance where attractive and repulsive forces are balanced.
5. Molecular Orbital Theory: In MO theory, the formation of H₂ is described by the linear combination of atomic orbitals, resulting in bonding (lower energy) and antibonding (higher energy) molecular orbitals.
6. Symmetry: The H₂ molecule has cylindrical symmetry around the internuclear axis, with the electron density distributed symmetrically.
7. Quantum States: The H₂ molecule can exist in different rotational and vibrational energy states, which can be observed in spectroscopic studies.
8. Bond Order: H₂ has a bond order of 1, indicating a single bond between the two hydrogen atoms.
9. Electron Configuration: The electronic configuration of H₂ can be written as (σ1s)², indicating that the bonding molecular orbital is filled with two electrons.
10. Importance: H₂ is the simplest stable molecule and serves as a fundamental model for understanding chemical bonding in more complex systems.