Final answer:
Hybrid orbitals are formed from the mixing of atomic orbitals on a bonded atom to explain the shapes of molecules as observed in nature, and are a crucial aspect of valence bond theory. Hybridization only occurs in covalently bonded atoms and results in orbitals different in shape and orientation from the atomic orbitals of isolated atoms. For example, sp hybridization involves the mixing of one s and one p orbital to form two new equivalent orbitals.
Step-by-step explanation:
Understanding Hybrid Orbitals
Developing the concept of hybrid orbitals is an essential part of valence bond theory, explaining how atoms bond to form molecules with specific shapes. According to this theory, hybridization occurs when atomic orbitals with similar energy levels on the same atom mix to form new orbitals. These new orbitals are called hybrid orbitals because they arise from the combination (hybridization) of different types of orbitals, such as s and p orbitals.
An atomic orbital, like the s or p orbital, is a region in space where there is a high probability of finding an electron. When we observe molecules with particular shapes, we see that these shapes do not match up with the standard atomic orbitals. To explain the observed molecular geometries, hybrid orbitals are introduced. These orbitals arise only when atoms are bonded to each other, not when atoms are isolated.
For instance, in sp hybridization, a single s orbital combines with one p orbital to create two new equivalent hybrid orbitals. These sp orbitals have a linear arrangement and are 180° apart. In the molecule BeCl₂, the central beryllium atom undergoes sp hybridization to form two identical sigma (σ) bonds with chlorine atoms.
Other common types of hybridization include sp² and sp³, related to trigonal planar and tetrahedral electron-pair geometries, respectively. The VSEPR theory, which predicts the shape of molecules based on electron-pair repulsion, works hand-in-hand with the concept of hybridization to explain molecular structures.