Atomic orbitals are mathematical functions that describe the probability distribution of finding an electron in an atom. The notations sp, sp², and sp³ refer to hybrid orbitals formed by the combination of atomic orbitals.
sp³ Hybridization: In sp³ hybridization, one s orbital and three p orbitals from the same atom combine to form four sp³ hybrid orbitals. These hybrid orbitals are arranged in a tetrahedral geometry around the central atom. The classic example of sp³ hybridization is found in methane (CH₄), where the carbon atom forms four sigma (σ) bonds with four hydrogen atoms.
sp² Hybridization: In sp² hybridization, one s orbital and two p orbitals from the same atom combine to form three sp² hybrid orbitals. These hybrid orbitals lie in the same plane and are arranged in a trigonal planar geometry. Each sp² hybrid orbital can form a sigma (σ) bond with other atoms. An unhybridized p orbital perpendicular to the plane of sp² hybrid orbitals remains unchanged and can participate in pi (π) bonding. An example of sp² hybridization is found in molecules like ethylene (C₂H₄), where the carbon atoms are connected by a double bond.
sp Hybridization: In sp hybridization, one s orbital and one p orbital from the same atom combine to form two sp hybrid orbitals. These hybrid orbitals are linearly oriented at an angle of 180 degrees. Like sp² hybridization, an unhybridized p orbital perpendicular to the plane of sp hybrid orbitals can participate in pi (π) bonding. An example of sp hybridization is found in molecules like acetylene (C₂H₂), where the carbon atoms are connected by a triple bond.
To identify the type of hybridization in a molecule, you can examine the molecular geometry and the number of sigma and pi bonds formed by the central atom. The hybridization is determined by the combination of atomic orbitals necessary to achieve the observed molecular geometry.
It's important to note that the concept of hybridization is a simplified model used to explain molecular geometries and bonding. It does not represent the true behavior of electrons in atoms, but it provides a useful framework to understand molecular structures.