Introduction:
Hybridization refers to the mixing of atomic orbitals to form hybrid orbitals. These hybrid orbitals have different shapes and energies than the original atomic orbitals and are involved in the bonding of atoms in a molecule. Hybridization is commonly observed in molecules containing carbon, such as methane (CH4), where the carbon atom undergoes sp3 hybridization.

Explanation:
Phosphine (PH3) is a molecule composed of one phosphorus atom bonded to three hydrogen atoms. The electron configuration of phosphorus in its ground state is [Ne]3s23p3. In the case of phosphine, the phosphorus atom does not undergo hybridization. There are several reasons for this:

Electronic Configuration:
Phosphine has 5 valence electrons, with three electrons in the 3p orbital and two electrons in the 3s orbital. In the ground state, these electrons occupy separate orbitals. Therefore, there is no need for hybridization to occur as there are enough available orbitals to accommodate the bonding electrons.

Single Bonds:
Phosphine forms single bonds with three hydrogen atoms. These single bonds are formed by the overlap of the 3p orbitals of phosphorus with the 1s orbitals of hydrogen. The 3s orbital of phosphorus remains unhybridized and does not participate in bonding. Since only one type of atomic orbital is involved in bonding, there is no requirement for hybridization.

Polarity of the Molecule:
Phosphine is a pyramidal molecule, with the three hydrogen atoms arranged around the central phosphorus atom. Due to the lone pair of electrons on the phosphorus atom, phosphine has a trigonal pyramidal molecular geometry. This arrangement leads to a polar molecule, with the hydrogen atoms having a partial positive charge and the phosphorus atom having a partial negative charge. The polarity of the molecule is a result of the molecular geometry and the distribution of electrons. Hybridization does not affect the polarity of the molecule and is therefore not necessary.

Conclusion:
In conclusion, phosphine (PH3) does not undergo hybridization because it has enough available orbitals to accommodate the bonding electrons without the need for hybridization. The single bonds formed between phosphorus and hydrogen are achieved through the overlap of the 3p orbitals of phosphorus with the 1s orbitals of hydrogen. The molecular geometry of phosphine is trigonal pyramidal, leading to a polar molecule. Overall, the electronic configuration, type of bonding, and molecular geometry of phosphine do not require hybridization for the formation of the molecule.