Question 1

What orbitals does phosphorus use to form five bonds in PCl5?

Accepted Answer

Phosphorus pentachloride has a trigonal bipyramidal shape with five P–Cl bonds. Phosphorus uses its 3s orbital, three 3p orbitals, and one 3d orbital to form five sp3d hybrid orbitals. These five sp3d hybrid orbitals are directly involved in bonding with the five chlorine atoms.

Question 2

How does sp3d2 hybridization explain the octahedral structure of SF6?

Accepted Answer

Sulfur hexafluoride exhibits sp3d2 hybridization, forming six equivalent hybrid orbitals arranged in an octahedral geometry. The sulfur atom combines its 3s orbital, three 3p orbitals, and two 3d orbitals to create six sp3d2 hybrid orbitals. Each hybrid orbital forms a sulfur–fluorine bond directed toward a corner of the octahedron.

Question 3

Why can't pi bonds rotate around the internuclear axis?

Accepted Answer

Pi bonds form from the side-on overlap of two p orbitals, creating electron density on opposite sides of the internuclear axis. This perpendicular arrangement prevents rotation around the bond axis. Pi bonds only form in double and triple bonds when a sigma bond already exists between two atoms.

Question 4

What is the bonding composition of the double bond in ethene?

Accepted Answer

Ethene contains sp2 hybridized carbons that form one carbon–carbon sigma bond through overlap of sp2 hybrid orbitals. The unhybridized 2p orbitals on each carbon overlap sideways to produce a pi bond. Therefore, the ethene double bond consists of one sigma and one pi bond.

Question 5

How does sp hybridization produce the linear geometry of ethyne?

Accepted Answer

In ethyne, both carbon atoms undergo sp hybridization, producing two sp orbitals and leaving two unhybridized 2p orbitals. One sp orbital forms a carbon–carbon sigma bond, while the other forms a carbon–hydrogen sigma bond. The two perpendicular 2p orbitals overlap sideways to form two pi bonds, creating a triple bond.

Question 6

Which atoms can exhibit sp3d and sp3d2 hybridization?

Accepted Answer

Only atoms with d orbitals in their valence subshells can exhibit sp3d and sp3d2 hybridization. This excludes atoms in the first and second periods. Examples include phosphorus in PCl6−, iodine in interhalogens like IF5, and xenon in XeF4, all of which have accessible d orbitals for bonding.

Question 7

How many sigma and pi bonds form in ethyne?

Accepted Answer

Ethyne contains one sigma bond between the two carbon atoms and one sigma bond between each carbon and hydrogen atom, totaling three sigma bonds. Additionally, two pi bonds form from the sideways overlap of unhybridized 2p orbitals. The triple bond consists of one sigma and two pi bonds between carbons.

تهجين المدارات الذرّية II

sp³d و sp³d² تهجين

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تهجين المدارات الذرّية II

sp3d و sp3d 2 تهجين

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sp³d و sp³d² تهجين