Problem 129 - A Complete Resource Book in Chemistry for JEE Main

Question

Which statement is wrong bout structure of phosphorus (V) oxide? (a) Each 'P' atom is sp \(^{3}\) hybridized (b) It has \(6 \mathrm{P}-\mathrm{O}-\mathrm{P}\) bonds. (c) IT has POP angle of \(180^{\circ}\). (d) It has two types of \(\mathrm{P}-\mathrm{O}\) bond lengths.\(\begin{array}{llll}\text { (a) } & \text { p } & \text { q } & \text { r } \\ \text { (a) } & \text { O } & \text { O }\end{array}\) (b) \(\mathrm{O} \quad \mathrm{O}\) \(\mathrm{O} \quad \mathrm{O}\) \(\begin{array}{llll}\text { (c) } \mathrm{O} & \mathrm{O} & \mathrm{O} & \mathrm{O}\end{array}\) (d) \(\mathrm{O}\) O \(\mathrm{O} \quad \mathrm{O}\)

Step-by-Step Solution

Answer

Statement (c) is wrong; P-O-P angles are not 180°.

Step 1: Understanding the Structure of Phosphorus (V) Oxide

Phosphorus (V) oxide, also known as P₄O₁₀, consists of P₄ tetrahedra linked through oxygen atoms. Each phosphorus atom is at the center of a tetrahedron and is bonded to four oxygen atoms, leading to an sp³ hybridization. This structure forms a cage-like architecture.

Step 2: Analyzing the Hybridization

Check whether each phosphorus atom in phosphorus (V) oxide is sp³ hybridized. In P₄O₁₀, each phosphorus atom forms four sigma bonds with oxygen atoms, which supports the sp³ hybridization. Thus, statement (a) is correct.

Step 3: Checking for P-O-P Bonds

Count the P-O-P linkages within the structure. In the P₄O₁₀ molecule, there are 6 P-O-P linkages, where oxygen atoms bridge the phosphorus atoms. Therefore, statement (b) regarding the number of P-O-P bonds is true.

Step 4: Examine P-O-P Angle

Evaluate the P-O-P bond angles. In P₄O₁₀, due to the molecular geometry, the P-O-P bond angles are not linear but instead are much less than 180°. This makes statement (c) incorrect.

Step 5: Assessing Types of P-O Bonds

Now, check if there are different types of P-O bond lengths. In P₄O₁₀, there are two distinct types of P-O bonds: terminal P=O bonds and bridging P-O-P bonds, which have different lengths. Hence, statement (d) is true.

Key Concepts

Hybridization in Phosphorus Compounds

In phosphorus compounds like Phosphorus Pentoxide (P₄O₁₀), each phosphorus atom is found at the center of a tetrahedral unit. The key to understanding this structure is recognizing the type of hybridization occurring at each phosphorus atom.
In P₄O₁₀, each phosphorus forms four sigma bonds with oxygen atoms. These bonds occur when orbitals hybridize. In this structure, the hybridization is of the type sp³.

• Sp³ hybridization means that one s-orbital and three p-orbitals combine to form four equivalent hybrid orbitals.
• These hybrid orbitals then arrange themselves in a tetrahedral geometry.
• This tetrahedral shape is common in molecules where atoms are bonded in a way that involves four regions of electron density surrounding the central atom.

This specific hybridization pattern ensures that each phosphorus atom can effectively form a stable structure with oxygen atoms, leading to the interesting cage-like formation in P₄O₁₀.

P-O-P Linkages

In the structure of Phosphorus Pentoxide (P₄O₁₀), a fascinating aspect is the presence of P-O-P links. These are covalent bonds that bridge phosphorus atoms through oxygen atoms. Understanding this aspect gives insights into the compound's stability and overall architecture.

• The molecule has a total of 6 P-O-P linkages.
• Each linkage consists of a single oxygen atom connecting two phosphorus atoms.
• This type of linkage is crucial for maintaining the integrity of the polymer-like structure of P₄O₁₀.
• The bridging oxygens result in a 3D network that forms a sort of molecular cage around the phosphorus centers.

These P-O-P linkages are what help provide structural robustness to the molecule, allowing it to form a stable, cage-like network that is characteristic of Phosphorus Pentoxide.

Bond Angles in Molecules

Bond angles play an essential role in defining the shape and geometry of molecules, including Phosphorus Pentoxide (P₄O₁₀). Within this compound, the P-O-P linkages create specific bond angles that significantly influence the overall 3D structure.

• In P₄O₁₀, contrary to what might be expected, the P-O-P bond angles are not linear (or 180°).
• These angles are constrained by the tetrahedral arrangement around phosphorus atoms, resulting in angles significantly less than 180°.
• This deviation from linear angles is crucial because it supports the cage-like, three-dimensional configuration of the structure.
• Understanding these bond angles is essential to predict the reactivity and interaction of P₄O₁₀ with other molecules.

The angles formed between phosphorus and oxygen in the linkages highlight how geometric constraints influence the physical and chemical properties of molecular structures.