Question

In white phosphorous \(\left(\mathrm{P}_{4}\right)\) molecule which one is not correct? (a) Six P-P single bonds are present (b) Four P- P simie bondis are mesent (c) Four lone pairs of eleciron are presentid) (d) P P P bond angle is 60

Short answer

Option (b) is not correct.

Step-by-step solution

Read the Question Carefully

We need to determine which statement about the white phosphorus molecule (P_4) is incorrect. The options describe different structural aspects of the molecule.

Understand the Structure of White Phosphorus

White phosphorus (P_4) forms a tetrahedron, where each phosphorus atom is at the vertex of the tetrahedron. Each P atom is connected to three others by a P-P bond, and there are no double bonds in this structure.

Evaluate the Option (a)

Six P-P single bonds are present in one P_4 molecule, as each P atom forms a single bond with the three others. Thus, option (a) is correct.

Evaluate the Option (b)

The option states "Four P-P single bonds are present," which is incorrect because there are six P-P single bonds in P_4. Thus, option (b) is incorrect.

Evaluate the Option (c)

Each phosphorus atom in P_4 has one lone pair of electrons, making a total of four lone pairs (one for each P atom). Option (c) is correct.

Evaluate the Option (d)

The P-P-P bond angle in a tetrahedral P_4 molecule is not 60 degrees; it is approximately 60 degrees due to the tetrahedral shape. Thus, option (d) is an approximation but generally correct in describing the geometry.

Key concepts

Tetrahedral geometry

White phosphorus, represented by the formula \( \mathrm{P}_4 \), has a unique geometric structure known as a tetrahedron. This means that the molecule forms a shape where four phosphorus atoms are placed at the vertices of a tetrahedron. If you imagine a pyramid with a triangular base, the apex and each base corner represent the phosphorus atoms. This configuration is significant because it influences many of the molecule's chemical properties.

• In a tetrahedron, each atom is equidistant from the others.
• The spatial arrangement allows the molecule to be compact and stable.
• The symmetry of the structure is also crucial for understanding how the molecule behaves in different chemical reactions.

Thus, the tetrahedral geometry is essential for visualizing and predicting the behavior of the \( \mathrm{P}_4 \) molecule.

P-P single bonds

Within the \( \mathrm{P}_4 \) molecule, the phosphorus atoms are linked together through what are known as P-P single bonds. Each phosphorus atom forms a single bond with three other phosphorus atoms in this tetrahedral arrangement, resulting in a total of six P-P bonds throughout the molecule.

• Each P-P single bond involves sharing one pair of electrons between two phosphorus atoms.
• The bonding is purely covalent, reflecting the shared nature of electrons within the tetrahedron.
• This bonding pattern allows for a strong, stable structure while maintaining the overall shape of the molecule.

This setup of P-P single bonds is integral to the characteristic properties and reactivity of white phosphorus.

Lone pairs of electrons

Lone pairs refer to pairs of valence electrons that do not participate in bonding. In the case of white phosphorus \( \mathrm{P}_4 \), each of the phosphorus atoms possesses one lone pair of electrons. This observation results from the fact that while three of the valence electrons are used for bonding with adjacent phosphorus atoms, one pair remains non-bonding.

• This lone pair influences both the chemical reactivity and the physical properties of the molecule.
• Lone pairs can affect how a molecule interacts with other substances, often playing a role in its chemical reactions.
• These electron pairs also have a role in the molecule's shape, as they occupy space and can lead to specific interactions or repulsions.

Thus, lone pairs are a critical component in understanding the overall behavior and interaction of white phosphorus.

Molecular bond angles

The bond angles in a molecule are the angles between the lines formed by joining three atoms. For white phosphorus \( \mathrm{P}_4 \), these angles are influenced by the tetrahedral structure. The ideal tetrahedral angle is approximately 109.5 degrees, however, due to the peculiar 3D arrangement and the repulsion involving lone pairs, the actual angles in \( \mathrm{P}_4 \) come closer to 60 degrees.

• The compressed bond angles result from the compact, crowded layout of the atoms in the tetrahedral arrangement.
• This specific angle configuration enhances the molecule's stability but also affects its ability to engage in reactions.
• The understanding of bond angles is pivotal when determining molecular interactions and predicting how the molecule will behave in different chemical environments.

Bond angles are thus crucial to consider when analyzing the geometry and behavior of the \( \mathrm{P}_4 \) molecule.