Q.Give reasons for the following :

Here are the reasons for the given statements:

(i) Covalent bonds are directional bonds while ionic bonds are non-directional.

Let's break down the reasons for each statement, starting with the fundamental nature of chemical bonds and then applying VSEPR theory for molecular geometries.

(i) Covalent bonds are directional bonds while ionic bonds are non-directional.

1. Nature of Covalent Bonds:

   Covalent bonds are formed by the mutual sharing of electrons between two atoms. This sharing occurs through the overlap of atomic orbitals (like s, p, or hybrid orbitals) of the participating atoms. This orbital overlap is specific and occurs in particular regions of space, leading to a concentrated electron density between the nuclei. Because the orbitals themselves have specific orientations in space (e.g., p-orbitals are dumbbell-shaped along axes, hybrid orbitals point in specific directions), the resulting covalent bonds also have definite directions. The arrangement of these directional bonds around a central atom dictates the molecule's geometry.

2. Nature of Ionic Bonds:

   Ionic bonds are formed by the complete transfer of electrons from one atom to another, creating oppositely charged ions (cations and anions). These ions are held together by strong electrostatic forces of attraction. Electrostatic forces are non-directional; a positively charged ion attracts a negatively charged ion equally from all directions around it. There isn't a specific "bond" pointing from one ion to another in a particular direction. Instead, each ion is surrounded by multiple oppositely charged ions in a crystal lattice, where the attractive forces extend uniformly in all directions.

(ii) Water molecule has bent structure whereas carbon dioxide molecule is linear.

This difference in geometry is explained by the Valence Shell Electron Pair Repulsion (VSEPR) theory.

1. Water Molecule ($\text{H}_2\text{O}$):

   • Central Atom: Oxygen ($\text{O}$).
   • Valence Electrons of O: 6.
   • Bonding Pairs: Oxygen forms two single bonds with two hydrogen atoms, so there are 2 bonding pairs.
   • Lone Pairs: The remaining $6 - (2 \times 1) = 4$ valence electrons form 2 lone pairs on the oxygen atom.
   • Total Electron Domains: $2 \text{ (bonding pairs)} + 2 \text{ (lone pairs)} = 4$ electron domains.
   • Electron Geometry: According to VSEPR theory, 4 electron domains arrange themselves in a tetrahedral geometry to minimize repulsion.
   • Molecular Geometry: The presence of two lone pairs on the oxygen atom significantly influences the molecular geometry. Lone pairs exert greater repulsion than bonding pairs. These stronger repulsions push the two $\text{O-H}$ bonding pairs closer together, reducing the $\text{H-O-H}$ bond angle from the ideal tetrahedral angle of $109.5^\circ$ to approximately $104.5^\circ$. This results in a bent or V-shaped molecular structure.

2. Carbon Dioxide Molecule ($\text{CO}_2$):

   • Central Atom: Carbon ($\text{C}$).
   • Valence Electrons of C: 4.
   • Bonding Pairs: Carbon forms two double bonds with two oxygen atoms ($\text{O=C=O}$). For VSEPR theory, a double bond (or a triple bond) is treated as a single "electron domain" or "super pair" because all electrons in that multiple bond are localized between the same two atoms. So, there are 2 effective bonding domains.
   • Lone Pairs: Carbon uses all its 4 valence electrons in forming the two double bonds, so there are 0 lone pairs on the central carbon atom.
   • Total Electron Domains: $2 \text{ (effective bonding domains)} + 0 \text{ (lone pairs)} = 2$ electron domains.
   • Electron Geometry: With 2 electron domains, VSEPR theory predicts a linear electron geometry. …