Covalent nature of a compound increases with

Options

A. Decrease in cation size
B. Increase in cation size
C. Decrease in anion size
D. Decrease in both cation and anion size

Answer

To determine how the covalent nature of a compound increases, we can analyze the relationship between the sizes of cations and anions, as well as their charges. Here’s a step-by-step solution:

### Step 1: Understand Covalent Character
Covalent character in a compound refers to the extent to which the bond between two atoms exhibits characteristics of covalent bonding, as opposed to ionic bonding. The more covalent character a bond has, the more it resembles a covalent bond.

**Hint:** Remember that covalent bonds involve sharing electrons, while ionic bonds involve the transfer of electrons.

### Step 2: Analyze Cation Size
According to the phasor rule, a smaller cation size increases covalent character. This is because a smaller cation has a higher charge density, meaning it can exert a stronger attractive force on the electrons of the anion.

**Hint:** Think about how a small, highly charged cation can pull electrons closer, leading to more sharing and thus more covalent character.

### Step 3: Analyze Anion Size
In contrast, a larger anion size also increases covalent character. A large anion has its outer electrons farther from the nucleus, which makes them less tightly bound. This allows the cation to polarize the anion more effectively.

**Hint:** Consider how the distance of the outer electrons from the nucleus affects their interaction with the cation.

### Step 4: Charge Consideration
The charge of the cation also plays a crucial role. A higher positive charge on the cation increases its ability to polarize the anion, enhancing covalent character.

**Hint:** Recall that higher charge density leads to stronger electrostatic interactions.

### Step 5: Conclusion
From the analysis, we conclude that the covalent nature of a compound increases with a decrease in cation size and an increase in anion size. This is due to the increased polarization of the anion by the cation, which is more effective when the cation is small and the anion is large.

**Final Answer:** Covalent nature of a compound increases with a decrease in cation size and an increase in anion size.