Li does not resemble with other alkali metals in following properties?

Options

A. `Li_(2)CO_(3)` decomposes into oxides while other alkali metal carbonate are thermally stable
B. `LICl` is predominately covalent
C. `Li_(3)N` is formed when Li metal is heated with `N_(2)`gas
D. All of these

Answer

To answer the question "Li does not resemble with other alkali metals in the following properties," we will analyze the properties of lithium compared to other alkali metals (sodium, potassium, rubidium, and cesium) and identify the differences.

### Step-by-Step Solution:

1. **Thermal Stability of Carbonates**:
- **Observation**: Lithium carbonate (Li2CO3) decomposes upon heating to form lithium oxide (Li2O) and carbon dioxide (CO2). In contrast, the carbonates of other alkali metals (e.g., Na2CO3, K2CO3) are thermally stable and do not decompose easily.
- **Reason**: The thermal stability of carbonates is influenced by the polarizing power of the cation. Lithium has a higher charge density due to its small size, leading to greater polarizing power, which distorts the carbonate ion and causes decomposition.

2. **Covalent Character of Lithium Compounds**:
- **Observation**: Lithium chloride (LiCl) exhibits predominantly covalent character, while other alkali metal chlorides (e.g., NaCl, KCl) are primarily ionic.
- **Reason**: According to Fajans' rules, the covalent character increases with the charge density of the cation and the size of the anion. Lithium's small size and high charge density lead to significant covalent character in its compounds.

3. **Formation of Nitride**:
- **Observation**: Lithium reacts with nitrogen gas (N2) to form lithium nitride (Li3N), while other alkali metals typically form hydroxides when reacting with nitrogen.
- **Reason**: The unique properties of lithium allow it to form a nitride, which is not the case for other alkali metals due to their larger atomic sizes and lower charge densities.

4. **Conclusion**:
- Based on the observations and reasoning above, lithium does not resemble other alkali metals in the properties discussed. Therefore, the answer to the question is that all the statements regarding lithium's unique properties are correct.

### Final Answer:
Lithium (Li) does not resemble other alkali metals in the following properties:
1. Lithium carbonate decomposes into oxides upon heating, unlike other alkali metal carbonates.
2. Lithium chloride is predominantly covalent, while other alkali metal chlorides are ionic.
3. Lithium forms lithium nitride (Li3N) when heated with nitrogen gas, unlike other alkali metals.

Thus, the correct option is that all of these statements are true regarding lithium's unique properties.

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