Increasing order of stability of the +2 oxidation of the ions?

Options

A. `Ca^(2+)ltBa^(2+)ltSr^(2+)`
B. `Pb^(2+)ltGe^(2+)ltSn^(2+)`
C. `Ge^(2+)ltSn^(2+)ltPb^(2+)`
D. `Cu^(2+_,tAu^(2+)ltAg^(2+)`

Answer

To determine the increasing order of stability of the +2 oxidation state of the ions, we will analyze the stability of the +2 oxidation state for the elements mentioned: beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), germanium (Ge), tin (Sn), lead (Pb), copper (Cu), silver (Ag), and gold (Au).

### Step-by-Step Solution:

1. **Understanding Oxidation States**: The +2 oxidation state refers to the loss of two electrons. For main group elements, this typically involves the loss of the outermost s and p electrons.

2. **Group Analysis**:
- **Group 2 Elements**: Beryllium (Be), Magnesium (Mg), Calcium (Ca), Strontium (Sr), Barium (Ba)
- As we move down the group from Be to Ba, the stability of the +2 oxidation state increases due to the larger atomic size and lower ionization energy. However, the inert pair effect becomes significant for heavier elements, leading to decreased stability.
- **Group 14 Elements**: Carbon (C), Silicon (Si), Germanium (Ge), Tin (Sn), Lead (Pb)
- Similar to Group 2, as we move down the group, the stability of the +2 oxidation state generally increases, but the inert pair effect also plays a role, particularly for Sn and Pb.
- **Transition Metals**: Copper (Cu), Silver (Ag), Gold (Au)
- The +2 oxidation state is stable for these metals, but the stability can vary due to d-orbital involvement and the inert pair effect.

3. **Inert Pair Effect**: The inert pair effect refers to the tendency of the s-electrons to remain non-bonding in heavier elements. This effect becomes more pronounced down the group, leading to a decrease in the stability of higher oxidation states.

4. **Stability Order**:
- For the alkaline earth metals (Group 2): The order of stability is Be < Mg < Ca < Sr < Ba.
- For Group 14 elements: The order is C < Si < Ge < Sn < Pb.
- For transition metals: The order is Cu < Ag < Au.

5. **Combining the Results**:
- Considering the inert pair effect and the general trends in stability, we can combine the results to find the overall increasing order of stability of the +2 oxidation states:
- Be < Mg < Ca < Sr < Ba < C < Si < Ge < Sn < Pb < Cu < Ag < Au.

### Final Increasing Order of Stability of +2 Oxidation States:
**Be < Mg < Ca < Sr < Ba < C < Si < Ge < Sn < Pb < Cu < Ag < Au**