The chemistry of Be is very similar to that of aluminium, because

Options

A. They belong to same group
B. They belong to same period
C. Both have nearly the same ionic size
D. The ratio of their charge to size is nearly the same

Answer

To determine why the chemistry of beryllium (Be) is very similar to that of aluminum (Al), we can analyze the options provided and understand the underlying concepts.

### Step-by-Step Solution:

1. **Identify the Position of Elements in the Periodic Table**:
- Beryllium (Be) is located in Group 2 and Period 2 of the periodic table.
- Aluminum (Al) is located in Group 13 and Period 3.

2. **Understand the Concept of Diagonal Relationship**:
- Elements in Period 2 and Period 3 can exhibit a diagonal relationship, which means that certain properties of elements in these periods can be similar.
- This relationship occurs due to the similar charge-to-size ratios of these elements.

3. **Analyze the Options**:
- **Option 1**: They belong to the same group. (Incorrect, Be is in Group 2 and Al is in Group 13)
- **Option 2**: They belong to the same period. (Incorrect, Be is in Period 2 and Al is in Period 3)
- **Option 3**: Both have nearly the same ionic size. (Not entirely accurate, as ionic sizes differ)
- **Option 4**: The ratio of their charge to mass is nearly the same. (Correct, as both Be and Al have similar polarizing power due to their charge-to-size ratios)

4. **Conclusion**:
- The chemistry of beryllium is very similar to that of aluminum primarily because they have similar polarizing power, which is a result of their comparable charge-to-size ratios. This is why the correct answer is **Option 4**.

### Final Answer:
The chemistry of Be is very similar to that of Al because the ratio of their charge to size is nearly the same.

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