To determine the incorrect trend regarding group 16 hydrides (H₂E), we need to analyze the properties of these hydrides, which include H₂O (water), H₂S (hydrogen sulfide), H₂Se (hydrogen selenide), and H₂Te (hydrogen telluride). Let's evaluate the trends step by step.
### Step 1: Identify the Hydrides
The hydrides of group 16 elements are:
- H₂O (water)
- H₂S (hydrogen sulfide)
- H₂Se (hydrogen selenide)
- H₂Te (hydrogen telluride)
### Step 2: Analyze Bond Angles
- **Trend**: As we move down the group from H₂O to H₂Te, the bond angle decreases.
- **Reason**: The bond angle in H₂O is about 104.5° due to the presence of two lone pairs on oxygen, which cause significant repulsion. In H₂S, H₂Se, and H₂Te, the central atom's size increases, leading to less lone pair-bond pair repulsion, thus decreasing the bond angle.
### Step 3: Analyze Acidity
- **Trend**: The acidic character of the hydrides increases down the group.
- **Reason**: As we move down the group, the electronegativity of the central atom decreases, making it easier to release H⁺ ions. Therefore, H₂S, H₂Se, and H₂Te are more acidic than H₂O.
### Step 4: Analyze Reducing Properties
- **Trend**: All hydrides except H₂O possess reducing properties.
- **Reason**: The metallic character increases down the group, which enhances the tendency of these hydrides to donate electrons. H₂O does not have reducing properties due to its high electronegativity.
### Step 5: Analyze Thermal Stability
- **Trend**: The thermal stability of hydrides decreases down the group.
- **Reason**: As the bond length increases (due to larger atomic size), the bonds become weaker and easier to break, leading to decreased thermal stability.
### Conclusion
From the analysis, we can summarize the trends:
1. Bond angle decreases down the group (incorrect statement).
2. Acidic character increases down the group (correct statement).
3. Reducing properties increase down the group (correct statement).
4. Thermal stability decreases down the group (correct statement).
Thus, the incorrect trend regarding group 16 hydrides is that the bond angle increases down the group.
### Final Answer
The incorrect trend regarding group 16 hydrides (H₂E) is that the bond angle increases down the group.
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