In which of the following molecules/ions is the bond angle largest?

Options

A. `H_(2)O`
B. `SCl_(2)`
C. `IC l_(2)^(-)`
D. `SnCl_(2)`

Answer

To determine which of the given molecules/ions has the largest bond angle, we will analyze the molecular geometry and bond angles of each compound step by step.

### Step 1: Analyze H2O (Water)
- **Central Atom**: Oxygen (O)
- **Valence Electrons**: Oxygen has 6 valence electrons (Group 16).
- **Bond Pairs**: There are 2 hydrogen atoms bonded to oxygen, so there are 2 bond pairs.
- **Lone Pairs**: Oxygen has 4 remaining electrons, which means there are 2 lone pairs.
- **Geometry**: The electron geometry is tetrahedral (due to 4 electron pairs), but the molecular shape is bent due to the 2 lone pairs.
- **Bond Angle**: The ideal tetrahedral angle is 109.5°, but the presence of lone pairs reduces the bond angle to approximately 104.5°.

### Step 2: Analyze SCl2 (Sulfur Dichloride)
- **Central Atom**: Sulfur (S)
- **Valence Electrons**: Sulfur has 6 valence electrons (Group 16).
- **Bond Pairs**: There are 2 chlorine atoms bonded to sulfur, so there are 2 bond pairs.
- **Lone Pairs**: Sulfur has 4 remaining electrons, which means there are 2 lone pairs.
- **Geometry**: The electron geometry is tetrahedral, but the molecular shape is bent due to the 2 lone pairs.
- **Bond Angle**: Similar to H2O, the bond angle is less than 109.5°, approximately around 104.5°.

### Step 3: Analyze ICl2- (Iodine Dichloride Ion)
- **Central Atom**: Iodine (I)
- **Valence Electrons**: Iodine has 7 valence electrons (Group 17).
- **Charge**: The ion has a -1 charge, which adds an extra electron, giving a total of 8 valence electrons.
- **Bond Pairs**: There are 2 chlorine atoms bonded to iodine, so there are 2 bond pairs.
- **Lone Pairs**: Iodine has 6 remaining electrons, which means there are 3 lone pairs.
- **Geometry**: The electron geometry is trigonal bipyramidal (due to 5 electron pairs), but the molecular shape is linear because the 3 lone pairs occupy the equatorial positions.
- **Bond Angle**: The bond angle in a linear shape is 180°.

### Step 4: Analyze SnCl2 (Tin Dichloride)
- **Central Atom**: Tin (Sn)
- **Valence Electrons**: Tin has 4 valence electrons (Group 14).
- **Bond Pairs**: There are 2 chlorine atoms bonded to tin, so there are 2 bond pairs.
- **Lone Pairs**: Tin has 2 remaining electrons, which means there is 1 lone pair.
- **Geometry**: The electron geometry is trigonal planar, but the molecular shape is bent due to the lone pair.
- **Bond Angle**: The ideal bond angle in a trigonal planar structure is 120°, but the presence of the lone pair reduces it to less than 120°.

### Conclusion
After analyzing all the molecules/ions:
- H2O: ~104.5°
- SCl2: ~104.5°
- ICl2-: 180°
- SnCl2: <120°

The molecule/ion with the largest bond angle is **ICL2-**, with a bond angle of **180°**.

### Final Answer
The answer is **ICL2-**.