Which has maximum XCX bond angle ? (X=F,Cl,Br)

Options

A. `CHF_(3)`
B. `CHCl _(3)`
C. `CHBr_(3)`
D. All have similar bond angle

Answer

To determine which compound has the maximum X-C-X bond angle among CHF3, CHCl3, and CHBr3, we can follow these steps:

### Step 1: Understand the Molecular Geometry
All three compounds (CHF3, CHCl3, CHBr3) have a tetrahedral geometry because the central carbon atom is bonded to four atoms (three halogens and one hydrogen). In tetrahedral geometry, the ideal bond angle is approximately 109.5 degrees.

**Hint:** Remember that the geometry of a molecule can influence the bond angles due to the arrangement of electron pairs around the central atom.

### Step 2: Analyze the Size of Halogens
The halogens in question (F, Cl, Br) increase in size as we move down the group in the periodic table. Fluorine is the smallest, followed by chlorine, and bromine is the largest. The larger the atom, the greater the steric repulsion between the bonded atoms.

**Hint:** Consider how the size of the bonded atoms affects the space they occupy and the resulting bond angles.

### Step 3: Consider Electronegativity
Fluorine is the most electronegative element, which means it attracts the shared electrons in the bond more strongly than chlorine or bromine. This can lead to less crowding around the carbon atom when bonded to fluorine, resulting in a smaller bond angle.

**Hint:** Electronegativity can influence the distribution of electron density and thus affect bond angles.

### Step 4: Evaluate Repulsion Effects
In CHBr3, the bromine atoms are larger and have less electronegativity compared to fluorine and chlorine. This means there will be greater electron-electron repulsion between the bromine atoms, which can push the bond angles wider.

**Hint:** Greater repulsion between larger atoms can lead to increased bond angles.

### Step 5: Compare the Bond Angles
- In CHF3, the bond angle is likely to be the smallest due to the high electronegativity of fluorine and less steric repulsion.
- In CHCl3, the bond angle will be slightly larger than in CHF3 but still smaller than in CHBr3.
- In CHBr3, the bond angle will be the largest due to the larger size of bromine and the increased repulsion between the bromine atoms.

### Conclusion
Based on the analysis, the compound with the maximum X-C-X bond angle is CHBr3.

**Final Answer:** CHBr3 has the maximum X-C-X bond angle.