How many right angle, bond angles are present in `TeF_(5)^(-)` molecular ion ?

Answer

To determine how many right angle bond angles are present in the `TeF_(5)^(-)` molecular ion, we can follow these steps:

### Step 1: Determine the Valence Electrons
Tellerium (Te) is in Group 16 of the periodic table and has 6 valence electrons. Since we are dealing with the `TeF_(5)^(-)` ion, we need to account for the extra electron due to the negative charge. Therefore, the total number of valence electrons is:

\[ 6 \text{ (from Te)} + 5 \times 7 \text{ (from 5 F)} + 1 \text{ (extra electron)} = 6 + 35 + 1 = 42 \text{ electrons} \]

### Step 2: Draw the Lewis Structure
In the Lewis structure, we will place the Te atom in the center and surround it with 5 fluorine (F) atoms. Each F atom forms a single bond with Te, using up 10 electrons (5 bonds). The remaining electrons will be placed as lone pairs on the Te atom.

### Step 3: Identify the Molecular Geometry
With 5 bonding pairs and 1 lone pair, the molecular geometry of `TeF_(5)^(-)` is square pyramidal. The lone pair occupies one of the axial positions, which affects the bond angles.

### Step 4: Determine the Bond Angles
In an ideal square pyramidal structure, the bond angles between the equatorial fluorine atoms would be 90 degrees. However, the presence of the lone pair causes distortion in the bond angles. The ideal bond angle of 90 degrees is compressed due to the lone pair, resulting in bond angles that are less than 90 degrees.

### Step 5: Count the Right Angle Bond Angles
Since the ideal bond angles are distorted due to the lone pair, the actual bond angles between the fluorine atoms will not be 90 degrees. In fact, they are approximately 79 degrees. Therefore, there are no right angle bond angles present in the `TeF_(5)^(-)` molecular ion.

### Final Answer
The number of right angle bond angles in `TeF_(5)^(-)` is **zero**.

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