Hybridisation of chromium ions in chromate and dichromate ions is respectively

Options

A. `sp^(2) and sp^(2)`
B. `sp^(2) and sp^(3)`
C. `sp^(3) and sp^(2)`
D. `sp^(3) and sp^(3)`

Answer

To determine the hybridization of chromium ions in chromate (CrO4²⁻) and dichromate (Cr2O7²⁻) ions, we can follow these steps:

### Step 1: Identify the Structure of Chromate Ion (CrO4²⁻)
- The chromate ion consists of one chromium atom surrounded by four oxygen atoms.
- The structure can be represented as:
```
O
||
O - Cr - O
|
O
```
- In this structure, there are four sigma bonds formed between the chromium and the oxygen atoms.

### Step 2: Determine the Hybridization of Chromate Ion
- The hybridization can be determined using the steric number, which is the number of sigma bonds plus the number of lone pairs around the central atom.
- For CrO4²⁻, the steric number is 4 (since there are 4 sigma bonds and no lone pairs).
- A steric number of 4 corresponds to sp³ hybridization.

### Step 3: Identify the Structure of Dichromate Ion (Cr2O7²⁻)
- The dichromate ion consists of two chromium atoms and seven oxygen atoms.
- The structure can be represented as:
```
O
||
O - Cr - O
|
O
|
O - Cr - O
||
O
```
- In this structure, there are a total of 8 sigma bonds (4 from each chromium atom) and 4 pi bonds (due to the double bonds with oxygen).

### Step 4: Determine the Hybridization of Dichromate Ion
- For the dichromate ion, we need to calculate the hybridization for one chromium atom.
- Each chromium atom in the dichromate ion has a steric number of 4 (4 sigma bonds and no lone pairs).
- Thus, the hybridization for each chromium ion in the dichromate ion is also sp³.

### Conclusion
- The hybridization of chromium ions in both chromate and dichromate ions is sp³.

### Final Answer
- The hybridization of chromium ions in chromate and dichromate ions is respectively sp³ and sp³.

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