The formal charge on P on the phosphonium ion `(PH_(4)^(+))` is :

Options

A. `-1`
B. `+5`
C. `0`
D. `+1`

Answer

To calculate the formal charge on phosphorus in the phosphonium ion (PH₄⁺), we can follow these steps:

### Step 1: Determine the Valence Electrons
Phosphorus (P) is in Group 15 of the periodic table, which means it has 5 valence electrons.

### Step 2: Account for the Positive Charge
The phosphonium ion (PH₄⁺) has a positive charge, indicating that phosphorus has lost one electron. Therefore, the effective number of valence electrons for phosphorus in this ion is:
\[ 5 \text{ (original valence electrons)} - 1 \text{ (lost electron)} = 4 \text{ electrons} \]

### Step 3: Identify Lone Pair and Bonded Electrons
In the phosphonium ion, phosphorus forms four single bonds with four hydrogen atoms. Thus:
- **Lone Pair Electrons**: 0 (since all valence electrons are involved in bonding)
- **Bonded Electrons**: Each bond with hydrogen contributes 2 electrons (1 from P and 1 from H). With 4 hydrogen atoms:
\[ \text{Total bonded electrons} = 4 \text{ bonds} \times 2 \text{ electrons/bond} = 8 \text{ electrons} \]

### Step 4: Apply the Formal Charge Formula
The formula for calculating formal charge (FC) is:
\[ \text{FC} = \text{Valence Electrons} - \text{Lone Pair Electrons} - \frac{1}{2} \times \text{Bonded Electrons} \]
Substituting the values we have:
\[ \text{FC} = 4 - 0 - \frac{1}{2} \times 8 \]
\[ \text{FC} = 4 - 0 - 4 \]
\[ \text{FC} = 0 \]

### Step 5: Conclusion
The formal charge on phosphorus in the phosphonium ion (PH₄⁺) is **+1**.

### Final Answer
The formal charge on P in the phosphonium ion (PH₄⁺) is **+1**.

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