In `H_(3)O^(+)` the formal charge on the oxygen atom is :

Options

A. `+1`
B. `-1`
C. zero
D. `+2`

Explanation

To find the formal charge on the oxygen atom in the hydronium ion \( H_3O^+ \), we can follow these steps:

### Step 1: Determine the Valence Electrons for Oxygen
Oxygen is in group 16 of the periodic table, which means it has 6 valence electrons.

**Hint:** Remember that the group number of an element can help determine the number of valence electrons it has.

### Step 2: Count the Non-bonded Electrons
In the hydronium ion \( H_3O^+ \), the oxygen atom has one lone pair of electrons. Each lone pair consists of 2 electrons.

**Hint:** A lone pair is a pair of valence electrons that are not involved in bonding.

### Step 3: Count the Bonded Electrons
Oxygen in \( H_3O^+ \) forms three bonds with three hydrogen atoms. Each bond consists of 2 electrons, so for three bonds, the total number of bonded electrons is \( 3 \times 2 = 6 \) electrons.

**Hint:** Each bond between two atoms involves a shared pair of electrons.

### Step 4: Apply the Formal Charge Formula
The formal charge (FC) can be calculated using the formula:
\[ \text{FC} = \text{(Valence Electrons)} - \text{(Non-bonded Electrons)} - \frac{1}{2} \times \text{(Bonded Electrons)} \]

Substituting the values we have:
- Valence Electrons = 6
- Non-bonded Electrons = 2 (from the lone pair)
- Bonded Electrons = 6

Now, plug these into the formula:
\[ \text{FC} = 6 - 2 - \frac{1}{2} \times 6 \]
\[ \text{FC} = 6 - 2 - 3 = 1 \]

### Step 5: Conclusion
The formal charge on the oxygen atom in \( H_3O^+ \) is +1.

**Final Answer:** The formal charge on the oxygen atom in \( H_3O^+ \) is +1.

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