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 ion \( H_3O^+ \), we can follow these steps:

### Step 1: Determine the number of valence electrons for oxygen.
Oxygen is in group 16 of the periodic table and has 6 valence electrons.

**Hint:** Remember that the group number for main group elements gives you the number of valence electrons.

### Step 2: Identify the number of non-bonding electrons on oxygen.
In \( H_3O^+ \), the oxygen atom has 2 non-bonding electrons (these are the lone pair electrons).

**Hint:** Non-bonding electrons are those that are not involved in bonding with other atoms.

### Step 3: Count the number of shared (bonding) electrons.
In \( H_3O^+ \), oxygen forms three bonds with hydrogen atoms. Each bond consists of 2 electrons, so the total number of shared electrons is \( 3 \times 2 = 6 \) electrons.

**Hint:** Each bond between oxygen and hydrogen contributes 2 electrons to the shared count.

### Step 4: Apply the formal charge formula.
The formal charge (FC) can be calculated using the formula:
\[ \text{FC} = \text{Valence electrons} - \text{Non-bonding electrons} - \frac{1}{2} \times \text{Shared electrons} \]
Substituting the values we have:
\[ \text{FC} = 6 - 2 - \frac{1}{2} \times 6 \]

### Step 5: Calculate the formal charge.
Now, simplify the expression:
\[ \text{FC} = 6 - 2 - 3 = 1 \]

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

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

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